I highly recommend reading this:So, what's next?

core-js@3, babel and a look into the future

Raising funds

import'core-js/actual';Promise.resolve(42).then(it=>console.log(it));// => 42Array.from(newSet([1,2,3]).union(newSet([3,4,5])));// => [1, 2, 3, 4, 5][1,2].flatMap(it=>[it,it]);// => [1, 1, 2, 2](function*(i){while(true)yieldi++;})(1).drop(1).take(5).filter(it=>it%2).map(it=>it**2).toArray();// => [9, 25]structuredClone(newSet([1,2,3]));// => new Set([1, 2, 3])

import'core-js/actual/promise';import'core-js/actual/set';import'core-js/actual/iterator';import'core-js/actual/array/from';import'core-js/actual/array/flat-map';import'core-js/actual/structured-clone';Promise.resolve(42).then(it=>console.log(it));// => 42Array.from(newSet([1,2,3]).union(newSet([3,4,5])));// => [1, 2, 3, 4, 5][1,2].flatMap(it=>[it,it]);// => [1, 1, 2, 2](function*(i){while(true)yieldi++;})(1).drop(1).take(5).filter(it=>it%2).map(it=>it**2).toArray();// => [9, 25]structuredClone(newSet([1,2,3]));// => new Set([1, 2, 3])

importPromisefrom'core-js-pure/actual/promise';importSetfrom'core-js-pure/actual/set';importIteratorfrom'core-js-pure/actual/iterator';importfromfrom'core-js-pure/actual/array/from';importflatMapfrom'core-js-pure/actual/array/flat-map';importstructuredClonefrom'core-js-pure/actual/structured-clone';Promise.resolve(42).then(it=>console.log(it));// => 42from(newSet([1,2,3]).union(newSet([3,4,5])));// => [1, 2, 3, 4, 5]flatMap([1,2],it=>[it,it]);// => [1, 1, 2, 2]Iterator.from(function*(i){while(true)yieldi++;}(1)).drop(1).take(5).filter(it=>it%2).map(it=>it**2).toArray();// => [9, 25]structuredClone(newSet([1,2,3]));// => new Set([1, 2, 3])

Index

Usage⬆

Installation:⬆

// global versionnpm install --save core-js@3.44.0// version without global namespace pollutionnpm install --save core-js-pure@3.44.0// bundled global versionnpm install --save core-js-bundle@3.44.0

postinstall message⬆

ADBLOCK=true npm install// orDISABLE_OPENCOLLECTIVE=true npm install// ornpm install --loglevel silent

CommonJS API⬆

// polyfill all `core-js` features, including early-stage proposals:import"core-js";// or:import"core-js/full";// polyfill all actual features - stable ES, web standards and stage 3 ES proposals:import"core-js/actual";// polyfill only stable features - ES and web standards:import"core-js/stable";// polyfill only stable ES features:import"core-js/es";// if you want to polyfill `Set`:// all `Set`-related features, with early-stage ES proposals:import"core-js/full/set";// stable required for `Set` ES features, features from web standards and stage 3 ES proposals:import"core-js/actual/set";// stable required for `Set` ES features and features from web standards// (DOM collections iterator in this case):import"core-js/stable/set";// only stable ES features required for `Set`:import"core-js/es/set";// the same without global namespace pollution:importSetfrom"core-js-pure/full/set";importSetfrom"core-js-pure/actual/set";importSetfrom"core-js-pure/stable/set";importSetfrom"core-js-pure/es/set";// if you want to polyfill just the required methods:import"core-js/full/set/intersection";import"core-js/actual/array/find-last";import"core-js/stable/queue-microtask";import"core-js/es/array/from";// polyfill iterator helpers proposal:import"core-js/proposals/iterator-helpers";// polyfill all stage 2+ proposals:import"core-js/stage/2";

Tip

The usage of the/actual/ namespace is recommended since it includes all actual JavaScript features and does not include unstable early-stage proposals that are available mainly for experiments.

Warning

• Themodules path is an internal API, does not inject all required dependencies and can be changed in minor or patch releases. Use it only for a custom build and/or if you know what are you doing.
• If you usecore-js with the extension of native objects, recommended to load allcore-js modules at the top of the entry point of your application, otherwise, you can have conflicts.
  • For example, Google Maps use their ownSymbol.iterator, conflicting withArray.from,URLSearchParams and / or something else fromcore-js, seerelated issues.
  • Such conflicts are also resolvable by discovering and manually adding each conflicting entry fromcore-js.
• core-js is extremely modular and uses a lot of very tiny modules, because of that for usage in browsers bundle upcore-js instead of a usage loader for each file, otherwise, you will have hundreds of requests.

CommonJS and prototype methods without global namespace pollution⬆

importfillfrom'core-js-pure/actual/array/virtual/fill';importfindIndexfrom'core-js-pure/actual/array/virtual/find-index';Array(10)::fill(0).map((a,b)=>b*b)::findIndex(it=>it&&!(it%8));// => 4

Warning

The bind operator is an early-stage ECMAScript proposal and usage of this syntax can be dangerous.

