Movatterモバイル変換

function(){

"use strict";return (function f(n){ if (n <= 0) { return "foo"; } return f(n - 1);}(1e6)) === "foo";

}

function(){

"use strict";return (function f(n){ if (n <= 0) { return "foo"; } return f(n - 1);}(1e6)) === "foo";

}

function(){

"use strict";function f(n){ if (n <= 0) { return "foo"; } return g(n - 1);}function g(n){ if (n <= 0) { return "bar"; } return f(n - 1);}return f(1e6) === "foo" && f(1e6+1) === "bar";

}

function(){

"use strict";function f(n){ if (n <= 0) { return "foo"; } return g(n - 1);}function g(n){ if (n <= 0) { return "bar"; } return f(n - 1);}return f(1e6) === "foo" && f(1e6+1) === "bar";

}

function(){

return (function (a = 1, b = 2) { return a === 3 && b === 2; }(3));

}

function(){

return (function (a = 1, b = 2) { return a === 3 && b === 2; }(3));

}

function(){

return (function (a = 1, b = 2) { return a === 1 && b === 3; }(undefined, 3));

}

function(){

return (function (a = 1, b = 2) { return a === 1 && b === 3; }(undefined, 3));

}

function(){

return (function (a, b = a) { return b === 5; }(5));

}

function(){

return (function (a, b = a) { return b === 5; }(5));

}

function(){

return (function (a = "baz", b = "qux", c = "quux") { a = "corge"; // The arguments object is not mapped to the // parameters, even outside of strict mode. return arguments.length === 2 && arguments[0] === "foo" && arguments[1] === "bar";}("foo", "bar"));

}

function(){

}

function(){

return (function(x = 1) { try { eval("(function(a=a){}())"); return false; } catch(e) {} try { eval("(function(a=b,b){}())"); return false; } catch(e) {} return true;}());

}

function(){

return (function(x = 1) { try { eval("(function(a=a){}())"); return false; } catch(e) {} try { eval("(function(a=b,b){}())"); return false; } catch(e) {} return true;}());

}

function(){

return (function(a=function(){ return typeof b === 'undefined';}){ var b = 1; return a();}());

}

function(){

return (function(a=function(){ return typeof b === 'undefined';}){ var b = 1; return a();}());

}

function(){

return new Function("a = 1", "b = 2", "return a === 3 && b === 2;")(3);

}

function(){

return new Function("a = 1", "b = 2", "return a === 3 && b === 2;")(3);

}

function(){

return (function (foo, ...args) { return args instanceof Array && args + "" === "bar,baz";}("foo", "bar", "baz"));

}

function(){

return (function (foo, ...args) { return args instanceof Array && args + "" === "bar,baz";}("foo", "bar", "baz"));

}

function(){

return function(a, ...b){}.length === 1 && function(...c){}.length === 0;

}

function(){

return function(a, ...b){}.length === 1 && function(...c){}.length === 0;

}

function(){

return (function (foo, ...args) { foo = "qux"; // The arguments object is not mapped to the // parameters, even outside of strict mode. return arguments.length === 3 && arguments[0] === "foo" && arguments[1] === "bar" && arguments[2] === "baz";}("foo", "bar", "baz"));

}

function(){

}

function(){

return (function (...args) { try { eval("({set e(...args){}})"); } catch(e) { return true; }}());

}

function(){

return (function (...args) { try { eval("({set e(...args){}})"); } catch(e) { return true; }}());

}

function(){

return new Function("a", "...b", "return b instanceof Array && a+b === 'foobar,baz';")('foo','bar','baz');

}

function(){

return new Function("a", "...b", "return b instanceof Array && a+b === 'foobar,baz';")('foo','bar','baz');

}

function(){

return Math.max(...[1, 2, 3]) === 3

}

function(){

return Math.max(...[1, 2, 3]) === 3

}

function(){

return [...[1, 2, 3]][2] === 3;

}

function(){

return [...[1, 2, 3]][2] === 3;

}

function(){

var a = Array(...[,,]);return "0" in a && "1" in a && '' + a[0] + a[1] === "undefinedundefined";

}

function(){

var a = Array(...[,,]);return "0" in a && "1" in a && '' + a[0] + a[1] === "undefinedundefined";

}

function(){

var a = [...[,,]];return "0" in a && "1" in a && '' + a[0] + a[1] === "undefinedundefined";

}

function(){

var a = [...[,,]];return "0" in a && "1" in a && '' + a[0] + a[1] === "undefinedundefined";

}

function(){

return Math.max(..."1234") === 4;

}

function(){

return Math.max(..."1234") === 4;

}

function(){

return ["a", ..."bcd", "e"][3] === "d";

}

function(){

return ["a", ..."bcd", "e"][3] === "d";

}

function(){

return Array(..."𠮷𠮶")[0] === "𠮷";

}

function(){

return Array(..."𠮷𠮶")[0] === "𠮷";

}

function(){

return [..."𠮷𠮶"][0] === "𠮷";

}

function(){

return [..."𠮷𠮶"][0] === "𠮷";

}

function(){

var iterable = (function*(){ yield 1; yield 2; yield 3; }());return Math.max(...iterable) === 3;

}

function(){

var iterable = (function*(){ yield 1; yield 2; yield 3; }());return Math.max(...iterable) === 3;

}

function(){

var iterable = (function*(){ yield "b"; yield "c"; yield "d"; }());return ["a", ...iterable, "e"][3] === "d";

}

function(){

var iterable = (function*(){ yield "b"; yield "c"; yield "d"; }());return ["a", ...iterable, "e"][3] === "d";

}

function(){

var iterable = global.__createIterableObject([1, 2, 3]);return Math.max(...iterable) === 3;

}

function(){

var iterable = global.__createIterableObject([1, 2, 3]);return Math.max(...iterable) === 3;

}

function(){

var iterable = global.__createIterableObject(["b", "c", "d"]);return ["a", ...iterable, "e"][3] === "d";

}

function(){

var iterable = global.__createIterableObject(["b", "c", "d"]);return ["a", ...iterable, "e"][3] === "d";

}

function(){

var iterable = global.__createIterableObject([1, 2, 3]);return Math.max(...Object.create(iterable)) === 3;

}

function(){

var iterable = global.__createIterableObject([1, 2, 3]);return Math.max(...Object.create(iterable)) === 3;

}

function(){

var iterable = global.__createIterableObject(["b", "c", "d"]);return ["a", ...Object.create(iterable), "e"][3] === "d";

}

function(){

var iterable = global.__createIterableObject(["b", "c", "d"]);return ["a", ...Object.create(iterable), "e"][3] === "d";

}

function(){

try { Math.max(...2);} catch(e) { return Math.max(...[1, 2, 3]) === 3;}

}

function(){

try { Math.max(...2);} catch(e) { return Math.max(...[1, 2, 3]) === 3;}

}

function(){

var x = 'y';return ({ [x]: 1 }).y === 1;

}

function(){

var x = 'y';return ({ [x]: 1 }).y === 1;

}

function(){

var a = 7, b = 8, c = {a,b};return c.a === 7 && c.b === 8;

}

function(){

var a = 7, b = 8, c = {a,b};return c.a === 7 && c.b === 8;

}

function(){

return ({ y() { return 2; } }).y() === 2;

}

function(){

return ({ y() { return 2; } }).y() === 2;

}

function(){

return ({ "foo bar"() { return 4; } })["foo bar"]() === 4;

}

function(){

return ({ "foo bar"() { return 4; } })["foo bar"]() === 4;

}

function(){

var x = 'y';return ({ [x](){ return 1 } }).y() === 1;

}

function(){

var x = 'y';return ({ [x](){ return 1 } }).y() === 1;

}

function(){

var x = 'y', valueSet, obj = { get [x] () { return 1 }, set [x] (value) { valueSet = value } };obj.y = 'foo';return obj.y === 1 && valueSet === 'foo';

}

function(){

var x = 'y', valueSet, obj = { get [x] () { return 1 }, set [x] (value) { valueSet = value } };obj.y = 'foo';return obj.y === 1 && valueSet === 'foo';

}

function(){

var arr = [5];for (var item of arr) return item === 5;

}

function(){

var arr = [5];for (var item of arr) return item === 5;

}

function(){

var arr = [,,];var count = 0;for (var item of arr) count += (item === void undefined);return count === 2;

}

function(){

var arr = [,,];var count = 0;for (var item of arr) count += (item === void undefined);return count === 2;

}

function(){

var str = "";for (var item of "foo") str += item;return str === "foo";

}

function(){

var str = "";for (var item of "foo") str += item;return str === "foo";

}

function(){

var str = "";for (var item of "𠮷𠮶") str += item + " ";return str === "𠮷𠮶 ";

}

function(){

var str = "";for (var item of "𠮷𠮶") str += item + " ";return str === "𠮷𠮶 ";

}

function(){

var result = "";var iterable = (function*(){ yield 1; yield 2; yield 3; }());for (var item of iterable) { result += item;}return result === "123";

}

function(){

var result = "";var iterable = (function*(){ yield 1; yield 2; yield 3; }());for (var item of iterable) { result += item;}return result === "123";

}

function(){

var result = "";var iterable = global.__createIterableObject([1, 2, 3]);for (var item of iterable) { result += item;}return result === "123";

}

function(){

var result = "";var iterable = global.__createIterableObject([1, 2, 3]);for (var item of iterable) { result += item;}return result === "123";

}

function(){

var result = "";var iterable = global.__createIterableObject([1, 2, 3]);for (var item of Object.create(iterable)) { result += item;}return result === "123";

}

function(){

var result = "";var iterable = global.__createIterableObject([1, 2, 3]);for (var item of Object.create(iterable)) { result += item;}return result === "123";

}

function(){

var closed = false;var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});for (var it of iter) break;return closed;

}

function(){

var closed = false;var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});for (var it of iter) break;return closed;

}

function(){

var closed = false;var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});try { for (var it of iter) throw 0;} catch(e){}return closed;

}

function(){

var closed = false;var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});try { for (var it of iter) throw 0;} catch(e){}return closed;

}

function(){

return 0o10 === 8 && 0O10 === 8;

}

function(){

return 0o10 === 8 && 0O10 === 8;

}

function(){

return 0b10 === 2 && 0B10 === 2;

}

function(){

return 0b10 === 2 && 0B10 === 2;

}

function(){

return Number('0o1') === 1;

}

function(){

return Number('0o1') === 1;

}

function(){

return Number('0b1') === 1;

}

function(){

return Number('0b1') === 1;

}

function(){

var a = "ba", b = "QUX";return `foo bar${a + "z"} ${b.toLowerCase()}` === "foo bar\nbaz qux";

}

function(){

var a = "ba", b = "QUX";return `foo bar${a + "z"} ${b.toLowerCase()}` === "foo bar\nbaz qux";

}

function(){

var a = { toString: function() { return "foo"; }, valueOf: function() { return "bar"; }};return `${a}` === "foo";

}

function(){

var a = { toString: function() { return "foo"; }, valueOf: function() { return "bar"; }};return `${a}` === "foo";

}

function(){

}

function(){

}

function(){

return (function(parts) { return Object.isFrozen(parts) && Object.isFrozen(parts.raw);}) `foo${0}bar${0}baz`;

}

function(){

return (function(parts) { return Object.isFrozen(parts) && Object.isFrozen(parts.raw);}) `foo${0}bar${0}baz`;

}

function(){

var cr = eval("`x" + String.fromCharCode(13) + "y`");var lf = eval("`x" + String.fromCharCode(10) + "y`");var crlf = eval("`x" + String.fromCharCode(13,10) + "y`");return cr.length === 3 && lf.length === 3 && crlf.length === 3 && cr[1] === lf[1] && lf[1] === crlf[1] && crlf[1] === '\n';

}

function(){

}

function(){

// TemplateStrings caching was changed from per-contents to// per-call-site.// https://github.com/tc39/ecma262/pull/890function strings(array) { return array;}function getStrings() { return strings`foo`;}var original = getStrings();var other = strings`foo`;return original === getStrings() && original !== other;

}

function(){

}

function(){

function strings(array) { return array;}function getStrings() { return strings`foo`;}var original = getStrings();var newed = new getStrings();return original === getStrings() && original === newed;

}

function(){

function strings(array) { return array;}function getStrings() { return strings`foo`;}var original = getStrings();var newed = new getStrings();return original === getStrings() && original === newed;

}

function(){

function strings(array) { return array;}var str = strings`\1\xz\uz\u{110000}\u{z}`;return str.length === 1 && str[0] === undefined && str.raw.length === 1 && str.raw[0]==="\\1\\xz\\uz\\u{110000}\\u{z}"

}

function(){

}

function(){

var re = new RegExp('\\w', 'y');re.exec('xy');return (re.exec('xy')[0] === 'y');

}

function(){

var re = new RegExp('\\w', 'y');re.exec('xy');return (re.exec('xy')[0] === 'y');

}

function(){

var re = new RegExp('yy', 'y');re.lastIndex = 3;var result = re.exec('xxxyyxx')[0];return result === 'yy' && re.lastIndex === 5;

}

function(){

var re = new RegExp('yy', 'y');re.lastIndex = 3;var result = re.exec('xxxyyxx')[0];return result === 'yy' && re.lastIndex === 5;

}

function(){

return "𠮷".match(/^.$/u)[0].length === 2;

}

function(){

return "𠮷".match(/^.$/u)[0].length === 2;

}

function(){

return "𠮷x".match(/^.x$/u)[0].length === 3;

}

function(){

return "𠮷x".match(/^.x$/u)[0].length === 3;

}

function(){

return "𝌆".match(/\u{1d306}/u)[0].length === 2;

}

function(){

return "𝌆".match(/\u{1d306}/u)[0].length === 2;

}

function(){

return "ſ".match(/S/iu) && "S".match(/ſ/iu);

}

function(){

return "ſ".match(/S/iu) && "S".match(/ſ/iu);

}

function(){

var [a, , [b], c] = [5, null, [6]];return a === 5 && b === 6 && c === void undefined;

}

function(){

var [a, , [b], c] = [5, null, [6]];return a === 5 && b === 6 && c === void undefined;

}

function(){

var [a, , b] = [,,,];return a === void undefined && b === void undefined;

}

function(){

var [a, , b] = [,,,];return a === void undefined && b === void undefined;

}

function(){

var [a, b, c] = "ab";return a === "a" && b === "b" && c === void undefined;

}

function(){

var [a, b, c] = "ab";return a === "a" && b === "b" && c === void undefined;

}

function(){

var [c] = "𠮷𠮶";return c === "𠮷";

}

function(){

var [c] = "𠮷𠮶";return c === "𠮷";

}

function(){

var [a, b, c] = (function*(){ yield 1; yield 2; }());return a === 1 && b === 2 && c === void undefined;

}

function(){

var [a, b, c] = (function*(){ yield 1; yield 2; }());return a === 1 && b === 2 && c === void undefined;

}

function(){

var [a, b, c] = global.__createIterableObject([1, 2]);return a === 1 && b === 2 && c === void undefined;

}

function(){

var [a, b, c] = global.__createIterableObject([1, 2]);return a === 1 && b === 2 && c === void undefined;

}

function(){

var [a, b, c] = Object.create(global.__createIterableObject([1, 2]));return a === 1 && b === 2 && c === void undefined;

}

function(){

var [a, b, c] = Object.create(global.__createIterableObject([1, 2]));return a === 1 && b === 2 && c === void undefined;

}

function(){

var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});var [a, b] = iter;return closed;

}

function(){

var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});var [a, b] = iter;return closed;

}

function(){

var [a,] = [1];return a === 1;

