# core-js **Repository Path**: mirrors_opencollective/core-js ## Basic Information - **Project Name**: core-js - **Description**: Standard Library - **Primary Language**: Unknown - **License**: MIT - **Default Branch**: master - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2020-09-25 - **Last Updated**: 2026-05-24 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README # core-js [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/zloirock/core-js?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![version](https://img.shields.io/npm/v/core-js.svg)](https://www.npmjs.com/package/core-js) [![npm downloads](https://img.shields.io/npm/dm/core-js.svg)](http://npm-stat.com/charts.html?package=core-js&author=&from=2014-11-18) [![Build Status](https://travis-ci.org/zloirock/core-js.svg)](https://travis-ci.org/zloirock/core-js) [![devDependency status](https://david-dm.org/zloirock/core-js/dev-status.svg)](https://david-dm.org/zloirock/core-js?type=dev) ## As advertising: the author is looking for a good job -) ## [core-js@3, babel and a look into the future](https://github.com/zloirock/core-js/tree/master/docs/2019-03-19-core-js-3-babel-and-a-look-into-the-future.md) ## Open Collective Sponsors [**Become a sponsor**](https://opencollective.com/core-js#sponsor) and get your logo with a link to your site on our README on GitHub and NPM. ## Patreon Sponsors [**Become a sponsor**](https://www.patreon.com/zloirock) and get your logo with a link to your site on our README on GitHub and NPM. --- **If you looking documentation for obsolete `core-js@2`, please, check [this branch](https://github.com/zloirock/core-js/tree/v2).** Modular standard library for JavaScript. Includes polyfills for [ECMAScript up to 2019](#ecmascript): [promises](#ecmascript-promise), [symbols](#ecmascript-symbol), [collections](#ecmascript-collections), iterators, [typed arrays](#ecmascript-typed-arrays), many other features, [ECMAScript proposals](#ecmascript-proposals), [some cross-platform WHATWG / W3C features and proposals](#web-standards) like [`URL`](#url-and-urlsearchparams). You can load only required features or use it without global namespace pollution. [*Example*](http://goo.gl/a2xexl): ```js import 'core-js'; // <- at the top of your entry point Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] [1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5] Promise.resolve(32).then(x => console.log(x)); // => 32 ``` *You can load only required features*: ```js import 'core-js/features/array/from'; // <- at the top of your entry point import 'core-js/features/array/flat'; // <- at the top of your entry point import 'core-js/features/set'; // <- at the top of your entry point import 'core-js/features/promise'; // <- at the top of your entry point Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] [1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5] Promise.resolve(32).then(x => console.log(x)); // => 32 ``` *Or use it without global namespace pollution*: ```js import from from 'core-js-pure/features/array/from'; import flat from 'core-js-pure/features/array/flat'; import Set from 'core-js-pure/features/set'; import Promise from 'core-js-pure/features/promise'; from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] flat([1, [2, 3], [4, [5]]], 2); // => [1, 2, 3, 4, 5] Promise.resolve(32).then(x => console.log(x)); // => 32 ``` ### Index - [Usage](#usage) - [Installation](#installation) - [CommonJS API](#commonjs-api) - [Babel](#babel) - [`@babel/polyfill`](#babelpolyfill) - [`@babel/preset-env`](#babelpreset-env) - [`@babel/runtime`](#babelruntime) - [Configurable level of aggressiveness](#configurable-level-of-aggressiveness) - [Custom build](#custom-build) - [Compatibility data](#compatibility-data) - [Supported engines](#supported-engines) - [Features](#features) - [ECMAScript](#ecmascript) - [ECMAScript: Object](#ecmascript-object) - [ECMAScript: Function](#ecmascript-function) - [ECMAScript: Array](#ecmascript-array) - [ECMAScript: String and RegExp](#ecmascript-string-and-regexp) - [ECMAScript: Number](#ecmascript-number) - [ECMAScript: Math](#ecmascript-math) - [ECMAScript: Date](#ecmascript-date) - [ECMAScript: Promise](#ecmascript-promise) - [ECMAScript: Symbol](#ecmascript-symbol) - [ECMAScript: Collections](#ecmascript-collections) - [ECMAScript: Typed Arrays](#ecmascript-typed-arrays) - [ECMAScript: Reflect](#ecmascript-reflect) - [ECMAScript proposals](#ecmascript-proposals) - [stage 4 proposals](#stage-4-proposals) - [stage 3 proposals](#stage-3-proposals) - [stage 2 proposals](#stage-2-proposals) - [stage 1 proposals](#stage-1-proposals) - [stage 0 proposals](#stage-0-proposals) - [pre-stage 0 proposals](#pre-stage-0-proposals) - [Web standards](#web-standards) - [`setTimeout` and `setInterval`](#settimeout-and-setinterval) - [`setImmediate`](#setimmediate) - [`queueMicrotask`](#queuemicrotask) - [`URL` and `URLSearchParams`](#url-and-urlsearchparams) - [iterable DOM collections](#iterable-dom-collections) - [Iteration helpers](#iteration-helpers) - [Missing polyfills](#missing-polyfills) - [Contributing](./CONTRIBUTING.md) - [Changelog](./CHANGELOG.md) ## Usage ### Installation: ``` // global version npm install --save core-js@3.0.0 // version without global namespace pollution npm install --save core-js-pure@3.0.0 // bundled global version npm install --save core-js-bundle@3.0.0 ``` Already bundled version of `core-js` [on CDN](https://unpkg.com/core-js-bundle@3.0.0) ([minified version](https://unpkg.com/core-js-bundle@3.0.0/minified.js)). ### CommonJS API You can import only reqired for you polyfills, like in examples at the top of `README.md`. Available CommonJS entry points for all polyfilled methods / constructors and namespaces. Just some examples: ```js // polyfill all `core-js` features: import "core-js"; // polyfill only stable `core-js` 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 ES proposals: import "core-js/features/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: import Set from "core-js-pure/features/set"; import Set from "core-js-pure/stable/set"; import Set from "core-js-pure/es/set"; // if you want to polyfill just required methods: import "core-js/features/set/intersection"; import "core-js/stable/queue-microtask"; import "core-js/es/array/from"; // polyfill reflect metadata proposal: import "core-js/proposals/reflect-metadata"; // polyfill all stage 2+ proposals: import "core-js/stage/2"; ``` ##### Caveats when using CommonJS API: * `modules` path is 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 use `core-js` with the extension of native objects, recommended load all `core-js` modules at the top of the entry point of your application, otherwise, you can have conflicts. * `core-js` is extremely modular and uses a lot of very tiny modules, because of that for usage in browsers bundle up `core-js` instead of usage loader for each file, otherwise, you will have hundreds of requests. #### CommonJS and prototype methods without global namespace pollution In the `pure` version, we can't pollute prototypes of native constructors. Because of that, prototype methods transformed into static methods like in examples above. But with transpilers, we can use one more trick - [bind operator and virtual