Babel⬆

@babel/polyfill⬆

import'core-js/stable';import'regenerator-runtime/runtime';

@babel/preset-env⬆

Important

It is recommended to specify the used minorcore-js version, likecorejs: '3.44', instead ofcorejs: 3, since withcorejs: 3 will not be injected modules which were added in minorcore-js releases.

import'core-js/stable';

import'core-js/modules/es.array.unscopables.flat';import'core-js/modules/es.array.unscopables.flat-map';import'core-js/modules/es.object.from-entries';import'core-js/modules/web.immediate';

import'core-js/es';import'core-js/proposals/set-methods';import'core-js/full/set/map';

import'core-js/modules/es.array.unscopables.flat';import'core-js/modules/es.array.unscopables.flat-map';import'core-js/modules/es.object.from-entries';import'core-js/modules/esnext.set.difference';import'core-js/modules/esnext.set.intersection';import'core-js/modules/esnext.set.is-disjoint-from';import'core-js/modules/esnext.set.is-subset-of';import'core-js/modules/esnext.set.is-superset-of';import'core-js/modules/esnext.set.map';import'core-js/modules/esnext.set.symmetric-difference';import'core-js/modules/esnext.set.union';

// first file:letset=newSet([1,2,3]);

// second file:letarray=Array.of(1,2,3);

// first file:import'core-js/modules/es.array.iterator';import'core-js/modules/es.object.to-string';import'core-js/modules/es.set';varset=newSet([1,2,3]);

// second file:import'core-js/modules/es.array.of';vararray=Array.of(1,2,3);

Important

In the case ofuseBuiltIns: 'usage', you should not addcore-js imports by yourself, they will be added automatically.

@babel/runtime⬆

importfromfrom'core-js-pure/stable/array/from';importflatfrom'core-js-pure/stable/array/flat';importSetfrom'core-js-pure/stable/set';importPromisefrom'core-js-pure/stable/promise';from(newSet([1,2,3,2,1]));flat([1,[2,3],[4,[5]]],2);Promise.resolve(32).then(x=>console.log(x));

Array.from(newSet([1,2,3,2,1]));[1,[2,3],[4,[5]]].flat(2);Promise.resolve(32).then(x=>console.log(x));

Warning

If you use@babel/preset-env and@babel/runtime together, usecorejs option only in one place since it's duplicate functionality and will cause conflicts.

swc⬆

{"env": {"targets":"> 0.25%, not dead","mode":"entry","coreJs":"3.44"  }}

Configurable level of aggressiveness⬆

constconfigurator=require('core-js/configurator');configurator({useNative:['Promise'],// polyfills will be used only if natives are completely unavailableusePolyfill:['Array.from','String.prototype.padEnd'],// polyfills will be used anywayuseFeatureDetection:['Map','Set'],// default behavior});require('core-js/actual');

Custom build⬆

Supported engines and compatibility data⬆

Features:⬆

core-js(-pure)

ECMAScript⬆

core-js(-pure)/es

ECMAScript: Object⬆

classObject{toString():string;// ES2015+ fix: @@toStringTag support__defineGetter__(property:PropertyKey,getter:Function):void;__defineSetter__(property:PropertyKey,setter:Function):void;__lookupGetter__(property:PropertyKey):Function|void;__lookupSetter__(property:PropertyKey):Function|void;__proto__:Object|null;// required a way setting of prototype - will not in IE10-, it's for modern engines like Denostaticassign(target:Object, ...sources:Array<Object>):Object;staticcreate(prototype:Object|null,properties?:{[property:PropertyKey]:PropertyDescriptor}):Object;staticdefineProperties(object:Object,properties:{[property:PropertyKey]:PropertyDescriptor})):Object;staticdefineProperty(object:Object,property:PropertyKey,attributes:PropertyDescriptor):Object;staticentries(object:Object):Array<[string,mixed]>;staticfreeze(object:any):any;staticfromEntries(iterable:Iterable<[key,value]>):Object;staticgetOwnPropertyDescriptor(object:any,property:PropertyKey):PropertyDescriptor|void;staticgetOwnPropertyDescriptors(object:any):{[property:PropertyKey]:PropertyDescriptor};staticgetOwnPropertyNames(object:any):Array<string>;staticgetPrototypeOf(object:any):Object|null;staticgroupBy(items:Iterable,callbackfn:(value:any,index:number)=>key):{[key]:Array<mixed>};statichasOwn(object:object,key:PropertyKey):boolean;staticis(value1:any,value2:any):boolean;staticisExtensible(object:any):boolean;staticisFrozen(object:any):boolean;staticisSealed(object:any):boolean;statickeys(object:any):Array<string>;staticpreventExtensions(object:any):any;staticseal(object:any):any;staticsetPrototypeOf(target:any,prototype:Object|null):any;// required __proto__ - IE11+staticvalues(object:any):Array<mixed>;}

core-js(-pure)/es|stable|actual|full/objectcore-js(-pure)/es|stable|actual|full/object/assigncore-js(-pure)/es|stable|actual|full/object/iscore-js(-pure)/es|stable|actual|full/object/set-prototype-ofcore-js(-pure)/es|stable|actual|full/object/get-prototype-ofcore-js(-pure)/es|stable|actual|full/object/createcore-js(-pure)/es|stable|actual|full/object/define-propertycore-js(-pure)/es|stable|actual|full/object/define-propertiescore-js(-pure)/es|stable|actual|full/object/get-own-property-descriptorcore-js(-pure)/es|stable|actual|full/object/get-own-property-descriptorscore-js(-pure)/es|stable|actual|full/object/group-bycore-js(-pure)/es|stable|actual|full/object/has-owncore-js(-pure)/es|stable|actual|full/object/keyscore-js(-pure)/es|stable|actual|full/object/valuescore-js(-pure)/es|stable|actual|full/object/entriescore-js(-pure)/es|stable|actual|full/object/get-own-property-namescore-js(-pure)/es|stable|actual|full/object/freezecore-js(-pure)/es|stable|actual|full/object/from-entriescore-js(-pure)/es|stable|actual|full/object/sealcore-js(-pure)/es|stable|actual|full/object/prevent-extensionscore-js/es|stable|actual|full/object/protocore-js(-pure)/es|stable|actual|full/object/is-frozencore-js(-pure)/es|stable|actual|full/object/is-sealedcore-js(-pure)/es|stable|actual|full/object/is-extensiblecore-js/es|stable|actual|full/object/to-stringcore-js(-pure)/es|stable|actual|full/object/define-gettercore-js(-pure)/es|stable|actual|full/object/define-settercore-js(-pure)/es|stable|actual|full/object/lookup-gettercore-js(-pure)/es|stable|actual|full/object/lookup-setter