}

proper tail calls (tail call optimisation)
§direct recursion ? function(){ "use strict";return (function f(n){ if (n <= 0) { return "foo"; } return f(n - 1);}(1e6)) === "foo"; }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ "use strict";return (function f(n){ if (n <= 0) { return "foo"; } return f(n - 1);}(1e6)) === "foo"; }
§mutual recursion ? function(){ "use strict";function f(n){ if (n <= 0) { return "foo"; } return g(n - 1);}function g(n){ if (n <= 0) { return "bar"; } return f(n - 1);}return f(1e6) === "foo" && f(1e6+1) === "bar"; }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ "use strict";function f(n){ if (n <= 0) { return "foo"; } return g(n - 1);}function g(n){ if (n <= 0) { return "bar"; } return f(n - 1);}return f(1e6) === "foo" && f(1e6+1) === "bar"; }

const
§basic support ? function(){ const foo = 123;return (foo === 123); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ const foo = 123;return (foo === 123); }
§is block-scoped ? function(){ const bar = 123;{ const bar = 456; }return bar === 123; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ const bar = 123;{ const bar = 456; }return bar === 123; }
§scope shadow resolution ? function(){ try { { const bar = 456; } const bar = 123; return bar === 123;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ try { { const bar = 456; } const bar = 123; return bar === 123;} catch(e) { return false;} }
§cannot be in statements ? function(){ const bar = 1;try { Function("if(true) const baz = 1;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ const bar = 1;try { Function("if(true) const baz = 1;")();} catch(e) { return true;} }
§redefining a const is an error ? function(){ const baz = 1;try { Function("const foo = 1; foo = 2;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ const baz = 1;try { Function("const foo = 1; foo = 2;")();} catch(e) { return true;} }
§for loop statement scope ? function(){ const baz = 1;for(const baz = 0; false;) {}return baz === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ const baz = 1;for(const baz = 0; false;) {}return baz === 1; }
§for-in loop iteration scope ? function(){ var scopes = [];for(const i in { a:1, b:1 }) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error Error	Error Error
	function(){ var scopes = [];for(const i in { a:1, b:1 }) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }
§for-of loop iteration scope ? function(){ var scopes = [];for(const i of ['a','b']) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error Error	Error Error
	function(){ var scopes = [];for(const i of ['a','b']) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }
§temporal dead zone ? function(){ var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }const qux = 456;fn();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }const qux = 456;fn();return passed; }
§basic support (strict mode) ? function(){ "use strict";const foo = 123;return (foo === 123); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ "use strict";const foo = 123;return (foo === 123); }
§is block-scoped (strict mode) ? function(){ 'use strict';const bar = 123;{ const bar = 456; }return bar === 123; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';const bar = 123;{ const bar = 456; }return bar === 123; }
§scope shadow resolution (strict mode) ? function(){ 'use strict';try { { const bar = 456; } const bar = 123; return bar === 123;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';try { { const bar = 456; } const bar = 123; return bar === 123;} catch(e) { return false;} }
§cannot be in statements (strict mode) ? function(){ 'use strict';const bar = 1;try { Function("'use strict'; if(true) const baz = 1;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';const bar = 1;try { Function("'use strict'; if(true) const baz = 1;")();} catch(e) { return true;} }
§redefining a const (strict mode) ? function(){ 'use strict';const baz = 1;try { Function("'use strict'; const foo = 1; foo = 2;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';const baz = 1;try { Function("'use strict'; const foo = 1; foo = 2;")();} catch(e) { return true;} }
§for loop statement scope (strict mode) ? function(){ 'use strict';const baz = 1;for(const baz = 0; false;) {}return baz === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';const baz = 1;for(const baz = 0; false;) {}return baz === 1; }
§for-in loop iteration scope (strict mode) ? function(){ 'use strict';var scopes = [];for(const i in { a:1, b:1 }) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ 'use strict';var scopes = [];for(const i in { a:1, b:1 }) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }
§for-of loop iteration scope (strict mode) ? function(){ 'use strict';var scopes = [];for(const i of ['a','b']) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ 'use strict';var scopes = [];for(const i of ['a','b']) { scopes.push(function(){ return i; });}return (scopes[0]() === "a" && scopes[1]() === "b"); }
§temporal dead zone (strict mode) ? function(){ 'use strict';var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }const qux = 456;fn();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }const qux = 456;fn();return passed; }
let
§basic support ? function(){ let foo = 123;return (foo === 123); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ let foo = 123;return (foo === 123); }
§is block-scoped ? function(){ let bar = 123;{ let bar = 456; }return bar === 123; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ let bar = 123;{ let bar = 456; }return bar === 123; }
§scope shadow resolution ? function(){ try { { let bar = 456; } let bar = 123; return bar === 123;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ try { { let bar = 456; } let bar = 123; return bar === 123;} catch(e) { return false;} }
§cannot be in statements ? function(){ let bar = 1;try { Function("if(true) let baz = 1;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ let bar = 1;try { Function("if(true) let baz = 1;")();} catch(e) { return true;} }
§for loop statement scope ? function(){ let baz = 1;for(let baz = 0; false;) {}return baz === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ let baz = 1;for(let baz = 0; false;) {}return baz === 1; }
§temporal dead zone ? function(){ var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }let qux = 456;fn();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }let qux = 456;fn();return passed; }
§for/for-in loop iteration scope ? function(){ let scopes = [];for(let i = 0; i < 2; i++) { scopes.push(function(){ return i; });}let passed = (scopes[0]() === 0 && scopes[1]() === 1);scopes = [];for(let i in { a:1, b:1 }) { scopes.push(function(){ return i; });}passed &= (scopes[0]() === "a" && scopes[1]() === "b");return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ let scopes = [];for(let i = 0; i < 2; i++) { scopes.push(function(){ return i; });}let passed = (scopes[0]() === 0 && scopes[1]() === 1);scopes = [];for(let i in { a:1, b:1 }) { scopes.push(function(){ return i; });}passed &= (scopes[0]() === "a" && scopes[1]() === "b");return passed; }
§for-in loop binding shadowing parameter ? function(){ try { Function("function f(e) { for (let e in {}) e }"); return true;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ try { Function("function f(e) { for (let e in {}) e }"); return true;} catch(e) { return false;} }
§basic support (strict mode) ? function(){ 'use strict';let foo = 123;return (foo === 123); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';let foo = 123;return (foo === 123); }
§is block-scoped (strict mode) ? function(){ 'use strict';let bar = 123;{ let bar = 456; }return bar === 123; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';let bar = 123;{ let bar = 456; }return bar === 123; }
§scope shadow resolution (strict mode) ? function(){ 'use strict';try { { let bar = 456; } let bar = 123; return bar === 123;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';try { { let bar = 456; } let bar = 123; return bar === 123;} catch(e) { return false;} }
§cannot be in statements (strict mode) ? function(){ 'use strict';let bar = 1;try { Function("'use strict'; if(true) let baz = 1;")();} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';let bar = 1;try { Function("'use strict'; if(true) let baz = 1;")();} catch(e) { return true;} }
§for loop statement scope (strict mode) ? function(){ 'use strict';let baz = 1;for(let baz = 0; false;) {}return baz === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';let baz = 1;for(let baz = 0; false;) {}return baz === 1; }
§temporal dead zone (strict mode) ? function(){ 'use strict';var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }let qux = 456;fn();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';var passed = (function(){ try { qux; } catch(e) { return true; }}());function fn() { passed &= qux === 456; }let qux = 456;fn();return passed; }
§for/for-in loop iteration scope (strict mode) ? function(){ 'use strict';let scopes = [];for(let i = 0; i < 2; i++) { scopes.push(function(){ return i; });}let passed = (scopes[0]() === 0 && scopes[1]() === 1);scopes = [];for(let i in { a:1, b:1 }) { scopes.push(function(){ return i; });}passed &= (scopes[0]() === "a" && scopes[1]() === "b");return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error No
	function(){ 'use strict';let scopes = [];for(let i = 0; i < 2; i++) { scopes.push(function(){ return i; });}let passed = (scopes[0]() === 0 && scopes[1]() === 1);scopes = [];for(let i in { a:1, b:1 }) { scopes.push(function(){ return i; });}passed &= (scopes[0]() === "a" && scopes[1]() === "b");return passed; }
§for-in loop binding shadowing parameter (strict mode) ? function(){ try { Function("'use strict'; function f(e) { for (let e in {}) e }"); return true;} catch(e) { return false;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No Flag
	function(){ try { Function("'use strict'; function f(e) { for (let e in {}) e }"); return true;} catch(e) { return false;} }

§block-level function declaration ? function(){ 'use strict';if (f() !== 1) return false;function f() { return 1; }{ if (f() !== 2) return false; function f() { return 2; } if (f() !== 2) return false;}if (f() !== 1) return false;return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag
	function(){ 'use strict';if (f() !== 1) return false;function f() { return 1; }{ if (f() !== 2) return false; function f() { return 2; } if (f() !== 2) return false;}if (f() !== 1) return false;return true; }