methods](https://github.com/tc39/proposal-bind-operator). Special for that, available `/virtual/` entry points. Example: ```js import fill from 'core-js-pure/features/array/virtual/fill'; import findIndex from 'core-js-pure/features/array/virtual/find-index'; Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4 // or import { fill, findIndex } from 'core-js-pure/features/array/virtual'; Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4 ``` ### Babel `core-js` integrated with `babel` and is the base for polyfilling-related `babel` features: #### `@babel/polyfill` [`@babel/polyfill`](http://babeljs.io/docs/usage/polyfill) [**IS** just the import of stable `core-js` features and `regenerator-runtime`](https://github.com/babel/babel/blob/c8bb4500326700e7dc68ce8c4b90b6482c48d82f/packages/babel-polyfill/src/index.js) for generators and async functions, so if you load `@babel/polyfill` - you load the global version of `core-js` without ES proposals. Now it's deprecated in favour of separate inclusion of required parts of `core-js` and `regenerator-runtime` and, for preventing breaking changes, left on `core-js@2`. As a full equal of `@babel/polyfill`, you can use this: ```js import 'core-js/stable'; import 'regenerator-runtime/runtime'; ``` #### `@babel/preset-env` [`@babel/preset-env`](https://github.com/babel/babel/tree/master/packages/babel-preset-env) has `useBuiltIns` option, which optimizes work with global version of `core-js`. With `useBuiltIns` option, you should also set `corejs` option to used version of `core-js`, like `corejs: 3` or `corejs: '3.0'`. - `useBuiltIns: 'entry'` replaces imports of `core-js` to import only required for a target environment modules. So, for example, ```js import 'core-js/stable'; ``` with `chrome 71` target will be replaced just to: ```js 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"; ``` It works for all entry points of global version of `core-js` and their combinations, for example for ```js import 'core-js/es'; import 'core-js/proposals/set-methods'; import 'core-js/features/set/map'; ``` with `chrome 71` target you will have as a result: ```js 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"; ``` - `useBuiltIns: 'usage'` add at the top of each file import of polyfills for features used in this file and not supported by target environments, so for: ```js // first file: var set = new Set([1, 2, 3]); // second file: var array = Array.of(1, 2, 3); ``` if target contains an old environment like `IE 11` we will have something like: ```js // first file: import 'core-js/modules/es.array.iterator'; import 'core-js/modules/es.object.to-string'; import 'core-js/modules/es.set'; var set = new Set([1, 2, 3]); // second file: import 'core-js/modules/es.array.of'; var array = Array.of(1, 2, 3); ``` By default, `@babel/preset-env` with `useBuiltIns: 'usage'` option polyfill only stable features, but you can enable polyfilling of proposals by `proposals` option, as `corejs: { version: 3, proposals: true }`. #### `@babel/runtime` [`@babel/runtime`](http://babeljs.io/docs/plugins/transform-runtime/) with `corejs: 3` option simplifies work with `core-js-pure`. It automatically replaces usage of modern features from JS standard library to imports from the version of `core-js` without global namespace pollution, so instead of: ```js import from from 'core-js-pure/stable/array/from'; import flat from 'core-js-pure/stable/array/flat'; import Set from 'core-js-pure/stable/set'; import Promise from 'core-js-pure/stable/promise'; from(new Set([1, 2, 3, 2, 1])); flat([1, [2, 3], [4, [5]]], 2); Promise.resolve(32).then(x => console.log(x)); ``` you can write just: ```js Array.from(new Set([1, 2, 3, 2, 1])); [1, [2, 3], [4, [5]]].flat(2); Promise.resolve(32).then(x => console.log(x)); ``` By default, `@babel/runtime` polyfill only stable features, but like in `@babel/preset-env`, you can enable polyfilling of proposals by `proposals` option, as `corejs: { version: 3, proposals: true }`. ### Configurable level of aggressiveness By default, `core-js` set polyfills only when they required. That means that `core-js` check is a feature available and works correctly or not and if it has no problems, `core-js` use native implementation. But sometimes `core-js` feature detection could be too strict for your case. For example, `Promise` constructor requires the support of unhandled rejection tracking and `@@species`. Sometimes we could have inverse problem - knowingly broken environment with problems not covered by `core-js` feature detection. For those cases, we could redefine this behaviour for certain polyfills: ```js import configurator from 'core-js/configurator'; configurator({ useNative: ['Promise'], // polyfills will be used only if natives completely unavailable usePolyfill: ['Array.from', 'String.prototype.padEnd'], // polyfills will be used anyway useFeatureDetection: ['Map', 'Set'], // default behaviour }); import 'core-js'; ``` It does not work with some features. Also, if you change the default behaviour, even `core-js` internals may not work correctly. ### Custom build For some cases could be useful adding a blacklist of features or generation a polyfill for target engines. You could use [`core-js-builder`](/packages/core-js-builder) package for that. ### Compatibility data [`core-js-compat`](/packages/core-js-compat) package contains data about the necessity of `core-js` modules and API for getting a list of required `core-js` modules by `browserslist` query. ## Supported engines **Tested in:** - Chrome 26+ - Firefox 4+ - Safari 5+ - Opera 12+ - Internet Explorer 8+ (sure, IE8 with ES3 limitations; IE7- also should work, but no longer tested) - Edge - Android Browser 2.3+ - iOS Safari 5.1+ - PhantomJS 1.9+ - NodeJS 0.8+ ...and it doesn't mean `core-js` will not work in other engines, they just have not been tested. ## Features: [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure) ``` ### ECMAScript [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es ``` #### ECMAScript: Object Modules [`es.object.assign`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.assign.js), [`es.object.is`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.is.js), [`es.object.set-prototype-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.set-prototype-of.js), [`es.object.to-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.to-string.js), [`es.object.freeze`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.freeze.js), [`es.object.seal`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.seal.js), [`es.object.prevent-extensions`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.prevent-extensions.js), [`es.object.is-frozen`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.is-frozen.js), [`es.object.is-sealed`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.is-sealed.js), [`es.object.is-extensible`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.is-extensible.js), [`es.object.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.get-own-property-descriptor.js), [`es.