letfoo={q:1,w:2};letbar={e:3,r:4};letbaz={t:5,y:6};Object.assign(foo,bar,baz);// => foo = { q: 1, w: 2, e: 3, r: 4, t: 5, y: 6 }Object.is(NaN,NaN);// => trueObject.is(0,-0);// => falseObject.is(42,42);// => trueObject.is(42,'42');// => falsefunctionParent(){/* empty */}functionChild(){/* empty */}Object.setPrototypeOf(Child.prototype,Parent.prototype);newChild()instanceofChild;// => truenewChild()instanceofParent;// => true({[Symbol.toStringTag]:'Foo',}).toString();// => '[object Foo]'Object.keys('qwe');// => ['0', '1', '2']Object.getPrototypeOf('qwe')===String.prototype;// => trueObject.values({a:1,b:2,c:3});// => [1, 2, 3]Object.entries({a:1,b:2,c:3});// => [['a', 1], ['b', 2], ['c', 3]]for(let[key,value]ofObject.entries({a:1,b:2,c:3})){console.log(key);// => 'a', 'b', 'c'console.log(value);// => 1, 2, 3}// Shallow object cloning with prototype and descriptors:letcopy=Object.create(Object.getPrototypeOf(object),Object.getOwnPropertyDescriptors(object));// Mixin:Object.defineProperties(target,Object.getOwnPropertyDescriptors(source));constmap=newMap([['a',1],['b',2]]);Object.fromEntries(map);// => { a: 1, b: 2 }classUnit{constructor(id){this.id=id;}toString(){return`unit${this.id}`;}}constunits=newSet([newUnit(101),newUnit(102)]);Object.fromEntries(units.entries());// => { unit101: Unit { id: 101 }, unit102: Unit { id: 102 }}Object.hasOwn({foo:42},'foo');// => trueObject.hasOwn({foo:42},'bar');// => falseObject.hasOwn({},'toString');// => falseObject.groupBy([1,2,3,4,5],it=>it%2);// => { 1: [1, 3, 5], 0: [2, 4] }

ECMAScript: Function⬆

classFunction{name:string;bind(thisArg:any, ...args:Array<mixed>):Function;  @@hasInstance(value: any):boolean;}

core-js/es|stable|actual|full/functioncore-js/es|stable|actual|full/function/namecore-js/es|stable|actual|full/function/has-instancecore-js(-pure)/es|stable|actual|full/function/bindcore-js(-pure)/es|stable|actual|full/function/virtual/bind

(functionfoo(){/* empty */}).name;// => 'foo'console.log.bind(console,42)(43);// => 42 43

ECMAScript: Error⬆

classError{staticisError(value:any):boolean;constructor(message:string,{cause:any}):%Error%;toString():string;// different fixes}class[EvalError,RangeError,ReferenceError,SyntaxError,TypeError,URIError,WebAssembly.CompileError,WebAssembly.LinkError,WebAssembly.RuntimeError,]extendsError{constructor(message: string,{cause:any}):%Error%;}classAggregateErrorextendsError{constructor(errors:Iterable,message?:string,{cause:any}?):AggregateError;errors:Array<any>;message:string;cause:any;}classSuppressedErrorextendsError{constructor(error:any,suppressed:any,message?:string):SuppressedError;error:any;suppressed:any;message:string;}

core-js/es|stable|actual|full/errorcore-js/es|stable|actual|full/error/constructorcore-js(-pure)/es|stable|actual|full/error/is-errorcore-js/es|stable|actual|full/error/to-stringcore-js(-pure)/es|stable|actual|full/aggregate-errorcore-js(-pure)/es|stable|actual|full/suppressed-error

consterror1=newTypeError('Error 1');consterror2=newTypeError('Error 2');constaggregate=newAggregateError([error1,error2],'Collected errors');aggregate.errors[0]===error1;// => trueaggregate.errors[1]===error2;// => trueconstcause=newTypeError('Something wrong');consterror=newTypeError('Here explained what`s wrong',{ cause});error.cause===cause;// => trueError.prototype.toString.call({message:1,name:2})==='2: 1';// => true

Error.isError(newError('error'));// => trueError.isError(newTypeError('error'));// => trueError.isError(newDOMException('error'));// => trueError.isError(null);// => falseError.isError({});// => falseError.isError(Object.create(Error.prototype));// => false

Warning

We have no bulletproof way to polyfill thisError.isError / check if the object is an error, so it's an enough naive implementation.