arrow functions
§0 parameters ? function(){ return (() => 5)() === 5; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ return (() => 5)() === 5; }
§1 parameter, no brackets ? function(){ var b = x => x + "foo";return (b("fee fie foe ") === "fee fie foe foo"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var b = x => x + "foo";return (b("fee fie foe ") === "fee fie foe foo"); }
§multiple parameters ? function(){ var c = (v, w, x, y, z) => "" + v + w + x + y + z;return (c(6, 5, 4, 3, 2) === "65432"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var c = (v, w, x, y, z) => "" + v + w + x + y + z;return (c(6, 5, 4, 3, 2) === "65432"); }
§lexical "this" binding ? function(){ var d = { x : "bar", y : function() { return z => this.x + z; }}.y();var e = { x : "baz", y : d };return d("ley") === "barley" && e.y("ley") === "barley"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ var d = { x : "bar", y : function() { return z => this.x + z; }}.y();var e = { x : "baz", y : d };return d("ley") === "barley" && e.y("ley") === "barley"; }
§"this" unchanged by call or apply ? function(){ var d = { x : "foo", y : function() { return () => this.x; }};var e = { x : "bar" };return d.y().call(e) === "foo" && d.y().apply(e) === "foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ var d = { x : "foo", y : function() { return () => this.x; }};var e = { x : "bar" };return d.y().call(e) === "foo" && d.y().apply(e) === "foo"; }
§can't be bound, can be curried ? function(){ var d = { x : "bar", y : function() { return z => this.x + z; }};var e = { x : "baz" };return d.y().bind(e, "ley")() === "barley"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ var d = { x : "bar", y : function() { return z => this.x + z; }};var e = { x : "baz" };return d.y().bind(e, "ley")() === "barley"; }
§lexical "arguments" binding ? function(){ var f = (function() { return z => arguments[0]; }(5));return f(6) === 5; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ var f = (function() { return z => arguments[0]; }(5));return f(6) === 5; }
§no line break between params and => ? function(){ return (() => { try { Function("x\n => 2")(); } catch(e) { return true; }})(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ return (() => { try { Function("x\n => 2")(); } catch(e) { return true; }})(); }
§correct precedence ? function(){ return (() => { try { Function("0 \|\| () => 2")(); } catch(e) { return true; }})(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error No	Error Error
	function(){ return (() => { try { Function("0 \|\| () => 2")(); } catch(e) { return true; }})(); }
§no "prototype" property ? function(){ var a = () => 5;return !a.hasOwnProperty("prototype"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ var a = () => 5;return !a.hasOwnProperty("prototype"); }
§lexical "super" binding in constructors ? function(){ var received;class B { constructor (arg) { received = arg; }}class C extends B { constructor () { var callSuper = () => super('foo'); callSuper(); }}return new C instanceof C && received === 'foo' }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var received;class B { constructor (arg) { received = arg; }}class C extends B { constructor () { var callSuper = () => super('foo'); callSuper(); }}return new C instanceof C && received === 'foo' }
§lexical "super" binding in methods ? function(){ class B { qux() { return "quux"; }}class C extends B { baz() { return x => super.qux(); }}var arrow = new C().baz();return arrow() === "quux"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B { qux() { return "quux"; }}class C extends B { baz() { return x => super.qux(); }}var arrow = new C().baz();return arrow() === "quux"; }
§lexical "new.target" binding ? function(){ function C() { return x => new.target;}return new C()() === C && C()() === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error
	function(){ function C() { return x => new.target;}return new C()() === C && C()() === void undefined; }
class
§class statement ? function(){ class C {}return typeof C === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C {}return typeof C === "function"; }
§is block-scoped ? function(){ class C {}var c1 = C;{ class C {} var c2 = C;}return C === c1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C {}var c1 = C;{ class C {} var c2 = C;}return C === c1; }
§class expression ? function(){ return typeof class C {} === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return typeof class C {} === "function"; }
§anonymous class ? function(){ return typeof class {} === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return typeof class {} === "function"; }
§constructor ? function(){ class C { constructor() { this.x = 1; }}return C.prototype.constructor === C && new C().x === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { constructor() { this.x = 1; }}return C.prototype.constructor === C && new C().x === 1; }
§prototype methods ? function(){ class C { method() { return 2; }}return typeof C.prototype.method === "function" && new C().method() === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { method() { return 2; }}return typeof C.prototype.method === "function" && new C().method() === 2; }
§string-keyed methods ? function(){ class C { "foo bar"() { return 2; }}return typeof C.prototype["foo bar"] === "function" && new C()["foo bar"]() === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { "foo bar"() { return 2; }}return typeof C.prototype["foo bar"] === "function" && new C()["foo bar"]() === 2; }
§computed prototype methods ? function(){ var foo = "method";class C { [foo]() { return 2; }}return typeof C.prototype.method === "function" && new C().method() === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var foo = "method";class C { [foo]() { return 2; }}return typeof C.prototype.method === "function" && new C().method() === 2; }
§optional semicolons ? function(){ class C { ; method() { return 2; }; method2() { return 2; } method3() { return 2; };}return typeof C.prototype.method === "function" && typeof C.prototype.method2 === "function" && typeof C.prototype.method3 === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { ; method() { return 2; }; method2() { return 2; } method3() { return 2; };}return typeof C.prototype.method === "function" && typeof C.prototype.method2 === "function" && typeof C.prototype.method3 === "function"; }
§static methods ? function(){ class C { static method() { return 3; }}return typeof C.method === "function" && C.method() === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { static method() { return 3; }}return typeof C.method === "function" && C.method() === 3; }
§computed static methods ? function(){ var foo = "method";class C { static [foo]() { return 3; }}return typeof C.method === "function" && C.method() === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var foo = "method";class C { static [foo]() { return 3; }}return typeof C.method === "function" && C.method() === 3; }
§accessor properties ? function(){ var baz = false;class C { get foo() { return "foo"; } set bar(x) { baz = x; }}new C().bar = true;return new C().foo === "foo" && baz; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var baz = false;class C { get foo() { return "foo"; } set bar(x) { baz = x; }}new C().bar = true;return new C().foo === "foo" && baz; }
§computed accessor properties ? function(){ var garply = "foo", grault = "bar", baz = false;class C { get [garply]() { return "foo"; } set [grault](x) { baz = x; }}new C().bar = true;return new C().foo === "foo" && baz; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var garply = "foo", grault = "bar", baz = false;class C { get [garply]() { return "foo"; } set [grault](x) { baz = x; }}new C().bar = true;return new C().foo === "foo" && baz; }
§static accessor properties ? function(){ var baz = false;class C { static get foo() { return "foo"; } static set bar(x) { baz = x; }}C.bar = true;return C.foo === "foo" && baz; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var baz = false;class C { static get foo() { return "foo"; } static set bar(x) { baz = x; }}C.bar = true;return C.foo === "foo" && baz; }
§computed static accessor properties ? function(){ var garply = "foo", grault = "bar", baz = false;class C { static get [garply]() { return "foo"; } static set [grault](x) { baz = x; }}C.bar = true;return C.foo === "foo" && baz; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var garply = "foo", grault = "bar", baz = false;class C { static get [garply]() { return "foo"; } static set [grault](x) { baz = x; }}C.bar = true;return C.foo === "foo" && baz; }
§class name is lexically scoped ? function(){ class C { method() { return typeof C === "function"; }}var M = C.prototype.method;C = void undefined;return C === void undefined && M(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { method() { return typeof C === "function"; }}var M = C.prototype.method;C = void undefined;return C === void undefined && M(); }
§computed names, temporal dead zone ? function(){ try { var B = class C { [C](){} }} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ try { var B = class C { [C](){} }} catch(e) { return true;} }
§methods aren't enumerable ? function(){ class C { foo() {} static bar() {}}return !C.prototype.propertyIsEnumerable("foo") && !C.propertyIsEnumerable("bar"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { foo() {} static bar() {}}return !C.prototype.propertyIsEnumerable("foo") && !C.propertyIsEnumerable("bar"); }
§implicit strict mode ? function(){ class C { static method() { return this === void undefined; }}return (0,C.method)(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { static method() { return this === void undefined; }}return (0,C.method)(); }
§constructor requires new ? function(){ class C {}try { C();}catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C {}try { C();}catch(e) { return true;} }
§extends ? function(){ class B {}class C extends B {}return new C() instanceof B && B.isPrototypeOf(C); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B {}class C extends B {}return new C() instanceof B && B.isPrototypeOf(C); }
§extends expressions ? function(){ var B;class C extends (B = class {}) {}return new C() instanceof B && B.isPrototypeOf(C); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var B;class C extends (B = class {}) {}return new C() instanceof B && B.isPrototypeOf(C); }
§extends null ? function(){ class C extends null { constructor() { return Object.create(null); }}return Function.prototype.isPrototypeOf(C) && Object.getPrototypeOf(C.prototype) === null; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends null { constructor() { return Object.create(null); }}return Function.prototype.isPrototypeOf(C) && Object.getPrototypeOf(C.prototype) === null; }
§new.target ? function(){ var passed = false;new function f() { passed = new.target === f;}();class A { constructor() { passed &= new.target === B; }}class B extends A {}new B();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var passed = false;new function f() { passed = new.target === f;}();class A { constructor() { passed &= new.target === B; }}class B extends A {}new B();return passed; }
super
§statement in constructors ? function(){ var passed = false;class B { constructor(a) { passed = (a === "barbaz"); }}class C extends B { constructor(a) { super("bar" + a); }}new C("baz");return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var passed = false;class B { constructor(a) { passed = (a === "barbaz"); }}class C extends B { constructor(a) { super("bar" + a); }}new C("baz");return passed; }
§expression in constructors ? function(){ class B { constructor(a) { return ["foo" + a]; }}class C extends B { constructor(a) { return super("bar" + a); }}return new C("baz")[0] === "foobarbaz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B { constructor(a) { return ["foo" + a]; }}class C extends B { constructor(a) { return super("bar" + a); }}return new C("baz")[0] === "foobarbaz"; }
§in methods, property access ? function(){ class B {}B.prototype.qux = "foo";B.prototype.corge = "baz";class C extends B { quux(a) { return super.qux + a + super["corge"]; }}C.prototype.qux = "garply";return new C().quux("bar") === "foobarbaz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B {}B.prototype.qux = "foo";B.prototype.corge = "baz";class C extends B { quux(a) { return super.qux + a + super["corge"]; }}C.prototype.qux = "garply";return new C().quux("bar") === "foobarbaz"; }
§in methods, method calls ? function(){ class B { qux(a) { return "foo" + a; }}class C extends B { qux(a) { return super.qux("bar" + a); }}return new C().qux("baz") === "foobarbaz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B { qux(a) { return "foo" + a; }}class C extends B { qux(a) { return super.qux("bar" + a); }}return new C().qux("baz") === "foobarbaz"; }
§method calls use correct "this" binding ? function(){ class B { qux(a) { return this.foo + a; }}class C extends B { qux(a) { return super.qux("bar" + a); }}var obj = new C();obj.foo = "foo";return obj.qux("baz") === "foobarbaz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B { qux(a) { return this.foo + a; }}class C extends B { qux(a) { return super.qux("bar" + a); }}var obj = new C();obj.foo = "foo";return obj.qux("baz") === "foobarbaz"; }
§constructor calls use correct "new.target" binding ? function(){ var passed;class B { constructor() { passed = (new.target === C); }}class C extends B { constructor() { super(); }}new C();return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var passed;class B { constructor() { passed = (new.target === C); }}class C extends B { constructor() { super(); }}new C();return passed; }
§is statically bound ? function(){ class B { qux() { return "bar"; }}class C extends B { qux() { return super.qux() + this.corge; }}var obj = { qux: C.prototype.qux, corge: "ley"};return obj.qux() === "barley"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class B { qux() { return "bar"; }}class C extends B { qux() { return super.qux() + this.corge; }}var obj = { qux: C.prototype.qux, corge: "ley"};return obj.qux() === "barley"; }
§super() invokes the correct constructor ? function(){ // checks that super() is not a synonym of super.constructor()var passed;class B { constructor() { passed = true; }};B.prototype.constructor = function () { passed = false;};class C extends B { };new C;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ // checks that super() is not a synonym of super.constructor()var passed;class B { constructor() { passed = true; }};B.prototype.constructor = function () { passed = false;};class C extends B { };new C;return passed; }
generators
§basic functionality ? function(){ function * generator(){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ function * generator(){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§generator function expressions ? function(){ var generator = function * (){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var generator = function * (){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§correct "this" binding ? function(){ function * generator(){ yield this.x; yield this.y;};var iterator = { g: generator, x: 5, y: 6 }.g();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ function * generator(){ yield this.x; yield this.y;};var iterator = { g: generator, x: 5, y: 6 }.g();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§can't use "this" with new ? function(){ function * generator(){ yield this.x; yield this.y;};try { (new generator()).next();}catch (e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error No	Error Error
	function(){ function * generator(){ yield this.x; yield this.y;};try { (new generator()).next();}catch (e) { return true;} }
§sending ? function(){ var sent;function * generator(){ sent = [yield 5, yield 6];};var iterator = generator();iterator.next();iterator.next("foo");iterator.next("bar");return sent[0] === "foo" && sent[1] === "bar"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var sent;function * generator(){ sent = [yield 5, yield 6];};var iterator = generator();iterator.next();iterator.next("foo");iterator.next("bar");return sent[0] === "foo" && sent[1] === "bar"; }
§%GeneratorPrototype% ? function(){ function * generatorFn(){}var ownProto = Object.getPrototypeOf(generatorFn());var passed = ownProto === generatorFn.prototype;var sharedProto = Object.getPrototypeOf(ownProto);passed &= sharedProto !== Object.prototype && sharedProto === Object.getPrototypeOf(function*(){}.prototype) && sharedProto.hasOwnProperty('next');return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ function * generatorFn(){}var ownProto = Object.getPrototypeOf(generatorFn());var passed = ownProto === generatorFn.prototype;var sharedProto = Object.getPrototypeOf(ownProto);passed &= sharedProto !== Object.prototype && sharedProto === Object.getPrototypeOf(function*(){}.prototype) && sharedProto.hasOwnProperty('next');return passed; }
§%GeneratorPrototype% prototype chain ? function(){ function * generatorFn(){}var g = generatorFn();var ownProto = Object.getPrototypeOf(g);var passed = ownProto === generatorFn.prototype;var sharedProto = Object.getPrototypeOf(ownProto);var iterProto = Object.getPrototypeOf(sharedProto);passed &= iterProto.hasOwnProperty(Symbol.iterator) && !sharedProto .hasOwnProperty(Symbol.iterator) && !ownProto .hasOwnProperty(Symbol.iterator) && g[Symbol.iterator]() === g;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error
	function(){ function * generatorFn(){}var g = generatorFn();var ownProto = Object.getPrototypeOf(g);var passed = ownProto === generatorFn.prototype;var sharedProto = Object.getPrototypeOf(ownProto);var iterProto = Object.getPrototypeOf(sharedProto);passed &= iterProto.hasOwnProperty(Symbol.iterator) && !sharedProto .hasOwnProperty(Symbol.iterator) && !ownProto .hasOwnProperty(Symbol.iterator) && g[Symbol.iterator]() === g;return passed; }
§%GeneratorPrototype%.constructor ? function(){ function * g (){}var iterator = new g.constructor("a","b","c","yield a; yield b; yield c;")(5,6,7);var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;passed &= g.constructor === (function*(){}).constructor;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ function * g (){}var iterator = new g.constructor("a","b","c","yield a; yield b; yield c;")(5,6,7);var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;passed &= g.constructor === (function*(){}).constructor;return passed; }
§%GeneratorPrototype%.throw ? function(){ var passed = false;function * generator(){ try { yield 5; yield 6; } catch(e) { passed = (e === "foo"); }};var iterator = generator();iterator.next();iterator.throw("foo");return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var passed = false;function * generator(){ try { yield 5; yield 6; } catch(e) { passed = (e === "foo"); }};var iterator = generator();iterator.next();iterator.throw("foo");return passed; }
§%GeneratorPrototype%.return ? function(){ function * generator(){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.return("quxquux");passed &= item.value === "quxquux" && item.done === true;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ function * generator(){ yield 5; yield 6;};var iterator = generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.return("quxquux");passed &= item.value === "quxquux" && item.done === true;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield operator precedence ? function(){ var passed;function * generator(){ passed = yield 0 ? true : false;};var iterator = generator();iterator.next();iterator.next(true);return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var passed;function * generator(){ passed = yield 0 ? true : false;};var iterator = generator();iterator.next();iterator.next(true);return passed; }
§yield , arrays ? function(){ var iterator = (function generator() { yield * [5, 6];}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * [5, 6];}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , sparse arrays ? function(){ var iterator = (function generator() { yield * [,,];}());var item = iterator.next();var passed = item.value === void undefined && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * [,,];}());var item = iterator.next();var passed = item.value === void undefined && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , strings ? function(){ var iterator = (function generator() { yield * "56";}());var item = iterator.next();var passed = item.value === "5" && item.done === false;item = iterator.next();passed &= item.value === "6" && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * "56";}());var item = iterator.next();var passed = item.value === "5" && item.done === false;item = iterator.next();passed &= item.value === "6" && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , astral plane strings ? function(){ var iterator = (function generator() { yield * "𠮷𠮶";}());var item = iterator.next();var passed = item.value === "𠮷" && item.done === false;item = iterator.next();passed &= item.value === "𠮶" && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * "𠮷𠮶";}());var item = iterator.next();var passed = item.value === "𠮷" && item.done === false;item = iterator.next();passed &= item.value === "𠮶" && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , generator instances ? function(){ var iterator = (function generator() { yield * (function*(){ yield 5; yield 6; yield 7; }());}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * (function*(){ yield 5; yield 6; yield 7; }());}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , generic iterables ? function(){ var iterator = (function generator() { yield * global.__createIterableObject([5, 6, 7]);}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * global.__createIterableObject([5, 6, 7]);}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield , instances of iterables ? function(){ var iterator = (function generator() { yield * Object.create(__createIterableObject([5, 6, 7]));}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * Object.create(__createIterableObject([5, 6, 7]));}());var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === 7 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§yield * on non-iterables is a runtime error ? function(){ var iterator = (function * generator() { yield * [5];}());var item = iterator.next();var passed = item.value === 5 && item.done === false;iterator = (function * generator() { yield * 5;}());try { iterator.next();} catch (e) { return passed;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var iterator = (function * generator() { yield * [5];}());var item = iterator.next();var passed = item.value === 5 && item.done === false;iterator = (function * generator() { yield * 5;}());try { iterator.next();} catch (e) { return passed;} }
§yield , iterator closing ? function(){ var closed = '';var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed += 'a'; return {done: true}; }});var gen = (function generator(){ try { yield *iter; } finally { closed += 'b'; }})();gen.next();gen['return']();return closed === 'ab'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ var closed = '';var iter = __createIterableObject([1, 2, 3], { 'return': function(){ closed += 'a'; return {done: true}; }});var gen = (function* generator(){ try { yield *iter; } finally { closed += 'b'; }})();gen.next();gen['return']();return closed === 'ab'; }
§yield , iterator closing via throw() ? function(){ var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'throw': undefined, 'return': function() { closed = true; return {done: true}; }});var gen = (function(){ try { yield *iter; } catch(e){}})();gen.next();gen['throw']();return closed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error No	Error Error
	function(){ var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'throw': undefined, 'return': function() { closed = true; return {done: true}; }});var gen = (function(){ try { yield iter; } catch(e){}})();gen.next();gen['throw']();return closed; }
§shorthand generator methods ? function(){ var o = { * generator() { yield 5; yield 6; }};var iterator = o.generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var o = { * generator() { yield 5; yield 6; }};var iterator = o.generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§string-keyed shorthand generator methods ? function(){ var o = { * "foo bar"() { yield 5; yield 6; }};var iterator = o["foo bar"]();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var o = { * "foo bar"() { yield 5; yield 6; }};var iterator = o["foo bar"]();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§computed shorthand generators ? function(){ var garply = "generator";var o = { * [garply] () { yield 5; yield 6; }};var iterator = o.generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var garply = "generator";var o = { * [garply] () { yield 5; yield 6; }};var iterator = o.generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§shorthand generator methods, classes ? function(){ class C { * generator() { yield 5; yield 6; }};var iterator = new C().generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { * generator() { yield 5; yield 6; }};var iterator = new C().generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§computed shorthand generators, classes ? function(){ var garply = "generator";class C { * [garply] () { yield 5; yield 6; }}var iterator = new C().generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var garply = "generator";class C { * [garply] () { yield 5; yield 6; }}var iterator = new C().generator();var item = iterator.next();var passed = item.value === 5 && item.done === false;item = iterator.next();passed &= item.value === 6 && item.done === false;item = iterator.next();passed &= item.value === void undefined && item.done === true;return passed; }
§shorthand generators can't be constructors ? function(){ class C { * generator() { yield 5; yield 6; }};try { Function("class D { * constructor() { return {}; } }");} catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { * generator() { yield 5; yield 6; }};try { Function("class D { * constructor() { return {}; } }");} catch(e) { return true;} }