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.get-own-property-descriptors.js), [`es.object.get-prototype-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.get-prototype-of.js), [`es.object.keys`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.keys.js), [`es.object.values`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.values.js), [`es.object.entries`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.entries.js), [`es.object.get-own-property-names`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.get-own-property-names.js) and [`es.object.from-entries`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.from-entries.js). Just ES5 features: [`es.object.create`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.create.js), [`es.object.define-property`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.define-property.js) and [`es.object.define-properties`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.es.object.define-properties.js). [ES2017 Annex B](https://tc39.github.io/ecma262/#sec-object.prototype.__defineGetter__) - modules [`es.object.define-setter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.define-setter.js), [`es.object.define-getter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.define-getter.js), [`es.object.lookup-setter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.lookup-setter.js) and [`es.object.lookup-getter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.object.lookup-getter.js) ```js class Object { 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; static assign(target: Object, ...sources: Array): Object; static create(prototype: Object | null, properties?: { [property: PropertyKey]: PropertyDescriptor }): Object; static defineProperties(object: Object, properties: { [property: PropertyKey]: PropertyDescriptor })): Object; static defineProperty(object: Object, property: PropertyKey, attributes: PropertyDescriptor): Object; static entries(object: Object): Array<[string, mixed]>; static freeze(object: any): any; static fromEntries(iterable: Iterable<[key, value]>): Object; static getOwnPropertyDescriptor(object: any, property: PropertyKey): PropertyDescriptor | void; static getOwnPropertyDescriptors(object: any): { [property: PropertyKey]: PropertyDescriptor }; static getOwnPropertyNames(object: any): Array; static getPrototypeOf(object: any): Object | null; static is(value1: any, value2: any): boolean; static isExtensible(object: any): boolean; static isFrozen(object: any): boolean; static isSealed(object: any): boolean; static keys(object: any): Array; static preventExtensions(object: any): any; static seal(object: any): any; static setPrototypeOf(target: any, prototype: Object | null): any; // required __proto__ - IE11+ static values(object: any): Array; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/object core-js(-pure)/es|stable|features/object/assign core-js(-pure)/es|stable|features/object/is core-js(-pure)/es|stable|features/object/set-prototype-of core-js(-pure)/es|stable|features/object/get-prototype-of core-js(-pure)/es|stable|features/object/create core-js(-pure)/es|stable|features/object/define-property core-js(-pure)/es|stable|features/object/define-properties core-js(-pure)/es|stable|features/object/get-own-property-descriptor core-js(-pure)/es|stable|features/object/get-own-property-descriptors core-js(-pure)/es|stable|features/object/keys core-js(-pure)/es|stable|features/object/values core-js(-pure)/es|stable|features/object/entries core-js(-pure)/es|stable|features/object/get-own-property-names core-js(-pure)/es|stable|features/object/freeze core-js(-pure)/es|stable|features/object/from-entries core-js(-pure)/es|stable|features/object/seal core-js(-pure)/es|stable|features/object/prevent-extensions core-js(-pure)/es|stable|features/object/is-frozen core-js(-pure)/es|stable|features/object/is-sealed core-js(-pure)/es|stable|features/object/is-extensible core-js/es|stable|features/object/to-string core-js(-pure)/es|stable|features/object/define-getter core-js(-pure)/es|stable|features/object/define-setter core-js(-pure)/es|stable|features/object/lookup-getter core-js(-pure)/es|stable|features/object/lookup-setter ``` [*Examples*](https://goo.gl/sqY5mD): ```js let foo = { q: 1, w: 2 }; let bar = { e: 3, r: 4 }; let baz = { 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); // => true Object.is(0, -0); // => false Object.is(42, 42); // => true Object.is(42, '42'); // => false function Parent() {} function Child() {} Object.setPrototypeOf(Child.prototype, Parent.prototype); new Child() instanceof Child; // => true new Child() instanceof Parent; // => true let object = { [Symbol.toStringTag]: 'Foo' }; '' + object; // => '[object Foo]' Object.keys('qwe'); // => ['0', '1', '2'] Object.getPrototypeOf('qwe') === String.prototype; // => true Object.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] of Object.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: let copy = Object.create(Object.getPrototypeOf(object), Object.getOwnPropertyDescriptors(object)); // Mixin: Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); const map = new Map([['a', 1], ['b', 2]]); Object.fromEntries(map); // => { a: 1, b: 2 } class Unit { constructor(id) { this.id = id; } toString() { return `unit${ this.id }`; } } const units = new Set([new Unit(101), new Unit(102)]); Object.fromEntries(units.entries()); // => { unit101: Unit { id: 101 }, unit102: Unit { id: 102 } } ``` #### ECMAScript: Function Modules [`es.function.name`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.function.name.js), [`es.function.has-instance`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.function.has-instance.js). Just ES5: [`es.function.bind`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.function.bind.js). ```js class Function { name: string; bind(thisArg: any, ...args: Array): Function; @@hasInstance(value: any): boolean; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js/es|stable|features/function core-js/es|stable|features/function/name core-js/es|stable|features/function/has-instance core-js/es|stable|features/function/bind core-js/es|stable|features/function/virtual/bind ``` [*Example*](http://goo.gl/zqu3Wp): ```js (function foo() {}).name // => 'foo' console.log.bind(console, 42)(43); // => 42 43 ``` #### ECMAScript: Array Modules [`es.array.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.from.js), [`es.array.is-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.is-array.js), [`es.array.