ECMAScript: Array⬆

classArray{at(index:int):any;concat(...args:Array<mixed>):Array<mixed>;// with adding support of @@isConcatSpreadable and @@speciescopyWithin(target:number,start:number,end?:number): this;entries():Iterator<[index,value]>;every(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):boolean;fill(value:any,start?:number,end?:number): this;filter(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):Array<mixed>;// with adding support of @@speciesfind(callbackfn:(value:any,index:number,target:any)=>boolean),thisArg?:any):any;findIndex(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):uint;findLast(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):any;findLastIndex(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):uint;flat(depthArg?:number=1):Array<mixed>;flatMap(mapFn:(value:any,index:number,target:any)=>any,thisArg:any):Array<mixed>;forEach(callbackfn:(value:any,index:number,target:any)=>void,thisArg?:any):void;includes(searchElement:any,from?:number):boolean;indexOf(searchElement:any,from?:number):number;join(separator:string=','):string;keys():Iterator<index>;lastIndexOf(searchElement:any,from?:number):number;map(mapFn:(value:any,index:number,target:any)=>any,thisArg?:any):Array<mixed>;// with adding support of @@speciespush(...args:Array<mixed>):uint;reduce(callbackfn:(memo:any,value:any,index:number,target:any)=>any,initialValue?:any):any;reduceRight(callbackfn:(memo:any,value:any,index:number,target:any)=>any,initialValue?:any):any;reverse(): this;// Safari 12.0 bug fixslice(start?:number,end?:number):Array<mixed>;// with adding support of @@speciessplice(start?:number,deleteCount?:number, ...items:Array<mixed>):Array<mixed>;// with adding support of @@speciessome(callbackfn:(value:any,index:number,target:any)=>boolean,thisArg?:any):boolean;sort(comparefn?:(a:any,b:any)=>number): this;// with modern behavior like stable sorttoReversed():Array<mixed>;toSpliced(start?:number,deleteCount?:number, ...items:Array<mixed>):Array<mixed>;toSorted(comparefn?:(a:any,b:any)=>number):Array<mixed>;unshift(...args:Array<mixed>):uint;values():Iterator<value>;with(index:includes,value:any):Array<mixed>;  @@iterator():Iterator<value>;  @@unscopables:{[newMethodNames:string]:true};staticfrom(items:Iterable|ArrayLike,mapFn?:(value:any,index:number)=>any,thisArg?:any):Array<mixed>;staticfromAsync(asyncItems:AsyncIterable|Iterable|ArrayLike,mapfn?:(value:any,index:number)=>any,thisArg?:any):Array;staticisArray(value:any):boolean;staticof(...args:Array<mixed>):Array<mixed>;}classArguments{  @@iterator():Iterator<value>;// available only in core-js methods}

core-js(-pure)/es|stable|actual|full/arraycore-js(-pure)/es|stable|actual|full/array/fromcore-js(-pure)/es|stable|actual|full/array/from-asynccore-js(-pure)/es|stable|actual|full/array/ofcore-js(-pure)/es|stable|actual|full/array/is-arraycore-js(-pure)/es|stable|actual|full/array(/virtual)/atcore-js(-pure)/es|stable|actual|full/array(/virtual)/concatcore-js(-pure)/es|stable|actual|full/array(/virtual)/copy-withincore-js(-pure)/es|stable|actual|full/array(/virtual)/entriescore-js(-pure)/es|stable|actual|full/array(/virtual)/everycore-js(-pure)/es|stable|actual|full/array(/virtual)/fillcore-js(-pure)/es|stable|actual|full/array(/virtual)/filtercore-js(-pure)/es|stable|actual|full/array(/virtual)/findcore-js(-pure)/es|stable|actual|full/array(/virtual)/find-indexcore-js(-pure)/es|stable|actual|full/array(/virtual)/find-lastcore-js(-pure)/es|stable|actual|full/array(/virtual)/find-last-indexcore-js(-pure)/es|stable|actual|full/array(/virtual)/flatcore-js(-pure)/es|stable|actual|full/array(/virtual)/flat-mapcore-js(-pure)/es|stable|actual|full/array(/virtual)/for-eachcore-js(-pure)/es|stable|actual|full/array(/virtual)/includescore-js(-pure)/es|stable|actual|full/array(/virtual)/index-ofcore-js(-pure)/es|stable|actual|full/array(/virtual)/iteratorcore-js(-pure)/es|stable|actual|full/array(/virtual)/joincore-js(-pure)/es|stable|actual|full/array(/virtual)/keyscore-js(-pure)/es|stable|actual|full/array(/virtual)/last-index-ofcore-js(-pure)/es|stable|actual|full/array(/virtual)/mapcore-js(-pure)/es|stable|actual|full/array(/virtual)/pushcore-js(-pure)/es|stable|actual|full/array(/virtual)/reducecore-js(-pure)/es|stable|actual|full/array(/virtual)/reduce-rightcore-js(-pure)/es|stable|actual|full/array(/virtual)/reversecore-js(-pure)/es|stable|actual|full/array(/virtual)/slicecore-js(-pure)/es|stable|actual|full/array(/virtual)/somecore-js(-pure)/es|stable|actual|full/array(/virtual)/sortcore-js(-pure)/es|stable|actual|full/array(/virtual)/splicecore-js(-pure)/es|stable|actual|full/array(/virtual)/to-reversedcore-js(-pure)/es|stable|actual|full/array(/virtual)/to-sortedcore-js(-pure)/es|stable|actual|full/array(/virtual)/to-splicedcore-js(-pure)/es|stable|actual|full/array(/virtual)/unshiftcore-js(-pure)/es|stable|actual|full/array(/virtual)/valuescore-js(-pure)/es|stable|actual|full/array(/virtual)/with