Object static methods
§Object.assign ? function(){ var o = Object.assign({a:true}, {b:true}, {c:true});return "a" in o && "b" in o && "c" in o; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var o = Object.assign({a:true}, {b:true}, {c:true});return "a" in o && "b" in o && "c" in o; }
§Object.is ? function(){ return typeof Object.is === 'function' && Object.is(NaN, NaN) && !Object.is(-0, 0); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return typeof Object.is === 'function' && Object.is(NaN, NaN) && !Object.is(-0, 0); }
§Object.getOwnPropertySymbols ? function(){ var o = {};var sym = Symbol(), sym2 = Symbol(), sym3 = Symbol();o[sym] = true;o[sym2] = true;o[sym3] = true;var result = Object.getOwnPropertySymbols(o);return result[0] === sym && result[1] === sym2 && result[2] === sym3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ var o = {};var sym = Symbol(), sym2 = Symbol(), sym3 = Symbol();o[sym] = true;o[sym2] = true;o[sym3] = true;var result = Object.getOwnPropertySymbols(o);return result[0] === sym && result[1] === sym2 && result[2] === sym3; }
§Object.setPrototypeOf ? function(){ return Object.setPrototypeOf({}, Array.prototype) instanceof Array; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ return Object.setPrototypeOf({}, Array.prototype) instanceof Array; }
function "name" property
§function statements ? function(){ function foo(){};return foo.name === 'foo' && (function(){}).name === ''; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ function foo(){};return foo.name === 'foo' && (function(){}).name === ''; }
§function expressions ? function(){ return (function foo(){}).name === 'foo' && (function(){}).name === ''; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return (function foo(){}).name === 'foo' && (function(){}).name === ''; }
§new Function ? function(){ return (new Function).name === "anonymous"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ return (new Function).name === "anonymous"; }
§bound functions ? function(){ function foo() {};return foo.bind({}).name === "bound foo" && (function(){}).bind({}).name === "bound "; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ function foo() {};return foo.bind({}).name === "bound foo" && (function(){}).bind({}).name === "bound "; }
§variables (function) ? function(){ var foo = function() {};var bar = function baz() {};return foo.name === "foo" && bar.name === "baz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	No No	No No
	function(){ var foo = function() {};var bar = function baz() {};return foo.name === "foo" && bar.name === "baz"; }
§object methods (function) ? function(){ var o = { foo: function(){}, bar: function baz(){}};o.qux = function(){};return o.foo.name === "foo" && o.bar.name === "baz" && o.qux.name === ""; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	No No	No No
	function(){ var o = { foo: function(){}, bar: function baz(){}};o.qux = function(){};return o.foo.name === "foo" && o.bar.name === "baz" && o.qux.name === ""; }
§accessor properties ? function(){ var o = { get foo(){}, set foo(x){} };var descriptor = Object.getOwnPropertyDescriptor(o, "foo");return descriptor.get.name === "get foo" && descriptor.set.name === "set foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	No No	No No
	function(){ var o = { get foo(){}, set foo(x){} };var descriptor = Object.getOwnPropertyDescriptor(o, "foo");return descriptor.get.name === "get foo" && descriptor.set.name === "set foo"; }
§shorthand methods ? function(){ var o = { foo(){} };return o.foo.name === "foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var o = { foo(){} };return o.foo.name === "foo"; }
§shorthand methods (no lexical binding) ? function(){ var f = "foo";return ({f() { return f; }}).f() === "foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var f = "foo";return ({f() { return f; }}).f() === "foo"; }
§symbol-keyed methods ? function(){ var sym1 = Symbol("foo");var sym2 = Symbol();var o = { [sym1]: function(){}, [sym2]: function(){}};return o[sym1].name === "[foo]" && o[sym2].name === ""; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	Error Error	Error Error
	function(){ var sym1 = Symbol("foo");var sym2 = Symbol();var o = { [sym1]: function(){}, [sym2]: function(){}};return o[sym1].name === "[foo]" && o[sym2].name === ""; }
§class statements ? function(){ class foo {};class bar { static name() {} };return foo.name === "foo" && typeof bar.name === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class foo {};class bar { static name() {} };return foo.name === "foo" && typeof bar.name === "function"; }
§class expressions ? function(){ return class foo {}.name === "foo" && typeof class bar { static name() {} }.name === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return class foo {}.name === "foo" && typeof class bar { static name() {} }.name === "function"; }
§variables (class) ? function(){ var foo = class {};var bar = class baz {};var qux = class { static name() {} };return foo.name === "foo" && bar.name === "baz" && typeof qux.name === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ var foo = class {};var bar = class baz {};var qux = class { static name() {} };return foo.name === "foo" && bar.name === "baz" && typeof qux.name === "function"; }
§object methods (class) ? function(){ var o = { foo: class {}, bar: class baz {}};o.qux = class {};return o.foo.name === "foo" && o.bar.name === "baz" && o.qux.name === ""; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ var o = { foo: class {}, bar: class baz {}};o.qux = class {};return o.foo.name === "foo" && o.bar.name === "baz" && o.qux.name === ""; }
§class prototype methods ? function(){ class C { foo(){} };return (new C).foo.name === "foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { foo(){} };return (new C).foo.name === "foo"; }
§class static methods ? function(){ class C { static foo(){} };return C.foo.name === "foo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C { static foo(){} };return C.foo.name === "foo"; }
§isn't writable, is configurable ? function(){ var descriptor = Object.getOwnPropertyDescriptor(function f(){},"name");return descriptor.enumerable === false && descriptor.writable === false && descriptor.configurable === true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ var descriptor = Object.getOwnPropertyDescriptor(function f(){},"name");return descriptor.enumerable === false && descriptor.writable === false && descriptor.configurable === true; }
String static methods
§String.raw ? function(){ return typeof String.raw === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ return typeof String.raw === 'function'; }
§String.fromCodePoint ? function(){ return typeof String.fromCodePoint === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof String.fromCodePoint === 'function'; }
String.prototype methods
§String.prototype.codePointAt ? function(){ return typeof String.prototype.codePointAt === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof String.prototype.codePointAt === 'function'; }
§String.prototype.normalize ? function(){ return typeof String.prototype.normalize === "function" && "c\u0327\u0301".normalize("NFC") === "\u1e09" && "\u1e09".normalize("NFD") === "c\u0327\u0301"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof String.prototype.normalize === "function" && "c\u0327\u0301".normalize("NFC") === "\u1e09" && "\u1e09".normalize("NFD") === "c\u0327\u0301"; }
§String.prototype.repeat ? function(){ return typeof String.prototype.repeat === 'function' && "foo".repeat(3) === "foofoofoo"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof String.prototype.repeat === 'function' && "foo".repeat(3) === "foofoofoo"; }
§String.prototype.startsWith ? function(){ return typeof String.prototype.startsWith === 'function' && "foobar".startsWith("foo"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof String.prototype.startsWith === 'function' && "foobar".startsWith("foo"); }
§String.prototype.startsWith throws on RegExp ? function(){ try { "a".startsWith(/./);} catch(e) { return typeof String.prototype.startsWith === 'function';} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ try { "a".startsWith(/./);} catch(e) { return typeof String.prototype.startsWith === 'function';} }
§String.prototype.endsWith ? function(){ return typeof String.prototype.endsWith === 'function' && "foobar".endsWith("bar"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof String.prototype.endsWith === 'function' && "foobar".endsWith("bar"); }
§String.prototype.endsWith throws on RegExp ? function(){ try { "a".endsWith(/./);} catch(e) { return typeof String.prototype.endsWith === 'function';} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ try { "a".endsWith(/./);} catch(e) { return typeof String.prototype.endsWith === 'function';} }
§String.prototype.includes ? function(){ return typeof String.prototype.includes === 'function' && "foobar".includes("oba"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ return typeof String.prototype.includes === 'function' && "foobar".includes("oba"); }
§String.prototype[Symbol.iterator] ? function(){ return typeof String.prototype[Symbol.iterator] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ return typeof String.prototype[Symbol.iterator] === 'function'; }
§String iterator prototype chain ? function(){ // Iterator instancevar iterator = ''[Symbol.iterator]();// %StringIteratorPrototype%var proto1 = Object.getPrototypeOf(iterator);// %IteratorPrototype%var proto2 = Object.getPrototypeOf(proto1);return proto2.hasOwnProperty(Symbol.iterator) && !proto1 .hasOwnProperty(Symbol.iterator) && !iterator .hasOwnProperty(Symbol.iterator) && iterator[Symbol.iterator]() === iterator; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	Error Error
	function(){ // Iterator instancevar iterator = ''[Symbol.iterator]();// %StringIteratorPrototype%var proto1 = Object.getPrototypeOf(iterator);// %IteratorPrototype%var proto2 = Object.getPrototypeOf(proto1);return proto2.hasOwnProperty(Symbol.iterator) && !proto1 .hasOwnProperty(Symbol.iterator) && !iterator .hasOwnProperty(Symbol.iterator) && iterator[Symbol.iterator]() === iterator; }
RegExp.prototype properties
§RegExp.prototype.flags ? function(){ return /./igm.flags === "gim" && /./.flags === ""; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ return /./igm.flags === "gim" && /./.flags === ""; }
§RegExp.prototype[Symbol.match] ? function(){ return typeof RegExp.prototype[Symbol.match] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	Error Error
	function(){ return typeof RegExp.prototype[Symbol.match] === 'function'; }
§RegExp.prototype[Symbol.replace] ? function(){ return typeof RegExp.prototype[Symbol.replace] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	Error Error
	function(){ return typeof RegExp.prototype[Symbol.replace] === 'function'; }
§RegExp.prototype[Symbol.split] ? function(){ return typeof RegExp.prototype[Symbol.split] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	Error Error
	function(){ return typeof RegExp.prototype[Symbol.split] === 'function'; }
§RegExp.prototype[Symbol.search] ? function(){ return typeof RegExp.prototype[Symbol.search] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	Error Error
	function(){ return typeof RegExp.prototype[Symbol.search] === 'function'; }
§RegExp[Symbol.species] ? function(){ var prop = Object.getOwnPropertyDescriptor(RegExp, Symbol.species);return 'get' in prop && RegExp[Symbol.species] === RegExp; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error
	function(){ var prop = Object.getOwnPropertyDescriptor(RegExp, Symbol.species);return 'get' in prop && RegExp[Symbol.species] === RegExp; }
Array static methods
§Array.from, array-like objects ? function(){ return Array.from({ 0: "foo", 1: "bar", length: 2 }) + '' === "foo,bar"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ return Array.from({ 0: "foo", 1: "bar", length: 2 }) + '' === "foo,bar"; }
§Array.from, generator instances ? function(){ var iterable = (function*(){ yield 1; yield 2; yield 3; }());return Array.from(iterable) + '' === "1,2,3"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = (function*(){ yield 1; yield 2; yield 3; }());return Array.from(iterable) + '' === "1,2,3"; }
§Array.from, generic iterables ? function(){ var iterable = global.__createIterableObject([1, 2, 3]);return Array.from(iterable) + '' === "1,2,3"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = global.__createIterableObject([1, 2, 3]);return Array.from(iterable) + '' === "1,2,3"; }
§Array.from, instances of generic iterables ? function(){ var iterable = global.__createIterableObject([1, 2, 3]);return Array.from(Object.create(iterable)) + '' === "1,2,3"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = global.__createIterableObject([1, 2, 3]);return Array.from(Object.create(iterable)) + '' === "1,2,3"; }
§Array.from map function, array-like objects ? function(){ return Array.from({ 0: "foo", 1: "bar", length: 2 }, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ return Array.from({ 0: "foo", 1: "bar", length: 2 }, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1"; }
§Array.from map function, generator instances ? function(){ var iterable = (function*(){ yield "foo"; yield "bar"; yield "bal"; }());return Array.from(iterable, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = (function*(){ yield "foo"; yield "bar"; yield "bal"; }());return Array.from(iterable, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }
§Array.from map function, generic iterables ? function(){ var iterable = global.__createIterableObject(["foo", "bar", "bal"]);return Array.from(iterable, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = global.__createIterableObject(["foo", "bar", "bal"]);return Array.from(iterable, function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }
§Array.from map function, instances of iterables ? function(){ var iterable = global.__createIterableObject(["foo", "bar", "bal"]);return Array.from(Object.create(iterable), function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ var iterable = global.__createIterableObject(["foo", "bar", "bal"]);return Array.from(Object.create(iterable), function(e, i) { return e + this.baz + i;}, { baz: "d" }) + '' === "food0,bard1,bald2"; }
§Array.from, iterator closing ? function(){ var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});try { Array.from(iter, function() { throw 42 });} catch(e){}return closed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No
	function(){ var closed = false;var iter = global.__createIterableObject([1, 2, 3], { 'return': function(){ closed = true; return {}; }});try { Array.from(iter, function() { throw 42 });} catch(e){}return closed; }
§Array.of ? function(){ return typeof Array.of === 'function' && Array.of(2)[0] === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ return typeof Array.of === 'function' && Array.of(2)[0] === 2; }
§Array[Symbol.species] ? function(){ var prop = Object.getOwnPropertyDescriptor(Array, Symbol.species);return 'get' in prop && Array[Symbol.species] === Array; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error
	function(){ var prop = Object.getOwnPropertyDescriptor(Array, Symbol.species);return 'get' in prop && Array[Symbol.species] === Array; }
Array.prototype methods
§Array.prototype.copyWithin ? function(){ return typeof Array.prototype.copyWithin === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ return typeof Array.prototype.copyWithin === 'function'; }
§Array.prototype.find ? function(){ return typeof Array.prototype.find === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof Array.prototype.find === 'function'; }
§Array.prototype.findIndex ? function(){ return typeof Array.prototype.findIndex === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof Array.prototype.findIndex === 'function'; }
§Array.prototype.fill ? function(){ return typeof Array.prototype.fill === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No
	function(){ return typeof Array.prototype.fill === 'function'; }
§Array.prototype.keys ? function(){ return typeof Array.prototype.keys === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Array.prototype.keys === 'function'; }
§Array.prototype.values ? function(){ return typeof Array.prototype.values === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Yes Yes	No No
	function(){ return typeof Array.prototype.values === 'function'; }
§Array.prototype.entries ? function(){ return typeof Array.prototype.entries === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Array.prototype.entries === 'function'; }
§Array.prototype.splice ? function(){ if ([0, 1, 2].splice(0).length !== 3) { // IE <= 8 and other pre-ES6 engines fail this check return false;}var a = [1, 2];var result = a.splice();if (a.length !== 2 \|\| result.length !== 0) { // Safari 5.0 has this bug return false;}var obj = {};Array.prototype.splice.call(obj, 0, 0, 1);if (obj.length !== 1) { return false;}var spliceWorksWithLargeSparseArrays = (function () { // Per https://github.com/es-shims/es5-shim/issues/295 // Safari 7/8 breaks with sparse arrays of size 1e5 or greater var arr = new Array(1e5); // note: the index MUST be 8 or larger or the test will false pass arr[8] = 'x'; arr.splice(1, 1); for (var i = 0; i < arr.length; i += 1) { if (arr[i] === 'x') { return i === 7; } } return false;}());var spliceWorksWithSmallSparseArrays = (function () { // Per https://github.com/es-shims/es5-shim/issues/295 // Opera 12.15 breaks on this, no idea why. var n = 256; var arr = []; arr[n] = 'a'; arr.splice(n + 1, 0, 'b'); return arr[n] === 'a';}());return spliceWorksWithLargeSparseArrays && spliceWorksWithSmallSparseArrays; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ if ([0, 1, 2].splice(0).length !== 3) { // IE <= 8 and other pre-ES6 engines fail this check return false;}var a = [1, 2];var result = a.splice();if (a.length !== 2 \|\| result.length !== 0) { // Safari 5.0 has this bug return false;}var obj = {};Array.prototype.splice.call(obj, 0, 0, 1);if (obj.length !== 1) { return false;}var spliceWorksWithLargeSparseArrays = (function () { // Per https://github.com/es-shims/es5-shim/issues/295 // Safari 7/8 breaks with sparse arrays of size 1e5 or greater var arr = new Array(1e5); // note: the index MUST be 8 or larger or the test will false pass arr[8] = 'x'; arr.splice(1, 1); for (var i = 0; i < arr.length; i += 1) { if (arr[i] === 'x') { return i === 7; } } return false;}());var spliceWorksWithSmallSparseArrays = (function () { // Per https://github.com/es-shims/es5-shim/issues/295 // Opera 12.15 breaks on this, no idea why. var n = 256; var arr = []; arr[n] = 'a'; arr.splice(n + 1, 0, 'b'); return arr[n] === 'a';}());return spliceWorksWithLargeSparseArrays && spliceWorksWithSmallSparseArrays; }
§Array.prototype[Symbol.iterator] ? function(){ return typeof Array.prototype[Symbol.iterator] === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ return typeof Array.prototype[Symbol.iterator] === 'function'; }
§Array iterator prototype chain ? function(){ // Iterator instancevar iterator = [][Symbol.iterator]();// %ArrayIteratorPrototype%var proto1 = Object.getPrototypeOf(iterator);// %IteratorPrototype%var proto2 = Object.getPrototypeOf(proto1);return proto2.hasOwnProperty(Symbol.iterator) && !proto1 .hasOwnProperty(Symbol.iterator) && !iterator .hasOwnProperty(Symbol.iterator) && iterator[Symbol.iterator]() === iterator; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	Error Error
	function(){ // Iterator instancevar iterator = [][Symbol.iterator]();// %ArrayIteratorPrototype%var proto1 = Object.getPrototypeOf(iterator);// %IteratorPrototype%var proto2 = Object.getPrototypeOf(proto1);return proto2.hasOwnProperty(Symbol.iterator) && !proto1 .hasOwnProperty(Symbol.iterator) && !iterator .hasOwnProperty(Symbol.iterator) && iterator[Symbol.iterator]() === iterator; }
§Array.prototype[Symbol.unscopables] ? function(){ var unscopables = Array.prototype[Symbol.unscopables];if (!unscopables) { return false;}var ns = "find,findIndex,fill,copyWithin,entries,keys,values".split(",");for (var i = 0; i < ns.length; i++) { if (Array.prototype[ns[i]] && !unscopables[ns[i]]) return false;}return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ var unscopables = Array.prototype[Symbol.unscopables];if (!unscopables) { return false;}var ns = "find,findIndex,fill,copyWithin,entries,keys,values".split(",");for (var i = 0; i < ns.length; i++) { if (Array.prototype[ns[i]] && !unscopables[ns[i]]) return false;}return true; }
Number properties
§Number.isFinite ? function(){ return typeof Number.isFinite === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return typeof Number.isFinite === 'function'; }
§Number.isInteger ? function(){ return typeof Number.isInteger === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Number.isInteger === 'function'; }
§Number.isSafeInteger ? function(){ return typeof Number.isSafeInteger === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Number.isSafeInteger === 'function'; }
§Number.isNaN ? function(){ return typeof Number.isNaN === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return typeof Number.isNaN === 'function'; }
§Number.parseFloat ? function(){ var actualGlobal = Function('return this')();return typeof Number.parseFloat === 'function' && Number.parseFloat === actualGlobal.parseFloat; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ var actualGlobal = Function('return this')();return typeof Number.parseFloat === 'function' && Number.parseFloat === actualGlobal.parseFloat; }
§Number.parseInt ? function(){ var actualGlobal = Function('return this')();return typeof Number.parseInt === 'function' && Number.parseInt === actualGlobal.parseInt; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ var actualGlobal = Function('return this')();return typeof Number.parseInt === 'function' && Number.parseInt === actualGlobal.parseInt; }
§Number.EPSILON ? function(){ return typeof Number.EPSILON === 'number'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Number.EPSILON === 'number'; }
§Number.MIN_SAFE_INTEGER ? function(){ return typeof Number.MIN_SAFE_INTEGER === 'number'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Number.MIN_SAFE_INTEGER === 'number'; }
§Number.MAX_SAFE_INTEGER ? function(){ return typeof Number.MAX_SAFE_INTEGER === 'number'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Number.MAX_SAFE_INTEGER === 'number'; }
Math methods
§Math.clz32 ? function(){ return typeof Math.clz32 === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.clz32 === "function"; }
§Math.imul ? function(){ return typeof Math.imul === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.imul === "function"; }
§Math.sign ? function(){ return typeof Math.sign === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.sign === "function"; }
§Math.log10 ? function(){ return typeof Math.log10 === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.log10 === "function"; }
§Math.log2 ? function(){ return typeof Math.log2 === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.log2 === "function"; }
§Math.log1p ? function(){ return typeof Math.log1p === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.log1p === "function"; }
§Math.expm1 ? function(){ return typeof Math.expm1 === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.expm1 === "function"; }
§Math.cosh ? function(){ return typeof Math.cosh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.cosh === "function"; }
§Math.sinh ? function(){ return typeof Math.sinh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.sinh === "function"; }
§Math.tanh ? function(){ return typeof Math.tanh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.tanh === "function"; }
§Math.acosh ? function(){ return typeof Math.acosh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.acosh === "function"; }
§Math.asinh ? function(){ return typeof Math.asinh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.asinh === "function"; }
§Math.atanh ? function(){ return typeof Math.atanh === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.atanh === "function"; }
§Math.trunc ? function(){ return typeof Math.trunc === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.trunc === "function"; }
§Math.fround ? function(){ return typeof Math.fround === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.fround === "function"; }
§Math.cbrt ? function(){ return typeof Math.cbrt === "function"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return typeof Math.cbrt === "function"; }
§Math.hypot ? function(){ return Math.hypot() === 0 && Math.hypot(1) === 1 && Math.hypot(9, 12, 20) === 25 && Math.hypot(27, 36, 60, 100) === 125; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error
	function(){ return Math.hypot() === 0 && Math.hypot(1) === 1 && Math.hypot(9, 12, 20) === 25 && Math.hypot(27, 36, 60, 100) === 125; }

§Date.prototype[Symbol.toPrimitive] ? function(){ var tp = Date.prototype[Symbol.toPrimitive];return tp.call(Object(2), "number") === 2 && tp.call(Object(2), "string") === "2" && tp.call(Object(2), "default") === "2"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ var tp = Date.prototype[Symbol.toPrimitive];return tp.call(Object(2), "number") === 2 && tp.call(Object(2), "string") === "2" && tp.call(Object(2), "default") === "2"; }