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.of.js), [`es.array.copy-within`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.copy-within.js), [`es.array.fill`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.fill.js), [`es.array.find`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.find.js), [`es.array.find-index`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.find-index.js), [`es.array.iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.iterator.js), [`es.array.includes`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.includes.js), [`es.array.slice`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.slice.js), [`es.array.join`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.join.js), [`es.array.index-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.index-of.js), [`es.array.last-index-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.last-index-of.js), [`es.array.every`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.every.js), [`es.array.some`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.some.js), [`es.array.for-each`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.for-each.js), [`es.array.map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.map.js), [`es.array.filter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.filter.js), [`es.array.reduce`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.reduce.js), [`es.array.reduce-right`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.reduce-right.js), [`es.array.reverse`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.reverse.js), [`es.array.sort`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.sort.js), [`es.array.flat`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.flat.js), [`es.array.flat-map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.flat-map.js), [`es.array.unscopables.flat`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.unscopables.flat.js) and [`es.array.unscopables.flat-map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array.unscopables.flat-map.js) ```js class Array { concat(...args: Array): Array; // with adding support of @@isConcatSpreadable and @@species copyWithin(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; // with adding support of @@species find(callbackfn: (value: any, index: number, target: any) => boolean), thisArg?: any): any; findIndex(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): number; flat(depthArg?: number = 1): Array; flatMap(mapFn: (value: any, index: number, target: any) => any, thisArg: any): Array; 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; lastIndexOf(searchElement: any, from?: number): number; map(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Array; // with adding support of @@species 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 fix slice(start?: number, end?: number): Array; // with adding support of @@species splice(start?: number, deleteCount?: number, ...items: Array): Array; // with adding support of @@species some(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): boolean; sort(comparefn?: (a: any, b: any) => number): this; values(): Iterator; @@iterator(): Iterator; @@unscopables: { [newMethodNames: string]: true }; static from(items: Iterable | ArrayLike, mapFn?: (value: any, index: number) => any, thisArg?: any): Array; static isArray(value: any): boolean; static of(...args: Array): Array; } class Arguments { @@iterator(): Iterator; // available only in core-js methods } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/array core-js(-pure)/es|stable|features/array/from core-js(-pure)/es|stable|features/array/of core-js(-pure)/es|stable|features/array/is-array core-js(-pure)/es|stable|features/array/concat core-js(-pure)/es|stable|features/array/entries core-js(-pure)/es|stable|features/array/every core-js(-pure)/es|stable|features/array/copy-within core-js(-pure)/es|stable|features/array/fill core-js(-pure)/es|stable|features/array/filter core-js(-pure)/es|stable|features/array/find core-js(-pure)/es|stable|features/array/find-index core-js(-pure)/es|stable|features/array/flat core-js(-pure)/es|stable|features/array/flat-map core-js(-pure)/es|stable|features/array/for-each core-js(-pure)/es|stable|features/array/includes core-js(-pure)/es|stable|features/array/index-of core-js(-pure)/es|stable|features/array/iterator core-js(-pure)/es|stable|features/array/join core-js(-pure)/es|stable|features/array/keys core-js(-pure)/es|stable|features/array/last-index-of core-js(-pure)/es|stable|features/array/map core-js(-pure)/es|stable|features/array/reduce core-js(-pure)/es|stable|features/array/reduce-right core-js(-pure)/es|stable|features/array/reverse core-js(-pure)/es|stable|features/array/slice core-js(-pure)/es|stable|features/array/splice core-js(-pure)/es|stable|features/array/some core-js(-pure)/es|stable|features/array/sort core-js(-pure)/es|stable|features/array/values core-js(-pure)/es|stable|features/array/virtual/concat core-js(-pure)/es|stable|features/array/virtual/copy-within core-js(-pure)/es|stable|features/array/virtual/entries core-js(-pure)/es|stable|features/array/virtual/every core-js(-pure)/es|stable|features/array/virtual/fill core-js(-pure)/es|stable|features/array/virtual/filter core-js(-pure)/es|stable|features/array/virtual/find core-js(-pure)/es|stable|features/array/virtual/find-index core-js(-pure)/es|stable|features/array/virtual/flat core-js(-pure)/es|stable|features/array/virtual/flat-map core-js(-pure)/es|stable|features/array/virtual/for-each core-js(-pure)/es|stable|features/array/virtual/includes core-js(-pure)/es|stable|features/array/virtual/index-of core-js(-pure)/es|stable|features/array/virtual/iterator core-js(-pure)/es|stable|features/array/virtual/join core-js(-pure)/es|stable|features/array/virtual/keys core-js(-pure)/es|stable|features/array/virtual/last-index-of core-js(-pure)/es|stable|features/array/virtual/map core-js(-pure)/es|stable|features/array/virtual/reduce core-js(-pure)/es|stable|features/array/virtual/reduce-right core-js(-pure)/es|stable|features/array/virtual/reverse core-js(-pure)/es|stable|features/array/virtual/slice core-js(-pure)/es|stable|features/array/virtual/some core-js(-pure)/es|stable|features/array/virtual/sort core-js(-pure)/es|stable|features/array/virtual/splice core-js(-pure)/es|stable|features/array/virtual/values ``` [*Examples*](https://goo.gl/Tegvq4): ```js Array.from(new Set([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 * it); // => [1, 4, 9] Array.of(1); // => [1] Array.of(1, 2, 3); // => [1, 2, 3] let array = ['a', 'b', 'c']; for (let value of array) console.log(value); // => 'a', 'b', 'c' for (let value of array.values()) console.log(value); // => 'a', 'b', 'c' for (let key of array.keys()) console.log(key); // => 0, 1, 2 for (let [key, value] of array.entries()) { console.log(key); // => 0, 1, 2 console.log(value); // => 'a', 'b', 'c' } function isOdd(value) { return value % 2; } [4, 8, 15, 16, 23, 42].find(isOdd); // => 15 [4, 8, 15, 16, 23, 42].findIndex(isOdd); // => 2 [4, 8, 15, 16, 23, 42].find(isNaN); // => undefined [4, 8, 15, 16, 23, 42].findIndex(isNaN); // => -1 Array(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); // => true Array(1).indexOf(undefined); // => -1 Array(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] ``` #### ECMAScript: String and RegExp The main part of `String` features: modules [`es.string.from-code-point`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.from-code-point.js), [`es.string.raw`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.raw.js), [`es.string.iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.iterator.js), [`es.string.split`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.split.js), [`es.string.code-point-at`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.code-point-at.js), [`es.string.ends-with`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.ends-with.js), [`es.string.includes`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.includes.js), [`es.string.repeat`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.repeat.js), [`es.string.pad-start`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.pad-start.js), [`es.string.pad-end`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.pad-end.js), [`es.string.starts-with`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.starts-with.js), [`es.string.trim`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.trim.js), [`es.string.trim-start`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.trim-start.js), [`es.string.trim-end`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.trim-end.js). Adding