Less than or equal (<=)

BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

Theless than or equal (<=) operator returnstrue if the left operand is less than or equal to the right operand, andfalse otherwise.

Try it

console.log(5 <= 3);// Expected output: falseconsole.log(3 <= 3);// Expected output: true// Compare bigint to numberconsole.log(3n <= 5);// Expected output: trueconsole.log("aa" <= "ab");// Expected output: true

Syntax

x <= y

The operands are compared using the same algorithm as theLess than operator, with the operands swapped and the result negated.x <= y is generally equivalent to!(y < x), except for two cases wherex <= y andx > y are bothfalse:

If one of the operands gets converted to a BigInt, while the other gets converted to a string that cannot be converted to a BigInt value (it throws asyntax error when passed toBigInt()).
If one of the operands gets converted toNaN. (For example, strings that cannot be converted to numbers, orundefined.)

In addition,x <= y coercesx to a primitive beforey, whiley < x coercesy to a primitive beforex. Because coercion may have side effects, the order of the operands may matter.

x <= y is generally equivalent tox < y || x == y, except for a few cases:

When one ofx ory isnull, and the other is something that's notnull and becomes 0 whencoerced to numeric (including0,0n,false,"","0",new Date(0), etc.):x <= y istrue, whilex < y || x == y isfalse.
When one ofx ory isundefined, and the other is one ofnull orundefined:x <= y isfalse, whilex == y istrue.
Whenx andy are the same object that becomesNaN after the first step ofLess than (such asnew Date(NaN)):x <= y isfalse, whilex == y istrue.
Whenx andy are different objects that become the same value after the first step ofLess than:x <= y istrue, whilex < y || x == y isfalse.

Examples

String to string comparison

"a" <= "b"; // true"a" <= "a"; // true"a" <= "3"; // false

String to number comparison

"5" <= 3; // false"3" <= 3; // true"3" <= 5; // true"hello" <= 5; // false5 <= "hello"; // false

Number to Number comparison

5 <= 3; // false3 <= 3; // true3 <= 5; // true

Number to BigInt comparison

5n <= 3; // false3 <= 3n; // true3 <= 5n; // true

Comparing Boolean, null, undefined, NaN

true <= false; // falsetrue <= true; // truefalse <= true; // truetrue <= 0; // falsetrue <= 1; // truenull <= 0; // true1 <= null; // falseundefined <= 3; // false3 <= undefined; // false3 <= NaN; // falseNaN <= 3; // false