Array.from(newSet([1,2,3,2,1]));// => [1, 2, 3]Array.from({0:1,1:2,2:3,length:3});// => [1, 2, 3]Array.from('123',Number);// => [1, 2, 3]Array.from('123',it=>it**2);// => [1, 4, 9]Array.of(1);// => [1]Array.of(1,2,3);// => [1, 2, 3]letarray=['a','b','c'];for(letvalueofarray)console.log(value);// => 'a', 'b', 'c'for(letvalueofarray.values())console.log(value);// => 'a', 'b', 'c'for(letkeyofarray.keys())console.log(key);// => 0, 1, 2for(let[key,value]ofarray.entries()){console.log(key);// => 0, 1, 2console.log(value);// => 'a', 'b', 'c'}functionisOdd(value){returnvalue%2;}[4,8,15,16,23,42].find(isOdd);// => 15[4,8,15,16,23,42].findIndex(isOdd);// => 2[1,2,3,4].findLast(isOdd);// => 3[1,2,3,4].findLastIndex(isOdd);// => 2Array(5).fill(42);// => [42, 42, 42, 42, 42][1,2,3,4,5].copyWithin(0,3);// => [4, 5, 3, 4, 5][1,2,3].includes(2);// => true[1,2,3].includes(4);// => false[1,2,3].includes(2,2);// => false[NaN].indexOf(NaN);// => -1[NaN].includes(NaN);// => trueArray(1).indexOf(undefined);// => -1Array(1).includes(undefined);// => true[1,[2,3],[4,5]].flat();// => [1, 2, 3, 4, 5][1,[2,[3,[4]]],5].flat();// => [1, 2, [3, [4]], 5][1,[2,[3,[4]]],5].flat(3);// => [1, 2, 3, 4, 5][{a:1,b:2},{a:3,b:4},{a:5,b:6}].flatMap(it=>[it.a,it.b]);// => [1, 2, 3, 4, 5, 6][1,2,3].at(1);// => 2[1,2,3].at(-1);// => 3constsequence=[1,2,3];sequence.toReversed();// => [3, 2, 1]sequence;// => [1, 2, 3]constinitialArray=[1,2,3,4];initialArray.toSpliced(1,2,5,6,7);// => [1, 5, 6, 7, 4]initialArray;// => [1, 2, 3, 4]constoutOfOrder=[3,1,2];outOfOrder.toSorted();// => [1, 2, 3]outOfOrder;// => [3, 1, 2]constcorrectionNeeded=[1,1,3];correctionNeeded.with(1,2);// => [1, 2, 3]correctionNeeded;// => [1, 1, 3]

awaitArray.fromAsync((asyncfunction*(){yield*[1,2,3];})(),i=>i**2);// => [1, 4, 9]

ECMAScript: Iterator⬆

classIterator{staticfrom(iterable:Iterable<any>|Iterator<any>):Iterator<any>;drop(limit:uint):Iterator<any>;every(callbackfn:(value:any,counter:uint)=>boolean):boolean;filter(callbackfn:(value:any,counter:uint)=>boolean):Iterator<any>;find(callbackfn:(value:any,counter:uint)=>boolean)):any;flatMap(callbackfn:(value:any,counter:uint)=>Iterable<any>|Iterator<any>):Iterator<any>;forEach(callbackfn:(value:any,counter:uint)=>void):void;map(callbackfn:(value:any,counter:uint)=>any):Iterator<any>;reduce(callbackfn:(memo:any,value:any,counter:uint)=>any,initialValue:any):any;some(callbackfn:(value:any,counter:uint)=>boolean):boolean;take(limit:uint):Iterator<any>;toArray():Array<any>;  @@dispose():undefined;  @@toStringTag:'Iterator'}

core-js(-pure)/es|stable|actual|full/iteratorcore-js(-pure)/es|stable|actual|full/iterator/disposecore-js(-pure)/es|stable|actual|full/iterator/dropcore-js(-pure)/es|stable|actual|full/iterator/everycore-js(-pure)/es|stable|actual|full/iterator/filtercore-js(-pure)/es|stable|actual|full/iterator/findcore-js(-pure)/es|stable|actual|full/iterator/flat-mapcore-js(-pure)/es|stable|actual|full/iterator/for-eachcore-js(-pure)/es|stable|actual|full/iterator/fromcore-js(-pure)/es|stable|actual|full/iterator/mapcore-js(-pure)/es|stable|actual|full/iterator/reducecore-js(-pure)/es|stable|actual|full/iterator/somecore-js(-pure)/es|stable|actual|full/iterator/takecore-js(-pure)/es|stable|actual|full/iterator/to-array

[1,2,3,4,5,6,7].values().drop(1).take(5).filter(it=>it%2).map(it=>it**2).toArray();// => [9, 25]Iterator.from({next:()=>({done:Math.random()>0.9,value:Math.random()*10|0}),}).toArray();// => [7, 6, 3, 0, 2, 8]

Warning

• For preventing prototype pollution, in thepure version, new%IteratorPrototype% methods are not added to the real%IteratorPrototype%, they are available only on wrappers - instead of[].values().map(fn) useIterator.from([]).map(fn).

ECMAScript: String and RegExp⬆

classString{staticfromCodePoint(...codePoints:Array<number>):string;staticraw({raw:Array<string>}, ...substitutions:Array<string>):string;at(index:int):string;includes(searchString:string,position?:number):boolean;startsWith(searchString:string,position?:number):boolean;endsWith(searchString:string,position?:number):boolean;repeat(count:number):string;padStart(length:number,fillStr?:string=' '):string;padEnd(length:number,fillStr?:string=' '):string;codePointAt(pos:number):number|void;match(template:any):any;// ES2015+ fix for support @@matchmatchAll(regexp:RegExp):Iterator;replace(template:any,replacer:any):any;// ES2015+ fix for support @@replacereplaceAll(searchValue:string|RegExp,replaceString:string|(searchValue,index,this)=>string):string;search(template:any):any;// ES2015+ fix for support @@searchsplit(template:any,limit?:int):Array<string>;;// ES2015+ fix for support @@split, some fixes for old enginestrim():string;trimLeft():string;trimRight():string;trimStart():string;trimEnd():string;isWellFormed():boolean;toWellFormed():string;anchor(name:string):string;big():string;blink():string;bold():string;fixed():string;fontcolor(color:string):string;fontsize(size:any):string;italics():string;link(url:string):string;small():string;strike():string;sub():string;substr(start:int,length?:int):string;sup():string;  @@iterator():Iterator<characters>;}classRegExp{// support of sticky (`y`) flag, dotAll (`s`) flag, named capture groups, can alter flagsconstructor(pattern:RegExp|string,flags?:string):RegExp;staticescape(value:string):stringexec():Array<string|undefined>|null;// IE8 fixestest(string:string):boolean;// delegation to `.exec`toString():string;// ES2015+ fix - generic  @@match(string:string):Array|null;  @@matchAll(string:string):Iterator;  @@replace(string:string,replaceValue:Function|string):string;  @@search(string:string):number;  @@split(string:string,limit:number):Array<string>;readonlyattributedotAll:boolean;// IE9+readonlyattributeflags:string;// IE9+readonlyattributesticky:boolean;// IE9+}functionescape(string:string):string;functionunescape(string:string):string;