support of well-known [symbols](#ecmascript-symbol) `@@match`, `@@replace`, `@@search` and `@@split` and direct `.exec` calls to related `String` methods, modules [`es.string.match`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.match.js), [`es.string.replace`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.replace.js), [`es.string.search`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.search.js) and [`es.string.split`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.split.js). Annex B HTML methods. Ugly, but it's also the part of the spec. Modules [`es.string.anchor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.anchor.js), [`es.string.big`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.big.js), [`es.string.blink`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.blink.js), [`es.string.bold`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.bold.js), [`es.string.fixed`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.fixed.js), [`es.string.fontcolor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.fontcolor.js), [`es.string.fontsize`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.fontsize.js), [`es.string.italics`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.italics.js), [`es.string.link`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.link.js), [`es.string.small`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.small.js), [`es.string.strike`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.strike.js), [`es.string.sub`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.sub.js) and [`es.string.sup`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.string.sup.js). `RegExp` features: modules [`es.regexp.constructor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.regexp.constructor.js) and [`es.regexp.flags`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.regexp.flags.js). ```js class String { static fromCodePoint(...codePoints: Array): string; static raw({ raw: Array }, ...substitutions: Array): string; split(separator: string, limit?: number): Array; 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 @@match replace(template: any, replacer: any): any; // ES2015+ fix for support @@replace search(template: any): any; // ES2015+ fix for support @@search split(template: any, limit: any): any; // ES2015+ fix for support @@split, some fixes for old engines trim(): string; trimLeft(): string; trimRight(): string; trimStart(): string; trimEnd(): 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; sup(): string; @@iterator(): Iterator; } class RegExp { constructor(pattern: RegExp | string, flags?: string): RegExp; // ES2015+ fix - can alter flags (IE9+) exec(): Array | null; // IE8 fixes toString(): string; // ES2015+ fix - generic @@match(string: string): Array | null; @@replace(string: string, replaceValue: Function | string): string; @@search(string: string): number; @@split(string: string, limit: number): Array; readonly attribute flags: string; // IE9+ } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/string core-js(-pure)/es|stable|features/string/from-code-point core-js(-pure)/es|stable|features/string/raw core-js(-pure)/es|stable|features/string/includes core-js(-pure)/es|stable|features/string/starts-with core-js(-pure)/es|stable|features/string/ends-with core-js(-pure)/es|stable|features/string/repeat core-js(-pure)/es|stable|features/string/pad-start core-js(-pure)/es|stable|features/string/pad-end core-js(-pure)/es|stable|features/string/code-point-at core-js(-pure)/es|stable|features/string/trim core-js(-pure)/es|stable|features/string/trim-start core-js(-pure)/es|stable|features/string/trim-end core-js(-pure)/es|stable|features/string/trim-left core-js(-pure)/es|stable|features/string/trim-right core-js(-pure)/es|stable|features/string/anchor core-js(-pure)/es|stable|features/string/big core-js(-pure)/es|stable|features/string/blink core-js(-pure)/es|stable|features/string/bold core-js(-pure)/es|stable|features/string/fixed core-js(-pure)/es|stable|features/string/fontcolor core-js(-pure)/es|stable|features/string/fontsize core-js(-pure)/es|stable|features/string/italics core-js(-pure)/es|stable|features/string/link core-js(-pure)/es|stable|features/string/small core-js(-pure)/es|stable|features/string/strike core-js(-pure)/es|stable|features/string/sub core-js(-pure)/es|stable|features/string/sup core-js(-pure)/es|stable|features/string/iterator core-js(-pure)/es|stable|features/string/virtual/includes core-js(-pure)/es|stable|features/string/virtual/starts-with core-js(-pure)/es|stable|features/string/virtual/ends-with core-js(-pure)/es|stable|features/string/virtual/repeat core-js(-pure)/es|stable|features/string/virtual/pad-start core-js(-pure)/es|stable|features/string/virtual/pad-end core-js(-pure)/es|stable|features/string/virtual/code-point-at core-js(-pure)/es|stable|features/string/virtual/trim core-js(-pure)/es|stable|features/string/virtual/trim-start core-js(-pure)/es|stable|features/string/virtual/trim-end core-js(-pure)/es|stable|features/string/virtual/trim-left core-js(-pure)/es|stable|features/string/virtual/trim-right core-js(-pure)/es|stable|features/string/virtual/anchor core-js(-pure)/es|stable|features/string/virtual/big core-js(-pure)/es|stable|features/string/virtual/blink core-js(-pure)/es|stable|features/string/virtual/bold core-js(-pure)/es|stable|features/string/virtual/fixed core-js(-pure)/es|stable|features/string/virtual/fontcolor core-js(-pure)/es|stable|features/string/virtual/fontsize core-js(-pure)/es|stable|features/string/virtual/italics core-js(-pure)/es|stable|features/string/virtual/link core-js(-pure)/es|stable|features/string/virtual/small core-js(-pure)/es|stable|features/string/virtual/strike core-js(-pure)/es|stable|features/string/virtual/sub core-js(-pure)/es|stable|features/string/virtual/sup core-js(-pure)/es|stable|features/string/virtual/iterator core-js/es|stable|features/regexp core-js/es|stable|features/regexp/constructor core-js(-pure)/es|stable|features/regexp/flags core-js/es|stable|features/regexp/to-string core-js/es|stable|features/regexp/match core-js/es|stable|features/regexp/replace core-js/es|stable|features/regexp/search core-js/es|stable|features/regexp/split ``` [*Examples*](https://goo.gl/DR1Q72): ```js for (let value of '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); // => 134071 String.fromCodePoint(97, 134071, 98); // => 'a𠮷b' let name = 'Bob'; String.raw`Hi\n${name}!