Array is subclassable
§length property (accessing) ? function(){ class C extends Array {}var c = new C();var len1 = c.length;c[2] = 'foo';var len2 = c.length;return len1 === 0 && len2 === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();var len1 = c.length;c[2] = 'foo';var len2 = c.length;return len1 === 0 && len2 === 3; }
§length property (setting) ? function(){ class C extends Array {}var c = new C();c[2] = 'foo';c.length = 1;return c.length === 1 && !(2 in c); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();c[2] = 'foo';c.length = 1;return c.length === 1 && !(2 in c); }
§correct prototype chain ? function(){ class C extends Array {}var c = new C();return c instanceof C && c instanceof Array && Object.getPrototypeOf(C) === Array; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();return c instanceof C && c instanceof Array && Object.getPrototypeOf(C) === Array; }
§Array.isArray support ? function(){ class C extends Array {}return Array.isArray(new C()); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}return Array.isArray(new C()); }
§Array.prototype.concat ? function(){ class C extends Array {}var c = new C();return c.concat(1) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();return c.concat(1) instanceof C; }
§Array.prototype.filter ? function(){ class C extends Array {}var c = new C();return c.filter(Boolean) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();return c.filter(Boolean) instanceof C; }
§Array.prototype.map ? function(){ class C extends Array {}var c = new C();return c.map(Boolean) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();return c.map(Boolean) instanceof C; }
§Array.prototype.slice ? function(){ class C extends Array {}var c = new C();c.push(2,4,6);return c.slice(1,2) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();c.push(2,4,6);return c.slice(1,2) instanceof C; }
§Array.prototype.splice ? function(){ class C extends Array {}var c = new C();c.push(2,4,6);return c.splice(1,2) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Array {}var c = new C();c.push(2,4,6);return c.splice(1,2) instanceof C; }
§Array.from ? function(){ class C extends Array {}return C.from({ length: 0 }) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}return C.from({ length: 0 }) instanceof C; }
§Array.of ? function(){ class C extends Array {}return C.of(0) instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Array {}return C.of(0) instanceof C; }
RegExp is subclassable
§basic functionality ? function(){ class R extends RegExp {}var r = new R("baz","g");return r.global && r.source === "baz"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class R extends RegExp {}var r = new R("baz","g");return r.global && r.source === "baz"; }
§correct prototype chain ? function(){ class R extends RegExp {}var r = new R("baz","g");return r instanceof R && r instanceof RegExp && Object.getPrototypeOf(R) === RegExp; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class R extends RegExp {}var r = new R("baz","g");return r instanceof R && r instanceof RegExp && Object.getPrototypeOf(R) === RegExp; }
§RegExp.prototype.exec ? function(){ class R extends RegExp {}var r = new R("baz","g");return r.exec("foobarbaz")[0] === "baz" && r.lastIndex === 9; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class R extends RegExp {}var r = new R("baz","g");return r.exec("foobarbaz")[0] === "baz" && r.lastIndex === 9; }
§RegExp.prototype.test ? function(){ class R extends RegExp {}var r = new R("baz");return r.test("foobarbaz"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class R extends RegExp {}var r = new R("baz");return r.test("foobarbaz"); }
Function is subclassable
§can be called ? function(){ class C extends Function {}var c = new C("return 'foo';");return c() === 'foo'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("return 'foo';");return c() === 'foo'; }
§correct prototype chain ? function(){ class C extends Function {}var c = new C("return 'foo';");return c instanceof C && c instanceof Function && Object.getPrototypeOf(C) === Function; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("return 'foo';");return c instanceof C && c instanceof Function && Object.getPrototypeOf(C) === Function; }
§can be used with "new" ? function(){ class C extends Function {}var c = new C("this.bar = 2;");c.prototype.baz = 3;return new c().bar === 2 && new c().baz === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("this.bar = 2;");c.prototype.baz = 3;return new c().bar === 2 && new c().baz === 3; }
§Function.prototype.call ? function(){ class C extends Function {}var c = new C("x", "return this.bar + x;");return c.call({bar:1}, 2) === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("x", "return this.bar + x;");return c.call({bar:1}, 2) === 3; }
§Function.prototype.apply ? function(){ class C extends Function {}var c = new C("x", "return this.bar + x;");return c.apply({bar:1}, [2]) === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("x", "return this.bar + x;");return c.apply({bar:1}, [2]) === 3; }
§Function.prototype.bind ? function(){ class C extends Function {}var c = new C("x", "y", "return this.bar + x + y;").bind({bar:1}, 2);return c(6) === 9 && c instanceof C; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error	Error Error	Error Error
	function(){ class C extends Function {}var c = new C("x", "y", "return this.bar + x + y;").bind({bar:1}, 2);return c(6) === 9 && c instanceof C; }
Promise is subclassable
§basic functionality ? function(){ class P extends Promise {}var p1 = new P(function(resolve, reject) { resolve("foo"); });var p2 = new P(function(resolve, reject) { reject("quux"); });var score = +(p1 instanceof P);function thenFn(result) { score += (result === "foo"); check(); }function catchFn(result) { score += (result === "quux"); check(); }function shouldNotRun(result) { score = -Infinity; }p1.then(thenFn, shouldNotRun);p2.then(shouldNotRun, catchFn);p1.catch(shouldNotRun);p2.catch(catchFn);p1.then(function() { // P.prototype.then() should return a new P score += p1.then() instanceof P && p1.then() !== p1; check();});function check() { if (score === 5) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class P extends Promise {}var p1 = new P(function(resolve, reject) { resolve("foo"); });var p2 = new P(function(resolve, reject) { reject("quux"); });var score = +(p1 instanceof P);function thenFn(result) { score += (result === "foo"); check(); }function catchFn(result) { score += (result === "quux"); check(); }function shouldNotRun(result) { score = -Infinity; }p1.then(thenFn, shouldNotRun);p2.then(shouldNotRun, catchFn);p1.catch(shouldNotRun);p2.catch(catchFn);p1.then(function() { // P.prototype.then() should return a new P score += p1.then() instanceof P && p1.then() !== p1; check();});function check() { if (score === 5) asyncTestPassed();} }
§correct prototype chain ? function(){ class C extends Promise {}var c = new C(function(resolve, reject) { resolve("foo"); });return c instanceof C && c instanceof Promise && Object.getPrototypeOf(C) === Promise; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Promise {}var c = new C(function(resolve, reject) { resolve("foo"); });return c instanceof C && c instanceof Promise && Object.getPrototypeOf(C) === Promise; }
§Promise.all ? function(){ class P extends Promise {}var fulfills = P.all([ new Promise(function(resolve) { setTimeout(resolve,2000,"foo"); }), new Promise(function(resolve) { setTimeout(resolve,1000,"bar"); })]);var rejects = P.all([ new Promise(function(_, reject) { setTimeout(reject, 2000,"baz"); }), new Promise(function(_, reject) { setTimeout(reject, 1000,"qux"); })]);var score = +(fulfills instanceof P);fulfills.then(function(result) { score += (result + "" === "foo,bar"); check(); });rejects.catch(function(result) { score += (result === "qux"); check(); });function check() { if (score === 3) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class P extends Promise {}var fulfills = P.all([ new Promise(function(resolve) { setTimeout(resolve,2000,"foo"); }), new Promise(function(resolve) { setTimeout(resolve,1000,"bar"); })]);var rejects = P.all([ new Promise(function(_, reject) { setTimeout(reject, 2000,"baz"); }), new Promise(function(_, reject) { setTimeout(reject, 1000,"qux"); })]);var score = +(fulfills instanceof P);fulfills.then(function(result) { score += (result + "" === "foo,bar"); check(); });rejects.catch(function(result) { score += (result === "qux"); check(); });function check() { if (score === 3) asyncTestPassed();} }
§Promise.race ? function(){ class P extends Promise {}var fulfills = P.race([ new Promise(function(resolve) { setTimeout(resolve,1000,"foo"); }), new Promise(function(_, reject) { setTimeout(reject, 2000,"bar"); })]);var rejects = P.race([ new Promise(function(_, reject) { setTimeout(reject, 1000,"baz"); }), new Promise(function(resolve) { setTimeout(resolve,2000,"qux"); })]);var score = +(fulfills instanceof P);fulfills.then(function(result) { score += (result === "foo"); check(); });rejects.catch(function(result) { score += (result === "baz"); check(); });function check() { if (score === 3) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class P extends Promise {}var fulfills = P.race([ new Promise(function(resolve) { setTimeout(resolve,1000,"foo"); }), new Promise(function(_, reject) { setTimeout(reject, 2000,"bar"); })]);var rejects = P.race([ new Promise(function(_, reject) { setTimeout(reject, 1000,"baz"); }), new Promise(function(resolve) { setTimeout(resolve,2000,"qux"); })]);var score = +(fulfills instanceof P);fulfills.then(function(result) { score += (result === "foo"); check(); });rejects.catch(function(result) { score += (result === "baz"); check(); });function check() { if (score === 3) asyncTestPassed();} }
miscellaneous subclassables
§Boolean is subclassable ? function(){ class C extends Boolean {}var c = new C(true);return c instanceof Boolean && c instanceof C && c == true; // eslint-disable-line eqeqeq }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Boolean {}var c = new C(true);return c instanceof Boolean && c instanceof C && c == true; // eslint-disable-line eqeqeq }
§Number is subclassable ? function(){ class C extends Number {}var c = new C(6);return c instanceof Number && c instanceof C && +c === 6; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Number {}var c = new C(6);return c instanceof Number && c instanceof C && +c === 6; }
§String is subclassable ? function(){ class C extends String {}var c = new C("golly");return c instanceof String && c instanceof C && c + '' === "golly" && c[0] === "g" && c.length === 5; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error Error	Error Error	Error Error
	function(){ class C extends String {}var c = new C("golly");return c instanceof String && c instanceof C && c + '' === "golly" && c[0] === "g" && c.length === 5; }
§Error is subclassable ? function(){ class C extends Error {}var c = new C();return c instanceof Error && c instanceof C && Object.prototype.toString.call(c) === "[object Error]"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ class C extends Error {}var c = new C();return c instanceof Error && c instanceof C && Object.prototype.toString.call(c) === "[object Error]"; }
§Map is subclassable ? function(){ var key = {};class M extends Map {}var map = new M();map.set(key, 123);return map instanceof M && map.has(key) && map.get(key) === 123; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var key = {};class M extends Map {}var map = new M();map.set(key, 123);return map instanceof M && map.has(key) && map.get(key) === 123; }
§Set is subclassable ? function(){ var obj = {};class S extends Set {}var set = new S();set.add(123);set.add(123);return set instanceof S && set.has(123); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var obj = {};class S extends Set {}var set = new S();set.add(123);set.add(123);return set instanceof S && set.has(123); }

non-strict function semantics
§hoisted block-level function declaration ? function(){ // Note: only available outside of strict mode.if (!this) return false;var passed = f() === 1;function f() { return 1; }passed &= typeof g === 'undefined';{ function g() { return 1; } }passed &= g() === 1;passed &= h() === 2;{ function h() { return 1; } }function h() { return 2; }passed &= h() === 1;return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No
	function(){ // Note: only available outside of strict mode.if (!this) return false;var passed = f() === 1;function f() { return 1; }passed &= typeof g === 'undefined';{ function g() { return 1; } }passed &= g() === 1;passed &= h() === 2;{ function h() { return 1; } }function h() { return 2; }passed &= h() === 1;return passed; }
§labeled function statements ? function(){ // Note: only available outside of strict mode.if (!this) return false;label: function foo() { return 2; }return foo() === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ // Note: only available outside of strict mode.if (!this) return false;label: function foo() { return 2; }return foo() === 2; }
§function statements in if-statement clauses ? function(){ // Note: only available outside of strict mode.if (!this) return false;if(true) function foo() { return 2; }if(false) {} else function bar() { return 3; }if(true) function baz() { return 4; } else {}if(false) function qux() { return 5; } else function qux() { return 6; }return foo() === 2 && bar() === 3 && baz() === 4 && qux() === 6; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ // Note: only available outside of strict mode.if (!this) return false;if(true) function foo() { return 2; }if(false) {} else function bar() { return 3; }if(true) function baz() { return 4; } else {}if(false) function qux() { return 5; } else function qux() { return 6; }return foo() === 2 && bar() === 3 && baz() === 4 && qux() === 6; }
__proto__ in object literals
§basic support ? function(){ return { __proto__ : [] } instanceof Array && !({ __proto__ : null } instanceof Object); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return { __proto__ : [] } instanceof Array && !({ __proto__ : null } instanceof Object); }
§multiple __proto__ is an error ? function(){ try { eval("({ __proto__ : [], __proto__: {} })");}catch(e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No
	function(){ try { eval("({ __proto__ : [], __proto__: {} })");}catch(e) { return true;} }
§not a computed property ? function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}var a = "__proto__";return !({ [a] : [] } instanceof Array); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}var a = "__proto__";return !({ [a] : [] } instanceof Array); }
§not a shorthand property ? function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}var __proto__ = [];return !({ __proto__ } instanceof Array); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}var __proto__ = [];return !({ __proto__ } instanceof Array); }
§not a shorthand method ? function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}return !({ __proto__(){} } instanceof Function); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error
	function(){ if (!({ __proto__ : [] } instanceof Array)) { return false;}return !({ __proto__(){} } instanceof Function); }
Object.prototype.__proto__
§get prototype ? function(){ var A = function(){};return (new A()).__proto__ === A.prototype; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var A = function(){};return (new A()).__proto__ === A.prototype; }
§set prototype ? function(){ var o = {};o.__proto__ = Array.prototype;return o instanceof Array; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var o = {};o.__proto__ = Array.prototype;return o instanceof Array; }
§absent from Object.create(null) ? function(){ var o = Object.create(null), p = {};o.__proto__ = p;return Object.getPrototypeOf(o) !== p; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ var o = Object.create(null), p = {};o.__proto__ = p;return Object.getPrototypeOf(o) !== p; }
§present in hasOwnProperty() ? function(){ return Object.prototype.hasOwnProperty('__proto__'); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return Object.prototype.hasOwnProperty('__proto__'); }
§correct property descriptor ? function(){ var desc = Object.getOwnPropertyDescriptor(Object.prototype,"__proto__");var A = function(){};return (desc && "get" in desc && "set" in desc && desc.configurable && !desc.enumerable); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ var desc = Object.getOwnPropertyDescriptor(Object.prototype,"__proto__");var A = function(){};return (desc && "get" in desc && "set" in desc && desc.configurable && !desc.enumerable); }
§present in Object.getOwnPropertyNames() ? function(){ return Object.getOwnPropertyNames(Object.prototype).indexOf('__proto__') > -1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No
	function(){ return Object.getOwnPropertyNames(Object.prototype).indexOf('__proto__') > -1; }
String.prototype HTML methods
§existence ? function(){ var i, names = ["anchor", "big", "bold", "fixed", "fontcolor", "fontsize", "italics", "link", "small", "strike", "sub", "sup"];for (i = 0; i < names.length; i++) { if (typeof String.prototype[names[i]] !== 'function') { return false; }}return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var i, names = ["anchor", "big", "bold", "fixed", "fontcolor", "fontsize", "italics", "link", "small", "strike", "sub", "sup"];for (i = 0; i < names.length; i++) { if (typeof String.prototype[names[i]] !== 'function') { return false; }}return true; }
§tags' names are lowercase ? function(){ var i, names = ["anchor", "big", "bold", "fixed", "fontcolor", "fontsize", "italics", "link", "small", "strike", "sub", "sup"];for (i = 0; i < names.length; i++) { if (""[names[i]]().toLowerCase() !== ""[names[i]]()) { return false; }}return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var i, names = ["anchor", "big", "bold", "fixed", "fontcolor", "fontsize", "italics", "link", "small", "strike", "sub", "sup"];for (i = 0; i < names.length; i++) { if (""[names[i]]().toLowerCase() !== ""[names[i]]()) { return false; }}return true; }
§quotes in arguments are escaped ? function(){ var i, names = ["anchor", "fontcolor", "fontsize", "link"];for (i = 0; i < names.length; i++) { if (""[names[i]]('"') !== ""[names[i]]('&' + 'quot;')) { return false; }}return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var i, names = ["anchor", "fontcolor", "fontsize", "link"];for (i = 0; i < names.length; i++) { if (""[names[i]]('"') !== ""[names[i]]('&' + 'quot;')) { return false; }}return true; }
RegExp.prototype.compile
§basic functionality ? function(){ if (typeof RegExp.prototype.compile !== 'function') return falsevar rx = /a/;rx.compile('b');return rx.test('b'); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ if (typeof RegExp.prototype.compile !== 'function') return falsevar rx = /a/;rx.compile('b');return rx.test('b'); }
§returns this ? function(){ var rx = /a/;return rx.compile('b') === rx; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ var rx = /a/;return rx.compile('b') === rx; }
RegExp syntax extensions
§hyphens in character sets ? function(){ return /[\w-_]/.exec("-")[0] === "-"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /[\w-_]/.exec("-")[0] === "-"; }
§invalid character escapes ? function(){ return /\z/.exec("\\z")[0] === "z" && /[\z]/.exec("[\\z]")[0] === "z"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\z/.exec("\\z")[0] === "z" && /[\z]/.exec("[\\z]")[0] === "z"; }
§invalid control-character escapes ? function(){ return /\c2/.exec("\\c2")[0] === "\\c2"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\c2/.exec("\\c2")[0] === "\\c2"; }
§invalid Unicode escapes ? function(){ return /\u1/.exec("u1")[0] === "u1" && /[\u1]/.exec("u")[0] === "u"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\u1/.exec("u1")[0] === "u1" && /[\u1]/.exec("u")[0] === "u"; }
§invalid hexadecimal escapes ? function(){ return /\x1/.exec("x1")[0] === "x1" && /[\x1]/.exec("x")[0] === "x"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\x1/.exec("x1")[0] === "x1" && /[\x1]/.exec("x")[0] === "x"; }
§incomplete patterns and quantifiers ? function(){ return /x{1/.exec("x{1")[0] === "x{1" && /x]1/.exec("x]1")[0] === "x]1"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /x{1/.exec("x{1")[0] === "x{1" && /x]1/.exec("x]1")[0] === "x]1"; }
§octal escape sequences ? function(){ return /\041/.exec("!")[0] === "!" && /[\041]/.exec("!")[0] === "!"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\041/.exec("!")[0] === "!" && /[\041]/.exec("!")[0] === "!"; }
§invalid backreferences become octal escapes ? function(){ return /\41/.exec("!")[0] === "!" && /[\41]/.exec("!")[0] === "!"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return /\41/.exec("!")[0] === "!" && /[\41]/.exec("!")[0] === "!"; }