core-js(-pure)/es|stable|actual|full/stringcore-js(-pure)/es|stable|actual|full/string/from-code-pointcore-js(-pure)/es|stable|actual|full/string/rawcore-js/es|stable|actual|full/string/matchcore-js/es|stable|actual|full/string/replacecore-js/es|stable|actual|full/string/searchcore-js/es|stable|actual|full/string/splitcore-js(-pure)/es|stable|actual/string(/virtual)/atcore-js(-pure)/es|stable|actual|full/string(/virtual)/code-point-atcore-js(-pure)/es|stable|actual|full/string(/virtual)/ends-withcore-js(-pure)/es|stable|actual|full/string(/virtual)/includescore-js(-pure)/es|stable|actual|full/string(/virtual)/starts-withcore-js(-pure)/es|stable|actual|full/string(/virtual)/match-allcore-js(-pure)/es|stable|actual|full/string(/virtual)/pad-startcore-js(-pure)/es|stable|actual|full/string(/virtual)/pad-endcore-js(-pure)/es|stable|actual|full/string(/virtual)/repeatcore-js(-pure)/es|stable|actual|full/string(/virtual)/replace-allcore-js(-pure)/es|stable|actual|full/string(/virtual)/trimcore-js(-pure)/es|stable|actual|full/string(/virtual)/trim-startcore-js(-pure)/es|stable|actual|full/string(/virtual)/trim-endcore-js(-pure)/es|stable|actual|full/string(/virtual)/trim-leftcore-js(-pure)/es|stable|actual|full/string(/virtual)/trim-rightcore-js(-pure)/es|stable|actual|full/string(/virtual)/is-well-formedcore-js(-pure)/es|stable|actual|full/string(/virtual)/to-well-formedcore-js(-pure)/es|stable|actual|full/string(/virtual)/anchorcore-js(-pure)/es|stable|actual|full/string(/virtual)/bigcore-js(-pure)/es|stable|actual|full/string(/virtual)/blinkcore-js(-pure)/es|stable|actual|full/string(/virtual)/boldcore-js(-pure)/es|stable|actual|full/string(/virtual)/fixedcore-js(-pure)/es|stable|actual|full/string(/virtual)/fontcolorcore-js(-pure)/es|stable|actual|full/string(/virtual)/fontsizecore-js(-pure)/es|stable|actual|full/string(/virtual)/italicscore-js(-pure)/es|stable|actual|full/string(/virtual)/linkcore-js(-pure)/es|stable|actual|full/string(/virtual)/smallcore-js(-pure)/es|stable|actual|full/string(/virtual)/strikecore-js(-pure)/es|stable|actual|full/string(/virtual)/subcore-js(-pure)/es|stable|actual|full/string(/virtual)/substrcore-js(-pure)/es|stable|actual|full/string(/virtual)/supcore-js(-pure)/es|stable|actual|full/string(/virtual)/iteratorcore-js/es|stable|actual|full/regexpcore-js/es|stable|actual|full/regexp/constructorcore-js(-pure)/es|stable|actual|full/regexp/escapecore-js/es|stable|actual|full/regexp/dot-allcore-js(-pure)/es|stable|actual|full/regexp/flagscore-js/es|stable|actual|full/regexp/stickycore-js/es|stable|actual|full/regexp/testcore-js/es|stable|actual|full/regexp/to-stringcore-js/es|stable|actual|full/escapecore-js/es|stable|actual|full/unescape

for(letvalueof'a𠮷b'){console.log(value);// => 'a', '𠮷', 'b'}'foobarbaz'.includes('bar');// => true'foobarbaz'.includes('bar',4);// => false'foobarbaz'.startsWith('foo');// => true'foobarbaz'.startsWith('bar',3);// => true'foobarbaz'.endsWith('baz');// => true'foobarbaz'.endsWith('bar',6);// => true'string'.repeat(3);// => 'stringstringstring''hello'.padStart(10);// => '     hello''hello'.padStart(10,'1234');// => '12341hello''hello'.padEnd(10);// => 'hello     ''hello'.padEnd(10,'1234');// => 'hello12341''𠮷'.codePointAt(0);// => 134071String.fromCodePoint(97,134071,98);// => 'a𠮷b'letname='Bob';String.raw`Hi\n${name}!`;// => 'Hi\\nBob!' (ES2015 template string syntax)String.raw({raw:'test'},0,1,2);// => 't0e1s2t''foo'.bold();// => '<b>foo</b>''bar'.anchor('a"b');// => '<a name="a&quot;b">bar</a>''baz'.link('https://example.com');// => '<a href="https://example.com">baz</a>'RegExp('.','s').test('\n');// => trueRegExp('.','s').dotAll;// => trueRegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)').exec('foo:abc,bar:def').groups;// => { foo: 'abc', bar: 'def' }'foo:abc,bar:def'.replace(RegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)'),'$<bar>,$<foo>');// => 'def,abc'// eslint-disable-next-line regexp/no-useless-flag -- exampleRegExp(/./g,'m');// => /./m/foo/.flags;// => ''/foo/gi.flags;// => 'gi'RegExp('foo','y').sticky;// => trueconsttext='First line\nSecond line';constregex=RegExp('(?<index>\\S+) line\\n?','y');regex.exec(text).groups.index;// => 'First'regex.exec(text).groups.index;// => 'Second'regex.exec(text);// => null'foo'.match({[Symbol.match]:()=>1});// => 1'foo'.replace({[Symbol.replace]:()=>2});// => 2'foo'.search({[Symbol.search]:()=>3});// => 3'foo'.split({[Symbol.split]:()=>4});// => 4RegExp.prototype.toString.call({source:'foo',flags:'bar'});// => '/foo/bar''   hello   '.trimLeft();// => 'hello   ''   hello   '.trimRight();// => '   hello''   hello   '.trimStart();// => 'hello   ''   hello   '.trimEnd();// => '   hello'for(let{groups:{ number, letter}}of'1111a2b3cccc'.matchAll(RegExp('(?<number>\\d)(?<letter>\\D)','g'))){console.log(number,letter);// => 1 a, 2 b, 3 c}'Test abc test test abc test.'.replaceAll('abc','foo');// -> 'Test foo test test foo test.''abc'.at(1);// => 'b''abc'.at(-1);// => 'c''a💩b'.isWellFormed();// => true'a\uD83Db'.isWellFormed();// => false'a💩b'.toWellFormed();// => 'a💩b''a\uD83Db'.toWellFormed();// => 'a�b'