`; // => 'Hi\\nBob!' (ES2015 template string syntax) String.raw({ raw: 'test' }, 0, 1, 2); // => 't0e1s2t' 'foo'.bold(); // => 'foo' 'bar'.anchor('a"b'); // => 'bar' 'baz'.link('http://example.com'); // => 'baz' RegExp(/./g, 'm'); // => /./m /foo/.flags; // => '' /foo/gim.flags; // => 'gim' 'foo'.match({ [Symbol.match]: () => 1 }); // => 1 'foo'.replace({ [Symbol.replace]: () => 2 }); // => 2 'foo'.search({ [Symbol.search]: () => 3 }); // => 3 'foo'.split({ [Symbol.split]: () => 4 }); // => 4 RegExp.prototype.toString.call({ source: 'foo', flags: 'bar' }); // => '/foo/bar' ' hello '.trimLeft(); // => 'hello ' ' hello '.trimRight(); // => ' hello' ' hello '.trimStart(); // => 'hello ' ' hello '.trimEnd(); // => ' hello' ``` #### ECMAScript: Number Module [`es.number.constructor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.constructor.js). `Number` constructor support binary and octal literals, [*example*](http://goo.gl/jRd6b3): ```js Number('0b1010101'); // => 85 Number('0o7654321'); // => 2054353 ``` Modules [`es.number.epsilon`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.epsilon.js), [`es.number.is-finite`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.is-finite.js), [`es.number.is-integer`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.is-integer.js), [`es.number.is-nan`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.is-nan.js), [`es.number.is-safe-integer`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.is-safe-integer.js), [`es.number.max-safe-integer`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.max-safe-integer.js), [`es.number.min-safe-integer`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.min-safe-integer.js), [`es.number.parse-float`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.parse-float.js), [`es.number.parse-int`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.parse-int.js), [`es.number.to-fixed`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.to-fixed.js), [`es.number.to-precision`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.number.to-precision.js), [`es.parse-int`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.parse-int.js), [`es.parse-float`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.parse-float.js). ```js class Number { constructor(value: any): number; toFixed(digits: number): string; toPrecision(precision: number): string; static isFinite(number: any): boolean; static isNaN(number: any): boolean; static isInteger(number: any): boolean; static isSafeInteger(number: any): boolean; static parseFloat(string: string): number; static parseInt(string: string, radix?: number = 10): number; static EPSILON: number; static MAX_SAFE_INTEGER: number; static MIN_SAFE_INTEGER: number; } function parseFloat(string: string): number; function parseInt(string: string, radix?: number = 10): number; ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/number core-js/es|stable|features/number/constructor core-js(-pure)/es|stable|features/number/is-finite core-js(-pure)/es|stable|features/number/is-nan core-js(-pure)/es|stable|features/number/is-integer core-js(-pure)/es|stable|features/number/is-safe-integer core-js(-pure)/es|stable|features/number/parse-float core-js(-pure)/es|stable|features/number/parse-int core-js(-pure)/es|stable|features/number/epsilon core-js(-pure)/es|stable|features/number/max-safe-integer core-js(-pure)/es|stable|features/number/min-safe-integer core-js(-pure)/es|stable|features/number/to-fixed core-js(-pure)/es|stable|features/number/to-precision core-js(-pure)/es|stable|features/parse-float core-js(-pure)/es|stable|features/parse-int ``` #### ECMAScript: Math Modules [`es.math.acosh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.acosh.js), [`es.math.asinh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.asinh.js), [`es.math.atanh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.atanh.js), [`es.math.cbrt`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.cbrt.js), [`es.math.clz32`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.clz32.js), [`es.math.cosh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.cosh.js), [`es.math.expm1`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.expm1.js), [`es.math.fround`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.fround.js), [`es.math.hypot`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.hypot.js), [`es.math.imul`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.imul.js), [`es.math.log10`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.log10.js), [`es.math.log1p`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.log1p.js), [`es.math.log2`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.log2.js), [`es.math.sign`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.sign.js), [`es.math.sinh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.sinh.js), [`es.math.tanh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.tanh.js), [`es.math.trunc`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.trunc.js). ```js namespace Math { 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; hypot(...args: Array): 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; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/math core-js(-pure)/es|stable|features/math/acosh core-js(-pure)/es|stable|features/math/asinh core-js(-pure)/es|stable|features/math/atanh core-js(-pure)/es|stable|features/math/cbrt core-js(-pure)/es|stable|features/math/clz32 core-js(-pure)/es|stable|features/math/cosh core-js(-pure)/es|stable|features/math/expm1 core-js(-pure)/es|stable|features/math/fround core-js(-pure)/es|stable|features/math/hypot core-js(-pure)/es|stable|features/math/imul core-js(-pure)/es|stable|features/math/log1p core-js(-pure)/es|stable|features/math/log10 core-js(-pure)/es|stable|features/math/log2 core-js(-pure)/es|stable|features/math/sign core-js(-pure)/es|stable|features/math/sinh core-js(-pure)/es|stable|features/math/tanh core-js(-pure)/es|stable|features/math/trunc ``` #### ECMAScript: Date Modules [`es.date.to-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.date.to-string.js), ES5 features with fixes: [`es.date.now`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.date.now.js), [`es.date.to-iso-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.date.to-iso-string.js), [`es.date.to-json`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.date.to-json.js) and [`es.date.to-primitive`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.date.to-primitive.js). ```js class Date { toISOString(): string; toJSON(): string; toString(): string; @@toPrimitive(hint: 'default' | 'number' | 'string'): string | number; static now(): number; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js/es|stable|features/date core-js/es|stable|features/date/to-string core-js(-pure)/es|stable|features/date/now core-js(-pure)/es|stable|features/date/to-iso-string core-js(-pure)/es|stable|features/date/to-json core-js(-pure)/es|stable|features/date/to-primitive ``` [*Example*](http://goo.gl/haeHLR): ```js new Date(NaN).toString(); // => 'Invalid Date' ``` #### ECMAScript: Promise Modules [`es.promise`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.promise.js) and [`es.promise.finally`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.promise.finally.js). ```js class Promise { constructor(executor: (resolve: Function, reject: Function) => void): Promise; then(onFulfilled: Function, onRejected: Function): Promise; catch(onRejected: Function): Promise; finally(onFinally: Function): Promise; static resolve(x: any): Promise; static reject(r: any): Promise; static all(iterable: Iterable): Promise; static race(iterable: Iterable): Promise; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/promise core-js(-pure)/es|stable|features/promise/finally ``` Basic [*example*](http://goo.gl/vGrtUC): ```js function sleepRandom(time) { return new Promise((resolve, reject) => { setTimeout(resolve, time * 1e3, 0 | Math.random() * 1e3); }); } console.log('Run'); // => Run sleepRandom(5).then(result => { console.log(result); // => 869, after 5 sec. return sleepRandom(10); }).then(result => { console.log(result); // => 202, after 10 sec. }).then(() => { console.log('immediately after'); // => immediately after throw Error('Irror!'); }).then(() => { console.log('will not be displayed'); }).catch(x => console.log(x)); // => => Error: Irror! ``` `Promise.resolve` and `Promise.reject` [*example*](http://goo.gl/vr8TN3): ```js Promise.resolve(42).then(x => console.log(x)); // => 42 Promise.reject(42).catch(x => console.log(x)); // => 42 Promise.resolve($.getJSON('/data.json')); // => ES promise ``` `Promise#finally` [*example*](https://goo.gl/AhyBbJ): ```js Promise.resolve(42).finally(() => console.log('You will see it anyway')); Promise.reject(42).finally(() => console.log('You will see it anyway')); ``` `Promise.all` [*example*](http://goo.gl/RdoDBZ): ```js Promise.all([ 'foo', sleepRandom(5), sleepRandom(15), sleepRandom(10) // after 15 sec: ]).then(x => console.log(x)); // => ['foo', 956, 85, 382] ``` `Promise.race` [*example*](http://goo.gl/L8ovkJ): ```js function timeLimit(promise, time) { return Promise.race([promise, new Promise((resolve, reject) => { setTimeout(reject, time * 1e3, Error('Await > ' + time + ' sec')); })]); } timeLimit(sleepRandom(5), 10).then(x => console.log(x)); // => 853, after 5 sec. timeLimit(sleepRandom(15), 10).catch(x => console.log(x)); // Error: Await > 10 sec ``` [Example](http://goo.gl/wnQS4j) with async functions: ```js let delay = time => new Promise(resolve => setTimeout(resolve, time)) async function sleepRandom(time) { await delay(time * 1e3); return 0 | Math.random() * 1e3; } async function sleepError(time, msg) { await delay(time * 1e3); throw Error(msg); } (async () => { try { console.log('Run'); // => Run console.log(await sleepRandom(5)); // => 936, after 5 sec. let [a, b, c] = await Promise.all([ sleepRandom(5), sleepRandom(15), sleepRandom(10) ]); console.log(a, b, c); // => 210 445 71, after 15 sec. await sleepError(5, 'Error!'); console.log('Will not be displayed'); } catch (e) { console.log(e); // => Error: 'Error!', after 5 sec. } })(); ``` ##### Unhandled rejection tracking In Node.js, like in native implementation, available events [`unhandledRejection`](https://nodejs.org/api/process.html#process_event_unhandledrejection) and [`rejectionHandled`](https://nodejs.org/api/process.html#process_event_rejectionhandled): ```js process.on('unhandledRejection', (reason, promise) => console.log('unhandled', reason, promise)); process.on('rejectionHandled', (promise) => console.log('handled', promise)); let promise = Promise.reject(42); // unhandled 42 [object Promise] setTimeout(() => promise.catch(() => {}), 1e3); // handled [object Promise] ``` In a browser on rejection, by default, you will see notify in the console, or you can add a custom handler and a handler on handling unhandled, [*example*](http://goo.gl/Wozskl): ```js window.addEventListener('unhandledrejection', e => console.log('unhandled', e.reason, e.promise)); window.addEventListener('rejectionhandled', e => console.log('handled', e.reason, e.promise)); // or window.onunhandledrejection = e => console.log('unhandled', e.reason, e.promise); window.onrejectionhandled = e => console.log('handled', e.reason, e.promise); let promise = Promise.reject(42); // => unhandled 42 [object Promise] setTimeout(() => promise.catch(() => {}), 1e3); // => handled 42 [object Promise] ``` #### ECMAScript: Symbol Modules [`es.symbol`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.js), [`es.symbol.async-iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.async-iterator.js), [`esnext.symbol.description`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.symbol.description.js), [`es.symbol.has-instance`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.has-instance.js), [`es.symbol.is-concat-spreadable`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.is-concat-spreadable.js), [`es.symbol.iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.iterator.js), [`es.symbol.match`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.match.js), [`es.symbol.replace`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.replace.js), [`es.symbol.search`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.search.js), [`es.symbol.species`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.species.js), [`es.symbol.split`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.split.js), [`es.symbol.to-primitive`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.to-primitive.js), [`es.symbol.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.to-string-tag.js), [`es.symbol.unscopables`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.symbol.unscopables.js), [`es.math.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.math.to-string-tag.js), [`es.json.to-string-tag`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.json.to-string-tag.js). ```js class Symbol { constructor(description?): symbol; readonly attribute description: string | void; static asyncIterator: @@asyncIterator; static hasInstance: @@hasInstance; static isConcatSpreadable: @@isConcatSpreadable; static iterator: @@iterator; static match: @@match; static replace: @@replace; static search: @@search; static species: @@species; static split: @@split; static toPrimitive: @@toPrimitive; static toStringTag: @@toStringTag; static unscopables: @@unscopables; static for(key: string): symbol; static keyFor(sym: symbol): string; static useSimple(): void; static useSetter(): void; } class Object { static getOwnPropertySymbols(object: any): Array; } ``` Also wrapped some methods for correct work with `Symbol` polyfill. ```js class Object { static create(prototype: Object | null, properties?: { [property: PropertyKey]: PropertyDescriptor }): Object; static defineProperties(object: Object, properties: { [property: PropertyKey]: PropertyDescriptor })): Object; static defineProperty(object: Object, property: PropertyKey, attributes: PropertyDescriptor): Object; static getOwnPropertyDescriptor(object: any, property: PropertyKey): PropertyDescriptor | void; static getOwnPropertyNames(object: any): Array; propertyIsEnumerable(key: PropertyKey): boolean; } namespace JSON { stringify(target: any, replacer?: Function | Array, space?: string | number): string | void; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/symbol core-js(-pure)/es|stable|features/symbol/async-iterator core-js/es|stable|features/symbol/description core-js(-pure)/es|stable|features/symbol/has-instance core-js(-pure)/es|stable|features/symbol/is-concat-spreadable core-js(-pure)/es|stable|features/symbol/iterator core-js(-pure)/es|stable|features/symbol/match core-js(-pure)/es|stable|features/symbol/replace core-js(-pure)/es|stable|features/symbol/search core-js(-pure)/es|stable|features/symbol/species core-js(-pure)/es|stable|features/symbol/split