§HTML-style comments ? function(){ --> A comment<!-- Another commentvar a = 3; <!-- Another commentreturn a === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ --> A comment<!-- Another commentvar a = 3; <!-- Another commentreturn a === 3; }

exponentiation (**) operator
§basic support ? function(){ return 2 3 === 8 && -(5 2) === -25 && (-5) ** 2 === 25; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return 2 3 === 8 && -(5 2) === -25 && (-5) ** 2 === 25; }
§assignment ? function(){ var a = 2; a **= 3; return a === 8; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var a = 2; a **= 3; return a === 8; }
§early syntax error for unary negation without parens ? function(){ if (2 3 !== 8) { return false;}try { Function("-5 2")();} catch (e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ if (2 3 !== 8) { return false;}try { Function("-5 2")();} catch (e) { return true;} }
Array.prototype.includes
§Array.prototype.includes ? function(){ return [1, 2, 3].includes(1) && ![1, 2, 3].includes(4) && ![1, 2, 3].includes(1, 1) && [NaN].includes(NaN); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return [1, 2, 3].includes(1) && ![1, 2, 3].includes(4) && ![1, 2, 3].includes(1, 1) && [NaN].includes(NaN); }
§Array.prototype.includes handles sparse arrays ? function(){ return [,].includes() && Array(1).includes(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return [,].includes() && Array(1).includes(); }
§Array.prototype.includes is generic ? function(){ var passed = 0;return [].includes.call( { get "0"() { passed = NaN; return 'foo'; }, get "11"() { passed += 1; return 0; }, get "19"() { passed += 1; return 'foo'; }, get "21"() { passed = NaN; return 'foo'; }, get length() { passed += 1; return 24; } }, 'foo', 6) === true && passed === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var passed = 0;return [].includes.call( { get "0"() { passed = NaN; return 'foo'; }, get "11"() { passed += 1; return 0; }, get "19"() { passed += 1; return 'foo'; }, get "21"() { passed = NaN; return 'foo'; }, get length() { passed += 1; return 24; } }, 'foo', 6) === true && passed === 3; }
§%TypedArray%.prototype.includes ? function(){ return [ Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, Float32Array, Float64Array].every(function (TypedArray) { return new TypedArray([1, 2, 3]).includes(1) && !new TypedArray([1, 2, 3]).includes(4) && !new TypedArray([1, 2, 3]).includes(1, 1);}); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ return [ Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, Float32Array, Float64Array].every(function (TypedArray) { return new TypedArray([1, 2, 3]).includes(1) && !new TypedArray([1, 2, 3]).includes(4) && !new TypedArray([1, 2, 3]).includes(1, 1);}); }


§generator functions can't be used with "new" ? function(){ function * generator() { yield 3;}try { new generator();} catch (e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Error No	Error Error
	function(){ function * generator() { yield 3;}try { new generator();} catch (e) { return true;} }
§generator throw() caught by inner generator ? function(){ function * generator() { yield * (function * () { try { yield 'foo'; } catch (e) { return; } }()); yield 'bar';}var iter = generator();iter.next();return iter['throw']().value === 'bar'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ function * generator() { yield * (function * () { try { yield 'foo'; } catch (e) { return; } }()); yield 'bar';}var iter = generator();iter.next();return iter['throw']().value === 'bar'; }
§strict fn w/ non-strict non-simple params is error ? function(){ function foo(...a) {} try { Function("function bar(...a) {'use strict';}")(); } catch (e) { return true; } }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error No	Error No	Error Error	Error Error
	function(){ function foo(...a) {} try { Function("function bar(...a) {'use strict';}")(); } catch (e) { return true; } }
§nested rest destructuring, declarations ? function(){ var [x, ...[y, ...z]] = [1,2,3,4];return x === 1 && y === 2 && z + '' === '3,4'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ var [x, ...[y, ...z]] = [1,2,3,4];return x === 1 && y === 2 && z + '' === '3,4'; }
§nested rest destructuring, parameters ? function(){ return function ([x, ...[y, ...z]]) { return x === 1 && y === 2 && z + '' === '3,4';}([1,2,3,4]); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ return function ([x, ...[y, ...z]]) { return x === 1 && y === 2 && z + '' === '3,4';}([1,2,3,4]); }
§Proxy, "enumerate" handler removed ? function(){ var passed = true;var proxy = new Proxy({}, { enumerate: function () { passed = false; }});for (var key in proxy); // Should not throw, nor execute the 'enumerate' method.return passed; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ var passed = true;var proxy = new Proxy({}, { enumerate: function () { passed = false; }});for (var key in proxy); // Should not throw, nor execute the 'enumerate' method.return passed; }
§Proxy internal calls, Array.prototype.includes ? function(){ // Array.prototype.includes -> Get -> [[Get]]var get = [];var p = new Proxy({length: 3, 0: '', 1: '', 2: '', 3: ''}, { get: function (o, k) { get.push(k); return o[k]; }});Array.prototype.includes.call(p, {});if (get + '' !== "length,0,1,2") return;get = [];p = new Proxy({length: 4, 0: NaN, 1: '', 2: NaN, 3: ''}, { get: function (o, k) { get.push(k); return o[k]; }});Array.prototype.includes.call(p, NaN, 1);return (get + '' === "length,1,2"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error
	function(){ // Array.prototype.includes -> Get -> [[Get]]var get = [];var p = new Proxy({length: 3, 0: '', 1: '', 2: '', 3: ''}, { get: function (o, k) { get.push(k); return o[k]; }});Array.prototype.includes.call(p, {});if (get + '' !== "length,0,1,2") return;get = [];p = new Proxy({length: 4, 0: NaN, 1: '', 2: NaN, 3: ''}, { get: function (o, k) { get.push(k); return o[k]; }});Array.prototype.includes.call(p, NaN, 1);return (get + '' === "length,1,2"); }


§RegExp "u" flag, case folding ? function(){ return "ſ".match(/\w/iu) && !"ſ".match(/\W/iu) && "\u212a".match(/\w/iu) && !"\u212a".match(/\W/iu) && "\u212a".match(/.\b/iu) && "ſ".match(/.\b/iu) && !"\u212a".match(/.\B/iu) && !"ſ".match(/.\B/iu); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	Error Error	Error Error	Error Error	Error Error
	function(){ return "ſ".match(/\w/iu) && !"ſ".match(/\W/iu) && "\u212a".match(/\w/iu) && !"\u212a".match(/\W/iu) && "\u212a".match(/.\b/iu) && "ſ".match(/.\b/iu) && !"\u212a".match(/.\B/iu) && !"ſ".match(/.\B/iu); }
§arguments.caller removed ? function(){ return (function () { 'use strict'; return !Object.getOwnPropertyDescriptor(arguments, 'caller');})(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ return (function () { 'use strict'; return !Object.getOwnPropertyDescriptor(arguments, 'caller');})(); }

object rest/spread properties
§object rest properties ? function(){ var { a, ...rest } = { a: 1, b: 2, c: 3 };return a === 1 && rest.a === void undefined && rest.b === 2 && rest.c === 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var { a, ...rest } = { a: 1, b: 2, c: 3 };return a === 1 && rest.a === void undefined && rest.b === 2 && rest.c === 3; }
§object spread properties ? function(){ var spread = { b: 2, c: 3 };var O = { a: 1, ...spread };return O !== spread && (O.a + O.b + O.c) === 6; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var spread = { b: 2, c: 3 };var O = { a: 1, ...spread };return O !== spread && (O.a + O.b + O.c) === 6; }
Promise.prototype.finally
§basic support ? function(){ var p1 = Promise.resolve("foo");var p2 = Promise.reject("bar");var score = 0;function thenFn(result) { score += (result === "foo"); check();}function catchFn(result) { score += (result === "bar"); check();}function finallyFn() { score += (arguments.length === 0); check();}p1.then(thenFn);p1.finally(finallyFn);p1.finally(function () { // should return a new Promise score += p1.finally() !== p1; check();});p2.catch (catchFn);p2.finally(finallyFn);function check() { if (score === 5) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var p1 = Promise.resolve("foo");var p2 = Promise.reject("bar");var score = 0;function thenFn(result) { score += (result === "foo"); check();}function catchFn(result) { score += (result === "bar"); check();}function finallyFn() { score += (arguments.length === 0); check();}p1.then(thenFn);p1.finally(finallyFn);p1.finally(function () { // should return a new Promise score += p1.finally() !== p1; check();});p2.catch (catchFn);p2.finally(finallyFn);function check() { if (score === 5) asyncTestPassed();} }
§don't change resolution value ? function(){ var score = 0;function thenFn(result) { score += (result === "foo"); check();}function catchFn(result) { score += (result === "bar"); check();}function finallyFn() { score++; check(); return Promise.resolve("foobar");}Promise.resolve("foo").finally(finallyFn).then(thenFn);Promise.reject("bar").finally(finallyFn).catch(catchFn);function check() { if (score === 4) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var score = 0;function thenFn(result) { score += (result === "foo"); check();}function catchFn(result) { score += (result === "bar"); check();}function finallyFn() { score++; check(); return Promise.resolve("foobar");}Promise.resolve("foo").finally(finallyFn).then(thenFn);Promise.reject("bar").finally(finallyFn).catch(catchFn);function check() { if (score === 4) asyncTestPassed();} }
§change rejection value ? function(){ var score = 0;Promise .reject("foobar") .finally(function () { return Promise.reject("foo"); }) .catch (function (result) { score += (result === "foo"); check(); return Promise.reject("foobar"); }) .finally(function () { throw new Error('bar'); }) .catch (function (result) { score += (result.message === "bar"); check(); });function check() { if (score === 2) asyncTestPassed();} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var score = 0;Promise .reject("foobar") .finally(function () { return Promise.reject("foo"); }) .catch (function (result) { score += (result === "foo"); check(); return Promise.reject("foobar"); }) .finally(function () { throw new Error('bar'); }) .catch (function (result) { score += (result.message === "bar"); check(); });function check() { if (score === 2) asyncTestPassed();} }

§s (dotAll) flag for regular expressions ? function(){ const regex = /foo.bar/s;return regex.test('foo\nbar'); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const regex = /foo.bar/s;return regex.test('foo\nbar'); }
§RegExp named capture groups ? function(){ var result = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/.exec('2016-03-11');return result.groups.year === '2016' && result.groups.month === '03' && result.groups.day === '11' && result[0] === '2016-03-11' && result[1] === '2016' && result[2] === '03' && result[3] === '11'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var result = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/.exec('2016-03-11');return result.groups.year === '2016' && result.groups.month === '03' && result.groups.day === '11' && result[0] === '2016-03-11' && result[1] === '2016' && result[2] === '03' && result[3] === '11'; }
§RegExp Lookbehind Assertions ? function(){ return /(?<=a)b/.test('ab') && /(?<!a)b/.test('cb') && !/(?<=a)b/.test('b'); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error
	function(){ return /(?<=a)b/.test('ab') && /(?<!a)b/.test('cb') && !/(?<=a)b/.test('b'); }
RegExp Unicode Property Escapes
§basic ? function(){ const regexGreekSymbol = /\p{Script=Greek}/u;return regexGreekSymbol.test('π'); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const regexGreekSymbol = /\p{Script=Greek}/u;return regexGreekSymbol.test('π'); }
§Unicode 11 ? function(){ return /\p{Extended_Pictographic}/u.test("\xA9") && /\p{Emoji}/u.test("🥰"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Extended_Pictographic}/u.test("\xA9") && /\p{Emoji}/u.test("🥰"); }
§Unicode 12 ? function(){ return /\p{Script=Elymaic}/u.test("\u{10fe0}") && /\p{Emoji}/u.test("🥱"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Elymaic}/u.test("\u{10fe0}") && /\p{Emoji}/u.test("🥱"); }
§Unicode 12.1 ? function(){ return /\p{Other_Symbol}/u.test("\u32FF"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	Yes Yes	No No	No No	No No	No No	Error No	Error No	Error No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Other_Symbol}/u.test("\u32FF"); }
§Unicode 13 ? function(){ return /\p{Script=Chorasmian}/u.test("\u{10fb0}") && /\p{Emoji}/u.test("🥲"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Chorasmian}/u.test("\u{10fb0}") && /\p{Emoji}/u.test("🥲"); }
§Unicode 14 ? function(){ return /\p{Script=Vithkuqi}/u.test("\u{10570}") && /\p{Emoji}/u.test("🫠"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Vithkuqi}/u.test("\u{10570}") && /\p{Emoji}/u.test("🫠"); }
§Unicode 15 ? function(){ return /\p{Script=Kawi}/u.test("\u{11f00}") && /\p{Emoji}/u.test("🫨"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Kawi}/u.test("\u{11f00}") && /\p{Emoji}/u.test("🫨"); }
§Unicode 15.1 ? function(){ return /\p{Unified_Ideograph}/u.test("\u{2ebf0}"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	Yes Yes	Yes Yes	No No	No No	No No	No No	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error No	Error No	Error No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Unified_Ideograph}/u.test("\u{2ebf0}"); }
§Unicode 16.0 ? function(){ return /\p{Script=Todhri}/u.test("\u{105c0}") && /\p{Emoji}/u.test("🫩"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Yes Yes	Error Error	Error Error	Error Error	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Todhri}/u.test("\u{105c0}") && /\p{Emoji}/u.test("🫩"); }
§Unicode 17.0 ? function(){ return /\p{Script=Sidetic}/u.test("\u{10940}") && /\p{Emoji}/u.test("🫍"); }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /\p{Script=Sidetic}/u.test("\u{10940}") && /\p{Emoji}/u.test("🫍"); }
Asynchronous Iterators
§async generators ? function(){ async function*generator() { yield 42;}var iterator = generator();iterator.next().then(function (step) { if(iterator[Symbol.asyncIterator]() === iterator && step.done === false && step.value === 42)asyncTestPassed();}); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ async function*generator() { yield 42;}var iterator = generator();iterator.next().then(function (step) { if(iterator[Symbol.asyncIterator]() === iterator && step.done === false && step.value === 42)asyncTestPassed();}); }
§for-await-of loops ? function(){ var asyncIterable = {};asyncIterable[Symbol.asyncIterator] = function () { var i = 0; return { next: function () { switch(++i) { case 1: return Promise.resolve({done: false, value: 'a'}); case 2: return Promise.resolve({done: false, value: 'b'}); } return Promise.resolve({done: true}); } };};(async function () { var result = ''; for await(var value of asyncIterable)result += value; if(result === 'ab')asyncTestPassed();})(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var asyncIterable = {};asyncIterable[Symbol.asyncIterator] = function () { var i = 0; return { next: function () { switch(++i) { case 1: return Promise.resolve({done: false, value: 'a'}); case 2: return Promise.resolve({done: false, value: 'b'}); } return Promise.resolve({done: true}); } };};(async function () { var result = ''; for await(var value of asyncIterable)result += value; if(result === 'ab')asyncTestPassed();})(); }


§Proxy "ownKeys" handler, duplicate keys for non-extensible targets ? function(){ var p = new Proxy({}, { ownKeys() { return ["a", "a"]; }});try { Object.keys(p);} catch (e) { return e instanceof TypeError;}return false; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error	Error Error	Error Error	Error Error
	function(){ var p = new Proxy({}, { ownKeys() { return ["a", "a"]; }});try { Object.keys(p);} catch (e) { return e instanceof TypeError;}return false; }
§template literal revision ? function(){ function tag(strings, a) { return strings[0] === void undefined && strings.raw[0] === "\\01\\1\\xg\\xAg\\u0\\u0g\\u00g\\u000g\\u{g\\u{0\\u{110000}" && strings[1] === "\0" && strings.raw[1] === "\\0" && a === 0;}return tag`\01\1\xg\xAg\u0\u0g\u00g\u000g\u{g\u{0\u{110000}${0}\0`; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ function tag(strings, a) { return strings[0] === void undefined && strings.raw[0] === "\\01\\1\\xg\\xAg\\u0\\u0g\\u00g\\u000g\\u{g\\u{0\\u{110000}" && strings[1] === "\0" && strings.raw[1] === "\\0" && a === 0;}return tag`\01\1\xg\xAg\u0\u0g\u00g\u000g\u{g\u{0\u{110000}${0}\0`; }

Symbol.prototype.description
§basic ? function(){ return Symbol('foo').description === 'foo'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error
	function(){ return Symbol('foo').description === 'foo'; }
§empty description ? function(){ return Symbol('').description === ''; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error
	function(){ return Symbol('').description === ''; }
§undefined description ? function(){ return Symbol.prototype.hasOwnProperty('description') && Symbol().description === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error
	function(){ return Symbol.prototype.hasOwnProperty('description') && Symbol().description === void undefined; }