console.log(RegExp.escape('10$'));// => '\\x310\\$'console.log(RegExp.escape('abcdefg_123456'));// => '\\x61bcdefg_123456'console.log(RegExp.escape('Привет'));// => 'Привет'console.log(RegExp.escape('(){}[]|,.?*+-^$=<>\\/#&!%:;@~\'"`'));// => '\\(\\)\\{\\}\\[\\]\\|\\x2c\\.\\?\\*\\+\\x2d\\^\\$\\x3d\\x3c\\x3e\\\\\\/\\x23\\x26\\x21\\x25\\x3a\\x3b\\x40\\x7e\\x27\\x22\\x60'console.log(RegExp.escape('\u0009\u000A\u000B\u000C\u000D\u0020\u00A0\u1680\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028\u2029\uFEFF'));// => '\\\t\\\n\\\v\\\f\\\r\\x20\\xa0\\u1680\\u2000\\u2001\\u2002\\u2003\\u2004\\u2005\\u2006\\u2007\\u2008\\u2009\\u200a\\u202f\\u205f\\u3000\\u2028\\u2029\\ufeff'console.log(RegExp.escape('💩'));// => '💩'console.log(RegExp.escape('\uD83D'));// => '\\ud83d'

ECMAScript: Number⬆

Number('0b1010101');// => 85Number('0o7654321');// => 2054353

classNumber{constructor(value:any):number;toExponential(digits:number):string;toFixed(digits:number):string;toPrecision(precision:number):string;staticisFinite(number:any):boolean;staticisNaN(number:any):boolean;staticisInteger(number:any):boolean;staticisSafeInteger(number:any):boolean;staticparseFloat(string:string):number;staticparseInt(string:string,radix?:number=10):number;staticEPSILON:number;staticMAX_SAFE_INTEGER:number;staticMIN_SAFE_INTEGER:number;}functionparseFloat(string:string):number;functionparseInt(string:string,radix?:number=10):number;

core-js(-pure)/es|stable|actual|full/numbercore-js(-pure)/es|stable|actual|full/number/constructorcore-js(-pure)/es|stable|actual|full/number/is-finitecore-js(-pure)/es|stable|actual|full/number/is-nancore-js(-pure)/es|stable|actual|full/number/is-integercore-js(-pure)/es|stable|actual|full/number/is-safe-integercore-js(-pure)/es|stable|actual|full/number/parse-floatcore-js(-pure)/es|stable|actual|full/number/parse-intcore-js(-pure)/es|stable|actual|full/number/epsiloncore-js(-pure)/es|stable|actual|full/number/max-safe-integercore-js(-pure)/es|stable|actual|full/number/min-safe-integercore-js(-pure)/es|stable|actual|full/number(/virtual)/to-exponentialcore-js(-pure)/es|stable|actual|full/number(/virtual)/to-fixedcore-js(-pure)/es|stable|actual|full/number(/virtual)/to-precisioncore-js(-pure)/es|stable|actual|full/parse-floatcore-js(-pure)/es|stable|actual|full/parse-int

ECMAScript: Math⬆

namespaceMath{acosh(number:number): number;asinh(number:number): number;atanh(number:number): number;cbrt(number:number): number;clz32(number:number): number;cosh(number:number): number;expm1(number:number): number;fround(number:number): number;f16round(number: any): number;hypot(...args:Array<number>): number;imul(number1: number,number2: number): number;log1p(number:number): number;log10(number:number): number;log2(number:number): number;sign(number:number):1|-1|0|-0|NaN;sinh(number:number): number;tanh(number:number): number;trunc(number:number): number;}

core-js(-pure)/es|stable|actual|full/mathcore-js(-pure)/es|stable|actual|full/math/acoshcore-js(-pure)/es|stable|actual|full/math/asinhcore-js(-pure)/es|stable|actual|full/math/atanhcore-js(-pure)/es|stable|actual|full/math/cbrtcore-js(-pure)/es|stable|actual|full/math/clz32core-js(-pure)/es|stable|actual|full/math/coshcore-js(-pure)/es|stable|actual|full/math/expm1core-js(-pure)/es|stable|actual|full/math/froundcore-js(-pure)/es|stable|actual|full/math/f16roundcore-js(-pure)/es|stable|actual|full/math/hypotcore-js(-pure)/es|stable|actual|full/math/imulcore-js(-pure)/es|stable|actual|full/math/log1pcore-js(-pure)/es|stable|actual|full/math/log10core-js(-pure)/es|stable|actual|full/math/log2core-js(-pure)/es|stable|actual|full/math/signcore-js(-pure)/es|stable|actual|full/math/sinhcore-js(-pure)/es|stable|actual|full/math/tanhcore-js(-pure)/es|stable|actual|full/math/trunc

ECMAScript: Date⬆

classDate{getYear():int;setYear(year:int):number;toGMTString():string;toISOString():string;toJSON():string;toString():string;  @@toPrimitive(hint:'default'|'number'|'string'):string|number;staticnow():number;}

core-js/es|stable|actual|full/datecore-js/es|stable|actual|full/date/to-stringcore-js(-pure)/es|stable|actual|full/date/nowcore-js(-pure)/es|stable|actual|full/date/get-yearcore-js(-pure)/es|stable|actual|full/date/set-yearcore-js(-pure)/es|stable|actual|full/date/to-gmt-stringcore-js(-pure)/es|stable|actual|full/date/to-iso-stringcore-js(-pure)/es|stable|actual|full/date/to-jsoncore-js(-pure)/es|stable|actual|full/date/to-primitive

newDate(NaN).toString();// => 'Invalid Date'

ECMAScript: Promise⬆

classPromise{constructor(executor:(resolve:Function,reject:Function)=>void):Promise;then(onFulfilled:Function,onRejected:Function):Promise;catch(onRejected:Function):Promise;finally(onFinally:Function):Promise;staticall(iterable:Iterable):Promise;staticallSettled(iterable:Iterable):Promise;staticany(promises:Iterable):Promise;staticrace(iterable:Iterable):Promise;staticreject(r:any):Promise;staticresolve(x:any):Promise;statictry(callbackfn:Function, ...args?:Array<mixed>):Promise;staticwithResolvers():{promise:Promise,resolve:function,reject:function};}

core-js(-pure)/es|stable|actual|full/promisecore-js(-pure)/es|stable|actual|full/promise/all-settledcore-js(-pure)/es|stable|actual|full/promise/anycore-js(-pure)/es|stable|actual|full/promise/finallycore-js(-pure)/es|stable|actual|full/promise/trycore-js(-pure)/es|stable|actual|full/promise/with-resolvers

/* eslint-disable promise/prefer-await-to-callbacks -- example */functionsleepRandom(time){returnnewPromise((resolve,reject)=>{setTimeout(resolve,time*1e3,0|Math.random()*1e3);});}console.log('Run');// => RunsleepRandom(5).then(result=>{console.log(result);// => 869, after 5 sec.returnsleepRandom(10);}).then(result=>{console.log(result);// => 202, after 10 sec.}).then(()=>{console.log('immediately after');// => immediately afterthrownewError('Irror!');}).then(()=>{console.log('will not be displayed');}).catch(error=>console.log(error));// => => Error: Irror!

/* eslint-disable promise/prefer-await-to-callbacks -- example */Promise.resolve(42).then(x=>console.log(x));// => 42Promise.reject(42).catch(error=>console.log(error));// => 42Promise.resolve($.getJSON('/data.json'));// => ES promise

Promise.resolve(42).finally(()=>console.log('You will see it anyway'));Promise.reject(42).finally(()=>console.log('You will see it anyway'));

Promise.all(['foo',sleepRandom(5),sleepRandom(15),sleepRandom(10),// after 15 sec:]).then(x=>console.log(x));// => ['foo', 956, 85, 382]

/* eslint-disable promise/prefer-await-to-callbacks -- example */functiontimeLimit(promise,time){returnPromise.race([promise,newPromise((resolve,reject)=>{setTimeout(reject,time*1e3,newError(`Await >${time} sec`));})]);}timeLimit(sleepRandom(5),10).then(x=>console.log(x));// => 853, after 5 sec.timeLimit(sleepRandom(15),10).catch(error=>console.log(error));// Error: Await > 10 sec

Promise.allSettled([Promise.resolve(1),Promise.reject(2),Promise.resolve(3),]).then(console.log);// => [{ value: 1, status: 'fulfilled' }, { reason: 2, status: 'rejected' }, { value: 3, status: 'fulfilled' }]

Promise.any([Promise.resolve(1),Promise.reject(2),Promise.resolve(3),]).then(console.log);// => 1Promise.any([Promise.reject(1),Promise.reject(2),Promise.reject(3),]).catch(({ errors})=>console.log(errors));// => [1, 2, 3]

/* eslint-disable promise/prefer-await-to-callbacks -- example */Promise.try(()=>42).then(it=>console.log(`Promise, resolved as${it}`));Promise.try(()=>{thrownewError('42');}).catch(error=>console.log(`Promise, rejected as${error}`));Promise.try(async()=>42).then(it=>console.log(`Promise, resolved as${it}`));Promise.try(async()=>{thrownewError('42');}).catch(error=>console.log(`Promise, rejected as${error}`));Promise.try(it=>it,42).then(it=>console.log(`Promise, resolved as${it}`));

constd=Promise.withResolvers();d.resolve(42);d.promise.then(console.log);// => 42

letdelay=time=>newPromise(resolve=>setTimeout(resolve,time));asyncfunctionsleepRandom(time){awaitdelay(time*1e3);return0|Math.random()*1e3;}asyncfunctionsleepError(time,msg){awaitdelay(time*1e3);thrownewError(msg);}(async()=>{try{console.log('Run');// => Runconsole.log(awaitsleepRandom(5));// => 936, after 5 sec.let[a,b,c]=awaitPromise.all([sleepRandom(5),sleepRandom(15),sleepRandom(10),]);console.log(a,b,c);// => 210 445 71, after 15 sec.awaitsleepError(5,'Error!');console.log('Will not be displayed');}catch(error){console.log(error);// => Error: 'Error!', after 5 sec.}})();