§Object.fromEntries ? function(){ var object = Object.fromEntries(new Map([['foo', 42], ['bar', 23]]));return object.foo === 42 && object.bar === 23; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var object = Object.fromEntries(new Map([['foo', 42], ['bar', 23]]));return object.foo === 42 && object.bar === 23; }
string trimming
§String.prototype.trimLeft ? function(){ return ' \t \n abc \t\n'.trimLeft() === 'abc \t\n'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return ' \t \n abc \t\n'.trimLeft() === 'abc \t\n'; }
§String.prototype.trimRight ? function(){ return ' \t \n abc \t\n'.trimRight() === ' \t \n abc'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ return ' \t \n abc \t\n'.trimRight() === ' \t \n abc'; }
§String.prototype.trimStart ? function(){ return ' \t \n abc \t\n'.trimStart() === 'abc \t\n'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return ' \t \n abc \t\n'.trimStart() === 'abc \t\n'; }
§String.prototype.trimEnd ? function(){ return ' \t \n abc \t\n'.trimEnd() === ' \t \n abc'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return ' \t \n abc \t\n'.trimEnd() === ' \t \n abc'; }
Array.prototype.{flat, flatMap}
§Array.prototype.flat ? function(){ return [1, [2, 3], [4, [5, 6]]].flat().join('') === '12345,6'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return [1, [2, 3], [4, [5, 6]]].flat().join('') === '12345,6'; }
§Array.prototype.flatMap ? function(){ return [{a: 1, b: 2}, {a: 3, b: 4}].flatMap(function (it) { return [it.a, it.b];}).join('') === '1234'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return [{a: 1, b: 2}, {a: 3, b: 4}].flatMap(function (it) { return [it.a, it.b];}).join('') === '1234'; }
§flat and flatMap in Array.prototype[@@unscopables] ? function(){ return Array.prototype[Symbol.unscopables].flat && Array.prototype[Symbol.unscopables].flatMap; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error
	function(){ return Array.prototype[Symbol.unscopables].flat && Array.prototype[Symbol.unscopables].flatMap; }

optional catch binding
§basic ? function(){ try { throw new Error();}catch { return true;}return false; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ try { throw new Error();}catch { return true;}return false; }
§await ? function(){ (async function () { try { await Promise.reject(); } catch { asyncTestPassed(); }})(); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ (async function () { try { await Promise.reject(); } catch { asyncTestPassed(); }})(); }
§yield ? function(){ function *foo() { try { yield; } catch { return true; }}var it = foo();it.next();return it.throw().value; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ function *foo() { try { yield; } catch { return true; }}var it = foo();it.next();return it.throw().value; }
Function.prototype.toString revision
§functions created with the Function constructor ? function(){ var fn = Function('a', ' /\x2A a \x2A/ b, c /\x2A b \x2A/ //', '/\x2A c \x2A/ ; /\x2A d \x2A/ //');var str = 'function anonymous(a, /\x2A a \x2A/ b, c /\x2A b \x2A/ //\n) {\n/\x2A c \x2A/ ; /\x2A d \x2A/ //\n}';return fn + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No Flag	No Flag	No No	No No	No No	No No	No No	No No	No No	No No	Error Error
	function(){ var fn = Function('a', ' /\x2A a \x2A/ b, c /\x2A b \x2A/ //', '/\x2A c \x2A/ ; /\x2A d \x2A/ //');var str = 'function anonymous(a, /\x2A a \x2A/ b, c /\x2A b \x2A/ //\n) {\n/\x2A c \x2A/ ; /\x2A d \x2A/ //\n}';return fn + '' === str; }
§arrows ? function(){ var str = 'a => b';return eval('(' + str + ')') + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error
	function(){ var str = 'a => b';return eval('(' + str + ')') + '' === str; }
§[native code] ? function(){ const NATIVE_EVAL_RE = /\bfunction\b[\s\S]\beval\b[\s\S]\([\s\S]\)[\s\S]\{[\s\S]\[[\s\S]\bnative\b[\s\S]+\bcode\b[\s\S]\][\s\S]\}/;return NATIVE_EVAL_RE.test(eval + ''); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ const NATIVE_EVAL_RE = /\bfunction\b[\s\S]\beval\b[\s\S]\([\s\S]\)[\s\S]\{[\s\S]\[[\s\S]\bnative\b[\s\S]+\bcode\b[\s\S]\][\s\S]\}/;return NATIVE_EVAL_RE.test(eval + ''); }
§class expression with implicit constructor ? function(){ var str = 'class A {}';return eval('(' + str + ')') + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var str = 'class A {}';return eval('(' + str + ')') + '' === str; }
§class expression with explicit constructor ? function(){ var str = 'class /\x2A a \x2A/ A /\x2A b \x2A/ extends /\x2A c \x2A/ function B() {} /\x2A d \x2A/ { /\x2A e \x2A/ constructor /\x2A f \x2A/ ( /\x2A g \x2A/ ) /\x2A h \x2A/ { /\x2A i \x2A/ ; /\x2A j \x2A/ } /\x2A k \x2A/ m /\x2A l \x2A/ ( /\x2A m \x2A/ ) /\x2A n \x2A/ { /\x2A o \x2A/ } /\x2A p \x2A/ }';return eval('(/\x2A before \x2A/' + str + '/\x2A after \x2A/)') + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error
	function(){ var str = 'class /\x2A a \x2A/ A /\x2A b \x2A/ extends /\x2A c \x2A/ function B() {} /\x2A d \x2A/ { /\x2A e \x2A/ constructor /\x2A f \x2A/ ( /\x2A g \x2A/ ) /\x2A h \x2A/ { /\x2A i \x2A/ ; /\x2A j \x2A/ } /\x2A k \x2A/ m /\x2A l \x2A/ ( /\x2A m \x2A/ ) /\x2A n \x2A/ { /\x2A o \x2A/ } /\x2A p \x2A/ }';return eval('(/\x2A before \x2A/' + str + '/\x2A after \x2A/)') + '' === str; }
§unicode escape sequences in identifiers ? function(){ var str = 'function \\u0061(\\u{62}, \\u0063) { \\u0062 = \\u{00063}; return b; }';return eval('(/\x2A before \x2A/' + str + '/\x2A after \x2A/)') + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No Flag	No Flag	No No	No No	No No	No No	No No	No No	No No	Error Error	Error Error
	function(){ var str = 'function \\u0061(\\u{62}, \\u0063) { \\u0062 = \\u{00063}; return b; }';return eval('(/\x2A before \x2A/' + str + '/\x2A after \x2A/)') + '' === str; }
§methods and computed property names ? function(){ var str = '[ /\x2A a \x2A/ "f" /\x2A b \x2A/ ] /\x2A c \x2A/ ( /\x2A d \x2A/ ) /\x2A e \x2A/ { /\x2A f \x2A/ }';return eval('({ /\x2A before \x2A/' + str + '/\x2A after \x2A/ }.f)') + '' === str; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No Flag	No Flag	No No	No No	No No	No No	No No	No No	No No	Error Error	Error Error
	function(){ var str = '[ /\x2A a \x2A/ "f" /\x2A b \x2A/ ] /\x2A c \x2A/ ( /\x2A d \x2A/ ) /\x2A e \x2A/ { /\x2A f \x2A/ }';return eval('({ /\x2A before \x2A/' + str + '/\x2A after \x2A/ }.f)') + '' === str; }
JSON superset
§LINE SEPARATOR can appear in string literals ? function(){ return eval("'\u2028'") === "\u2028"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return eval("'\u2028'") === "\u2028"; }
§PARAGRAPH SEPARATOR can appear in string literals ? function(){ return eval("'\u2029'") === "\u2029"; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return eval("'\u2029'") === "\u2029"; }

§Well-formed JSON.stringify ? function(){ return JSON.stringify('\uDF06\uD834') === "\"\\udf06\\ud834\"" && JSON.stringify('\uDEAD') === "\"\\udead\""; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ return JSON.stringify('\uDF06\uD834') === "\"\\udf06\\ud834\"" && JSON.stringify('\uDEAD') === "\"\\udead\""; }

String.prototype.matchAll
§basic functionality ? function(){ var iterator = '11a2bb'.matchAll(/(\d)(\D)/g);if(iterator[Symbol.iterator]() !== iterator)return false;var a = '', b = '', c = '', step;while(!(step = iterator.next()).done) { a += step.value[0]; b += step.value[1]; c += step.value[2];}return a === '1a2b' && b === '12' && c === 'ab'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var iterator = '11a2bb'.matchAll(/(\d)(\D)/g);if(iterator[Symbol.iterator]() !== iterator)return false;var a = '', b = '', c = '', step;while(!(step = iterator.next()).done) { a += step.value[0]; b += step.value[1]; c += step.value[2];}return a === '1a2b' && b === '12' && c === 'ab'; }
§throws on non-global regex ? function(){ if (typeof String.prototype.matchAll !== 'function') return false;try { '11a2bb'.matchAll(/(\d)(\D)/);} catch (e) { return true;} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ if (typeof String.prototype.matchAll !== 'function') return false;try { '11a2bb'.matchAll(/(\d)(\D)/);} catch (e) { return true;} }
BigInt
§basic functionality ? function(){ return (1n + 2n) === 3n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return (1n + 2n) === 3n; }
§constructor ? function(){ return BigInt("3") === 3n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return BigInt("3") === 3n; }
§BigInt.asUintN ? function(){ return typeof BigInt.asUintN === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return typeof BigInt.asUintN === 'function'; }
§BigInt.asIntN ? function(){ return typeof BigInt.asIntN === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return typeof BigInt.asIntN === 'function'; }
§BigInt64Array ? function(){ var buffer = new ArrayBuffer(64);var view = new BigInt64Array(buffer);view[0] = 0x8000000000000000n;return view[0] === -0x8000000000000000n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var buffer = new ArrayBuffer(64);var view = new BigInt64Array(buffer);view[0] = 0x8000000000000000n;return view[0] === -0x8000000000000000n; }
§BigUint64Array ? function(){ var buffer = new ArrayBuffer(64);var view = new BigUint64Array(buffer);view[0] = 0x10000000000000000n;return view[0] === 0n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var buffer = new ArrayBuffer(64);var view = new BigUint64Array(buffer);view[0] = 0x10000000000000000n;return view[0] === 0n; }
§DataView.prototype.getBigInt64 ? function(){ var buffer = new ArrayBuffer(64);var view = new DataView(buffer);view.setBigInt64(0, 1n);return view.getBigInt64(0) === 1n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var buffer = new ArrayBuffer(64);var view = new DataView(buffer);view.setBigInt64(0, 1n);return view.getBigInt64(0) === 1n; }
§DataView.prototype.getBigUint64 ? function(){ var buffer = new ArrayBuffer(64);var view = new DataView(buffer);view.setBigUint64(0, 1n);return view.getBigUint64(0) === 1n; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var buffer = new ArrayBuffer(64);var view = new DataView(buffer);view.setBigUint64(0, 1n);return view.getBigUint64(0) === 1n; }

§Promise.allSettled ? function(){ Promise.allSettled([ Promise.resolve(1), Promise.reject(2), Promise.resolve(3)]).then(it => { if ( it.length === 3 && it[0].status === 'fulfilled' && it[0].value === 1 && it[1].status === 'rejected' && it[1].reason === 2 && it[2].status === 'fulfilled' && it[2].value === 3 ) asyncTestPassed();}); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ Promise.allSettled([ Promise.resolve(1), Promise.reject(2), Promise.resolve(3)]).then(it => { if ( it.length === 3 && it[0].status === 'fulfilled' && it[0].value === 1 && it[1].status === 'rejected' && it[1].reason === 2 && it[2].status === 'fulfilled' && it[2].value === 3 ) asyncTestPassed();}); }
§nullish coalescing operator (??) ? function(){ return (null ?? 42) === 42 && (undefined ?? 42) === 42 && (false ?? 42) === false && ('' ?? 42) === '' && (0 ?? 42) === 0 && isNaN(NaN ?? 42); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return (null ?? 42) === 42 && (undefined ?? 42) === 42 && (false ?? 42) === false && ('' ?? 42) === '' && (0 ?? 42) === 0 && isNaN(NaN ?? 42); }
globalThis
§"globalThis" global property is global object ? function(){ var actualGlobal = Function('return this')();actualGlobal.__system_global_test__ = 42;return typeof globalThis === 'object' && globalThis && globalThis === actualGlobal && !globalThis.lacksGlobalThis && globalThis.__system_global_test__ === 42; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ var actualGlobal = Function('return this')();actualGlobal.__system_global_test__ = 42;return typeof globalThis === 'object' && globalThis && globalThis === actualGlobal && !globalThis.lacksGlobalThis && globalThis.__system_global_test__ === 42; }
§"globalThis" global property has correct property descriptor ? function(){ var actualGlobal = Function('return this')();if (typeof globalThis !== 'object') { return false; }if (!('globalThis' in actualGlobal)) { return false; }if (Object.prototype.propertyIsEnumerable.call(actualGlobal, 'globalThis')) { return false; }var descriptor = Object.getOwnPropertyDescriptor(actualGlobal, 'globalThis');return descriptor.value === actualGlobal && !descriptor.enumerable && descriptor.configurable && descriptor.writable; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No Flag	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ var actualGlobal = Function('return this')();if (typeof globalThis !== 'object') { return false; }if (!('globalThis' in actualGlobal)) { return false; }if (Object.prototype.propertyIsEnumerable.call(actualGlobal, 'globalThis')) { return false; }var descriptor = Object.getOwnPropertyDescriptor(actualGlobal, 'globalThis');return descriptor.value === actualGlobal && !descriptor.enumerable && descriptor.configurable && descriptor.writable; }
optional chaining operator (?.)
§optional property access ? function(){ var foo = { baz: 42 };var bar = null;return foo?.baz === 42 && bar?.baz === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var foo = { baz: 42 };var bar = null;return foo?.baz === 42 && bar?.baz === void undefined; }
§optional bracket access ? function(){ var foo = { baz: 42 };var bar = null;return foo?.['baz'] === 42 && bar?.['baz'] === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var foo = { baz: 42 };var bar = null;return foo?.['baz'] === 42 && bar?.['baz'] === void undefined; }
§optional method call ? function(){ var foo = { baz: function () { return this.value; }, value: 42 };var bar = null;return foo?.baz() === 42 && bar?.baz() === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var foo = { baz: function () { return this.value; }, value: 42 };var bar = null;return foo?.baz() === 42 && bar?.baz() === void undefined; }
§optional function call ? function(){ var foo = { baz: function () { return 42; } };var bar = {};function baz() { return 42; };var n;return foo.baz?.() === 42 && bar.baz?.() === void undefined && baz?.() === 42 && n?.() === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var foo = { baz: function () { return 42; } };var bar = {};function baz() { return 42; };var n;return foo.baz?.() === 42 && bar.baz?.() === void undefined && baz?.() === 42 && n?.() === void undefined; }
§spread parameters after optional chaining ? function(){ var fn = null;var n = null;var o = {};return fn?.(...[], 1) === void undefined && fn?.(...[], ...[]) === void undefined && o.method?.(...[], 1) === void undefined && n?.method(...[], 1) === void undefined; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var fn = null;var n = null;var o = {};return fn?.(...[], 1) === void undefined && fn?.(...[], ...[]) === void undefined && o.method?.(...[], 1) === void undefined && n?.method(...[], 1) === void undefined; }


§String.prototype.replaceAll ? function(){ return 'q=query+string+parameters'.replaceAll('+', ' ') === 'q=query string parameters'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return 'q=query+string+parameters'.replaceAll('+', ' ') === 'q=query string parameters'; }
§numeric separators ? function(){ return 1_000_000.000_001 === 1000000.000001 && 0b1010_0001_1000_0101 === 0b1010000110000101; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return 1_000_000.000_001 === 1000000.000001 && 0b1010_0001_1000_0101 === 0b1010000110000101; }
Promise.any
§fulfillment ? function(){ Promise.any([ Promise.reject(1), Promise.resolve(2), Promise.resolve(3)]).then(it => { if (it === 2) asyncTestPassed();}); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ Promise.any([ Promise.reject(1), Promise.resolve(2), Promise.resolve(3)]).then(it => { if (it === 2) asyncTestPassed();}); }
§AggregateError ? function(){ Promise.any([ Promise.reject(1), Promise.reject(2), Promise.reject(3)]).catch (error => { if (error instanceof AggregateError && error.errors.length === 3) asyncTestPassed();}); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ Promise.any([ Promise.reject(1), Promise.reject(2), Promise.reject(3)]).catch (error => { if (error instanceof AggregateError && error.errors.length === 3) asyncTestPassed();}); }
WeakReferences
§WeakRef minimal support ? function(){ var O = {};var weakref = new WeakRef(O);return weakref.deref() === O; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var O = {};var weakref = new WeakRef(O);return weakref.deref() === O; }
§FinalizationRegistry minimal support ? function(){ var fr = new FinalizationRegistry(function () {});return Object.getPrototypeOf(fr) === FinalizationRegistry.prototype; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var fr = new FinalizationRegistry(function () {});return Object.getPrototypeOf(fr) === FinalizationRegistry.prototype; }
Logical Assignment
§\|\|= basic support ? function(){ let a;let b = 0;let c = 1;a \|\|= 2;b \|\|= 2;c \|\|= 2;return a === 2 && b === 2 && c === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a;let b = 0;let c = 1;a \|\|= 2;b \|\|= 2;c \|\|= 2;return a === 2 && b === 2 && c === 1; }
§\|\|= short-circuiting behaviour ? function(){ let a = 1;let i = 1;a \|\|= ++i;return a === 1 && i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a = 1;let i = 1;a \|\|= ++i;return a === 1 && i === 1; }
§\|\|= setter not unecessarily invoked ? function(){ let i = 1;var obj = { get x() { return 1 }, set x(n) { i++; } };obj.x \|\|= 2;return i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let i = 1;var obj = { get x() { return 1 }, set x(n) { i++; } };obj.x \|\|= 2;return i === 1; }
§&&= basic support ? function(){ let a;let b = 0;let c = 1;a &&= 2;b &&= 2;c &&= 2;return typeof a === 'undefined' && b === 0 && c === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a;let b = 0;let c = 1;a &&= 2;b &&= 2;c &&= 2;return typeof a === 'undefined' && b === 0 && c === 2; }
§&&= short-circuiting behaviour ? function(){ let a;let i = 1;a &&= ++i;return typeof a === 'undefined' && i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a;let i = 1;a &&= ++i;return typeof a === 'undefined' && i === 1; }
§&&= setter not unecessarily invoked ? function(){ let i = 1;var obj = { get x() { return }, set x(n) { i++; } };obj.x &&= 2;return i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let i = 1;var obj = { get x() { return }, set x(n) { i++; } };obj.x &&= 2;return i === 1; }
§??= basic support ? function(){ let a;let b = 0;let c = 1;a ??= 2;b ??= 2;c ??= 2;return a === 2 && b === 0 && c === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a;let b = 0;let c = 1;a ??= 2;b ??= 2;c ??= 2;return a === 2 && b === 0 && c === 1; }
§??= short-circuiting behaviour ? function(){ let a = 1;let i = 1;a ??= ++i;return a === 1 && i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let a = 1;let i = 1;a ??= ++i;return a === 1 && i === 1; }
§??= setter not unecessarily invoked ? function(){ let i = 1;var obj = { get x() { return 1 }, set x(n) { i++; } };obj.x ??= 2;return i === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ let i = 1;var obj = { get x() { return 1 }, set x(n) { i++; } };obj.x ??= 2;return i === 1; }

Array find from last
§Array.prototype.findLast ? function(){ var arr = [{ x: 1 }, { x: 2 }, { x: 1 }, { x: 2 }];return arr.findLast(function (o) { return o.x === 1; }) === arr[2]; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = [{ x: 1 }, { x: 2 }, { x: 1 }, { x: 2 }];return arr.findLast(function (o) { return o.x === 1; }) === arr[2]; }
§Array.prototype.findLastIndex ? function(){ var arr = [{ x: 1 }, { x: 2 }, { x: 1 }, { x: 2 }];return arr.findLastIndex(function (o) { return o.x === 1; }) === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = [{ x: 1 }, { x: 2 }, { x: 1 }, { x: 2 }];return arr.findLastIndex(function (o) { return o.x === 1; }) === 2; }

§Hashbang Grammar ? function(){ try { return !eval('#!/wash/your/hands');} catch (e) { return false} }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ try { return !eval('#!/wash/your/hands');} catch (e) { return false} }
Change Array by copy
§Array.prototype.toReversed() ? function(){ var arr = [1, 2, 3];return arr.toReversed()[0] === 3 && arr[0] === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = [1, 2, 3];return arr.toReversed()[0] === 3 && arr[0] === 1; }
§Array.prototype.toSorted() ? function(){ var arr = ['C', 'A', 'B'];return arr.toSorted()[0] === 'A' && arr[0] === 'C'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = ['C', 'A', 'B'];return arr.toSorted()[0] === 'A' && arr[0] === 'C'; }
§Array.prototype.toSpliced() ? function(){ var arr = ['A', 'C'];return arr.toSpliced(1, 0, 'B')[1] === 'B' && arr[1] === 'C'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = ['A', 'C'];return arr.toSpliced(1, 0, 'B')[1] === 'B' && arr[1] === 'C'; }
§Array.prototype.with() ? function(){ var arr = ['A', 'X', 'C'];return arr.with(1, 'B')[1] === 'B' && arr[1] === 'X'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = ['A', 'X', 'C'];return arr.with(1, 'B')[1] === 'B' && arr[1] === 'X'; }
§TypedArray.prototype.toReversed() ? function(){ var arr = new Uint8Array([1, 2, 3]);return arr.toReversed()[0] == 3 && arr[0] == 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = new Uint8Array([1, 2, 3]);return arr.toReversed()[0] == 3 && arr[0] == 1; }
§TypedArray.prototype.toSorted() ? function(){ var arr = new Uint8Array([3, 1, 2]);return arr.toSorted()[0] == 1 && arr[0] == 3; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = new Uint8Array([3, 1, 2]);return arr.toSorted()[0] == 1 && arr[0] == 3; }
§TypedArray.prototype.with() ? function(){ var arr = new Uint8Array([1, 0, 2]);return arr.with(1, 2)[1] == 2 && arr[1] == 0; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var arr = new Uint8Array([1, 0, 2]);return arr.with(1, 2)[1] == 2 && arr[1] == 0; }

RegExp `v` flag
§set notations ? function(){ return /[\p{ASCII}&&\p{Decimal_Number}]/v.test("0")&& /[\p{Any}--[\x01-\u{10ffff}]]/v.test("\0") }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /[\p{ASCII}&&\p{Decimal_Number}]/v.test("0")&& /[\p{Any}--[\x01-\u{10ffff}]]/v.test("\0") }
§properties of Strings ? function(){ return /^\p{Emoji_Keycap_Sequence}$/v.test("\uFE0F\u20E3")&& !/^\p{Emoji_Keycap_Sequence}$/v.test(""); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /^\p{Emoji_Keycap_Sequence}$/v.test("\uFE0F\u20E3")&& !/^\p{Emoji_Keycap_Sequence}$/v.test(""); }
§constructor supports it ? function(){ return new RegExp('a', 'v') instanceof RegExp; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return new RegExp('a', 'v') instanceof RegExp; }
§shows up in flags ? function(){ var flags = [];var p = new Proxy({}, { get: function (o, k) { flags.push(k); return o[k]; }});Object.getOwnPropertyDescriptor(RegExp.prototype, 'flags').get.call(p);return flags.indexOf("unicodeSets") !== -1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error	Error Error	Error Error	Error Error
	function(){ var flags = [];var p = new Proxy({}, { get: function (o, k) { flags.push(k); return o[k]; }});Object.getOwnPropertyDescriptor(RegExp.prototype, 'flags').get.call(p);return flags.indexOf("unicodeSets") !== -1; }
§Unicode 15.1 ? function(){ return /^\p{RGI_Emoji}$/v.test("🐦‍🔥"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	Yes Yes	Yes Yes	No No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /^\p{RGI_Emoji}$/v.test("🐦‍🔥"); }
§Unicode 16.0 ? function(){ return /^\p{RGI_Emoji}$/v.test("🇨🇶"); }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	No No	Yes Yes	No No	No No	No No	Yes Yes	No No	No No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /^\p{RGI_Emoji}$/v.test("🇨🇶"); }
§Unicode 17.0 ? function(){ return /^\p{RGI_Emoji}$/v.test("🧑‍🩰‍🏽"); }	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ return /^\p{RGI_Emoji}$/v.test("🧑‍🩰‍🏽"); }
ArrayBuffer.prototype.transfer
§ArrayBuffer.prototype.transfer() ? function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transfer();return buffer1.byteLength === 0 && buffer2.byteLength === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transfer();return buffer1.byteLength === 0 && buffer2.byteLength === 2; }
§ArrayBuffer.prototype.transferToFixedLength() ? function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transferToFixedLength();return buffer1.byteLength === 0 && buffer2.byteLength === 2; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transferToFixedLength();return buffer1.byteLength === 0 && buffer2.byteLength === 2; }
§ArrayBuffer.prototype.detached ? function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transfer();return buffer1.detached && !buffer2.detached; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Flag	Error No	Error No	Error No	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const buffer1 = new Uint8Array([1, 2]).buffer;const buffer2 = buffer1.transfer();return buffer1.detached && !buffer2.detached; }

§Promise.withResolvers ? function(){ var obj = Promise.withResolvers();return obj instanceof Object && obj.promise instanceof Promise && typeof obj.resolve === 'function' && typeof obj.reject === 'function'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Flag	Error Flag	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var obj = Promise.withResolvers();return obj instanceof Object && obj.promise instanceof Promise && typeof obj.resolve === 'function' && typeof obj.reject === 'function'; }
Array Grouping
§Object.groupBy() ? function(){ const array = [1, 2, 3, 4];const obj = Object.groupBy(array, (num, index) => { return num % 2 === 0 ? 'even': 'odd';});return !('toString' in obj) && obj.even[0] == 2 && obj.odd[0] == 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const array = [1, 2, 3, 4];const obj = Object.groupBy(array, (num, index) => { return num % 2 === 0 ? 'even': 'odd';});return !('toString' in obj) && obj.even[0] == 2 && obj.odd[0] == 1; }
§Map.groupBy() ? function(){ const array = [1, 2, 3, 4];const odd = { odd: true };const even = { even: true };const map = Map.groupBy(array, (num, index) => { return num % 2 === 0 ? even: odd;});return map instanceof Map && map.get(even)[0] === 2 && map.get(odd)[0] === 1; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const array = [1, 2, 3, 4];const odd = { odd: true };const even = { even: true };const map = Map.groupBy(array, (num, index) => { return num % 2 === 0 ? even: odd;});return map instanceof Map && map.get(even)[0] === 2 && map.get(odd)[0] === 1; }

Class and Property Decorators
§class decorators ? function(){ class A { @nonconf get B() {}}function nonconf(target, name, descriptor) { descriptor.configurable = false; return descriptor;}return Object.getOwnPropertyDescriptor(A.prototype, "B").configurable === false; }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ class A { @nonconf get B() {}}function nonconf(target, name, descriptor) { descriptor.configurable = false; return descriptor;}return Object.getOwnPropertyDescriptor(A.prototype, "B").configurable === false; }
Legacy RegExp features in JavaScript
§RegExp "lastMatch" ? function(){ var re = /\w/;re.exec('x');return RegExp.lastMatch === 'x'; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ var re = /\w/;re.exec('x');return RegExp.lastMatch === 'x'; }
§RegExp.$1-$9 ? function(){ for (var i = 1; i < 10; i++) { if (!(('$' + i) in RegExp)) return false;}return true; }	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes	Yes Yes
	function(){ for (var i = 1; i < 10; i++) { if (!(('$' + i) in RegExp)) return false;}return true; }
Uint8Array to/from base64 and hex
§Uint8Array.toBase64() ? function(){ const arr = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);return arr.toBase64() === "SGVsbG8gV29ybGQ="; }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);return arr.toBase64() === "SGVsbG8gV29ybGQ="; }
§Uint8Array.fromBase64() ? function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);const arr2 = Uint8Array.fromBase64("SGVsbG8gV29ybGQ=");return arr1.length === arr2.length && arr1.every((element, index) => element === arr2[index]); }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);const arr2 = Uint8Array.fromBase64("SGVsbG8gV29ybGQ=");return arr1.length === arr2.length && arr1.every((element, index) => element === arr2[index]); }
§Uint8Array.setFromBase64() ? function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);let arr2 = new Uint8Array(16);let { read, written } = arr2.setFromBase64("SGVsbG8gV29ybGQ=");return read == 16 && written == 11 && arr1.every((element, index) => element === arr2[index]); }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);let arr2 = new Uint8Array(16);let { read, written } = arr2.setFromBase64("SGVsbG8gV29ybGQ=");return read == 16 && written == 11 && arr1.every((element, index) => element === arr2[index]); }
§Uint8Array.toHex() ? function(){ const arr = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);return arr.toHex() === "48656c6c6f20576f726c64"; }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);return arr.toHex() === "48656c6c6f20576f726c64"; }
§Uint8Array.fromHex() ? function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);const arr2 = Uint8Array.fromHex("48656c6c6f20576f726c64");return arr1.length === arr2.length && arr1.every((element, index) => element === arr2[index]); }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);const arr2 = Uint8Array.fromHex("48656c6c6f20576f726c64");return arr1.length === arr2.length && arr1.every((element, index) => element === arr2[index]); }
§Uint8Array.setFromHex() ? function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);let arr2 = new Uint8Array(16);let { read, written } = arr2.setFromHex("48656c6c6f20576f726c64");return read == 22 && written == 11 && arr1.every((element, index) => element === arr2[index]); }	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const arr1 = new Uint8Array([72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]);let arr2 = new Uint8Array(16);let { read, written } = arr2.setFromHex("48656c6c6f20576f726c64");return read == 22 && written == 11 && arr1.every((element, index) => element === arr2[index]); }
Explicit Resource Management
§using ? function(){ var resource = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};{ using _ = resource;}return resource.disposed }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var resource = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};{ using _ = resource;}return resource.disposed }
§for (using ... of ? function(){ var resource1 = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};var resource2 = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};{ for (using _ of [resource1, resource2]);}return resource1.disposed && resource2.disposed; }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var resource1 = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};var resource2 = { disposed: false, [Symbol.dispose]() { this.disposed = true; }};{ for (using _ of [resource1, resource2]);}return resource1.disposed && resource2.disposed; }
§await using ? function(){ (async function () { var resource = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; } }; { await using _ = resource; } return resource.disposed && asyncTestPassed();}()); }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ (async function () { var resource = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; } }; { await using _ = resource; } return resource.disposed && asyncTestPassed();}()); }
§for (await using ... of ? function(){ var resource1 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; }};var resource2 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; }};(async function () { for (await using _ of [resource1, resource2]); return resource1.disposed && resource2.disposed && asyncTestPassed();}()); }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var resource1 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; }};var resource2 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true; }};(async function () { for (await using _ of [resource1, resource2]); return resource1.disposed && resource2.disposed && asyncTestPassed();}()); }
§SuppressedError ? function(){ var err1 = new Error();var err2 = new Error();var err3 = new Error();try { using _1 = { [Symbol.dispose]() { throw err1 } }, _2 = { [Symbol.dispose]() { throw err2 } }; throw err3;} catch (e) { return ( e instanceof SuppressedError && e.error === err1 && e.suppressed instanceof SuppressedError && e.suppressed.error === err2 && e.suppressed.suppressed === err3 );} }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var err1 = new Error();var err2 = new Error();var err3 = new Error();try { using _1 = { [Symbol.dispose]() { throw err1 } }, _2 = { [Symbol.dispose]() { throw err2 } }; throw err3;} catch (e) { return ( e instanceof SuppressedError && e.error === err1 && e.suppressed instanceof SuppressedError && e.suppressed.error === err2 && e.suppressed.suppressed === err3 );} }
§DisposableStack ? function(){ var stack1 = new DisposableStack();var resource1 = { disposed: false };var resource2 = { disposed: false };var resource3 = { disposed: false, [Symbol.dispose]() { this.disposed = true } };var adopted = stack1.adopt(resource1, function (r) { r.disposed = true });var deferred = stack1.defer(function (r) { resource2.disposed = true });var stack2 = stack1.move();var used = stack2.use(resource3);stack2.dispose();return ( resource1.disposed && adopted === resource1 && resource2.disposed && deferred === undefined && resource3.disposed && used === resource3); }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var stack1 = new DisposableStack();var resource1 = { disposed: false };var resource2 = { disposed: false };var resource3 = { disposed: false, [Symbol.dispose]() { this.disposed = true } };var adopted = stack1.adopt(resource1, function (r) { r.disposed = true });var deferred = stack1.defer(function (r) { resource2.disposed = true });var stack2 = stack1.move();var used = stack2.use(resource3);stack2.dispose();return ( resource1.disposed && adopted === resource1 && resource2.disposed && deferred === undefined && resource3.disposed && used === resource3); }
§AsyncDisposableStack ? function(){ var stack1 = new AsyncDisposableStack();var resource1 = { disposed: false };var resource2 = { disposed: false };var resource3 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true } };var adopted = stack1.adopt(resource1, async function (r) { r.disposed = true });var deferred = stack1.defer(async function (r) { resource2.disposed = true });var stack2 = stack1.move();var used = stack2.use(resource3);stack2.disposeAsync().then(function () { resource1.disposed && adopted === resource1 && resource2.disposed && deferred === undefined && resource3.disposed && used === resource3 && asyncTestPassed();}); }	Yes Yes	Yes Yes	Yes Yes	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ var stack1 = new AsyncDisposableStack();var resource1 = { disposed: false };var resource2 = { disposed: false };var resource3 = { disposed: false, async [Symbol.asyncDispose]() { this.disposed = true } };var adopted = stack1.adopt(resource1, async function (r) { r.disposed = true });var deferred = stack1.defer(async function (r) { resource2.disposed = true });var stack2 = stack1.move();var used = stack2.use(resource3);stack2.disposeAsync().then(function () { resource1.disposed && adopted === resource1 && resource2.disposed && deferred === undefined && resource3.disposed && used === resource3 && asyncTestPassed();}); }


§ShadowRealm ? function(){ return typeof ShadowRealm === "function" && ["evaluate", "importValue"].every(function(key){ return key in ShadowRealm.prototype; }); }	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No	No No
	function(){ return typeof ShadowRealm === "function" && ["evaluate", "importValue"].every(function(key){ return key in ShadowRealm.prototype; }); }
Map.prototype.upsert
§Map.prototype.upsert ? function(){ const map = new Map([['a', 1]]);if (map.upsert('a', it => 2, () => 3) !== 2) return false;if (map.upsert('b', it => 2, () => 3) !== 3) return false;return Array.from(map).join() === 'a,2,b,3'; }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const map = new Map([['a', 1]]);if (map.upsert('a', it => 2, () => 3) !== 2) return false;if (map.upsert('b', it => 2, () => 3) !== 3) return false;return Array.from(map).join() === 'a,2,b,3'; }
§WeakMap.prototype.upsert ? function(){ const a = {}, b = {};const map = new WeakMap([[a, 1]]);if (map.upsert(a, it => 2, () => 3) !== 2) return false;if (map.upsert(b, it => 2, () => 3) !== 3) return false;return map.get(a) === 2 && map.get(b) === 3; }	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error	Error Error
	function(){ const a = {}, b = {};const map = new WeakMap([[a, 1]]);if (map.upsert(a, it => 2, () => 3) !== 2) return false;if (map.upsert(b, it => 2, () => 3) !== 3) return false;return map.get(a) === 2 && map.get(b) === 3; }