core-js(-pure)/es|stable|features/symbol/to-primitive core-js(-pure)/es|stable|features/symbol/to-string-tag core-js(-pure)/es|stable|features/symbol/unscopables core-js(-pure)/es|stable|features/symbol/for core-js(-pure)/es|stable|features/symbol/key-for core-js(-pure)/es|stable|features/object/get-own-property-symbols core-js(-pure)/es|stable|features/math/to-string-tag core-js(-pure)/es|stable|features/json/to-string-tag ``` [*Basic example*](http://goo.gl/BbvWFc): ```js let Person = (() => { let NAME = Symbol('name'); return class { constructor(name) { this[NAME] = name; } getName() { return this[NAME]; } } })(); let person = new Person('Vasya'); console.log(person.getName()); // => 'Vasya' console.log(person['name']); // => undefined console.log(person[Symbol('name')]); // => undefined, symbols are uniq for (let key in person) console.log(key); // => nothing, symbols are not enumerable ``` `Symbol.for` & `Symbol.keyFor` [*example*](http://goo.gl/0pdJjX): ```js let symbol = Symbol.for('key'); symbol === Symbol.for('key'); // true Symbol.keyFor(symbol); // 'key' ``` [*Example*](http://goo.gl/mKVOQJ) with methods for getting own object keys: ```js let object = { a: 1 }; Object.defineProperty(object, 'b', { value: 2 }); object[Symbol('c')] = 3; Object.keys(object); // => ['a'] Object.getOwnPropertyNames(object); // => ['a', 'b'] Object.getOwnPropertySymbols(object); // => [Symbol(c)] Reflect.ownKeys(object); // => ['a', 'b', Symbol(c)] ``` [*Symbol#description getter*](https://goo.gl/MWizfc): ```js Symbol('foo').description; // => 'foo' Symbol().description; // => undefined ``` ##### Caveats when using `Symbol` polyfill: * We can't add new primitive type, `Symbol` returns object. * `Symbol.for` and `Symbol.keyFor` can't be shimmed cross-realm. * By default, to hide the keys, `Symbol` polyfill defines setter in `Object.prototype`. For this reason, uncontrolled creation of symbols can cause memory leak and the `in` operator is not working correctly with `Symbol` polyfill: `Symbol() in {} // => true`. You can disable defining setters in `Object.prototype`. [Example](http://goo.gl/N5UD7J): ```js Symbol.useSimple(); let symbol1 = Symbol('symbol1'); let object1 = {}; object1[symbol1] = true; for (let key in object1) console.log(key); // => 'Symbol(symbol1)_t.qamkg9f3q', w/o native Symbol Symbol.useSetter(); let symbol2 = Symbol('symbol2'); let object2 = {}; object2[symbol2] = true; for (let key in object2) console.log(key); // nothing ``` * Currently, `core-js` not adds setters to `Object.prototype` for well-known symbols for correct work something like `Symbol.iterator in foo`. It can cause problems with their enumerability. * Some problems possible with environment exotic objects (for example, IE `localStorage`). #### ECMAScript: Collections `core-js` uses native collections in most case, just fixes methods / constructor, if it's required, and in old environment uses fast polyfill (O(1) lookup). #### Map Module [`es.map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.map.js). ```js class Map { constructor(iterable?: Iterable<[key, value]>): Map; clear(): void; delete(key: any): boolean; forEach(callbackfn: (value: any, key: any, target: any) => void, thisArg: any): void; get(key: any): any; has(key: any): boolean; set(key: any, val: any): this; values(): Iterator; keys(): Iterator; entries(): Iterator<[key, value]>; @@iterator(): Iterator<[key, value]>; readonly attribute size: number; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/map ``` [*Examples*](http://goo.gl/GWR7NI): ```js let array = [1]; let map = new Map([['a', 1], [42, 2]]); map.set(array, 3).set(true, 4); console.log(map.size); // => 4 console.log(map.has(array)); // => true console.log(map.has([1])); // => false console.log(map.get(array)); // => 3 map.forEach((val, key) => { console.log(val); // => 1, 2, 3, 4 console.log(key); // => 'a', 42, [1], true }); map.delete(array); console.log(map.size); // => 3 console.log(map.get(array)); // => undefined console.log(Array.from(map)); // => [['a', 1], [42, 2], [true, 4]] let map = new Map([['a', 1], ['b', 2], ['c', 3]]); for (let [key, value] of map) { console.log(key); // => 'a', 'b', 'c' console.log(value); // => 1, 2, 3 } for (let value of map.values()) console.log(value); // => 1, 2, 3 for (let key of map.keys()) console.log(key); // => 'a', 'b', 'c' for (let [key, value] of map.entries()) { console.log(key); // => 'a', 'b', 'c' console.log(value); // => 1, 2, 3 } ``` #### Set Module [`es.set`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.set.js). ```js class Set { constructor(iterable?: Iterable): Set; add(key: any): this; clear(): void; delete(key: any): boolean; forEach((value: any, key: any, target: any) => void, thisArg: any): void; has(key: any): boolean; values(): Iterator; keys(): Iterator; entries(): Iterator<[value, value]>; @@iterator(): Iterator; readonly attribute size: number; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/set ``` [*Examples*](http://goo.gl/bmhLwg): ```js let set = new Set(['a', 'b', 'a', 'c']); set.add('d').add('b').add('e'); console.log(set.size); // => 5 console.log(set.has('b')); // => true set.forEach(it => { console.log(it); // => 'a', 'b', 'c', 'd', 'e' }); set.delete('b'); console.log(set.size); // => 4 console.log(set.has('b')); // => false console.log(Array.from(set)); // => ['a', 'c', 'd', 'e'] let set = new Set([1, 2, 3, 2, 1]); for (let value of set) console.log(value); // => 1, 2, 3 for (let value of set.values()) console.log(value); // => 1, 2, 3 for (let key of set.keys()) console.log(key); // => 1, 2, 3 for (let [key, value] of set.entries()) { console.log(key); // => 1, 2, 3 console.log(value); // => 1, 2, 3 } ``` #### WeakMap Module [`es.weak-map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.weak-map.js). ```js class WeakMap { constructor(iterable?: Iterable<[key, value]>): WeakMap; delete(key: Object): boolean; get(key: Object): any; has(key: Object): boolean; set(key: Object, val: any): this; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/weak-map ``` [*Examples*](http://goo.gl/SILXyw): ```js let a = [1]; let b = [2]; let c = [3]; let weakmap = new WeakMap([[a, 1], [b, 2]]); weakmap.set(c, 3).set(b, 4); console.log(weakmap.has(a)); // => true console.log(weakmap.has([1])); // => false console.log(weakmap.get(a)); // => 1 weakmap.delete(a); console.log(weakmap.get(a)); // => undefined // Private properties store: let Person = (() => { let names = new WeakMap; return class { constructor(name) { names.set(this, name); } getName() { return names.get(this); } } })(); let person = new Person('Vasya'); console.log(person.getName()); // => 'Vasya' for (let key in person) console.log(key); // => only 'getName' ``` #### WeakSet Module [`es.weak-set`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.weak-set.js). ```js class WeakSet { constructor(iterable?: Iterable): WeakSet; add(key: Object): this; delete(key: Object): boolean; has(key: Object): boolean; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/weak-set ``` [*Examples*](http://goo.gl/TdFbEx): ```js let a = [1]; let b = [2]; let c = [3]; let weakset = new WeakSet([a, b, a]); weakset.add(c).add(b).add(c); console.log(weakset.has(b)); // => true console.log(weakset.has([2])); // => false weakset.delete(b); console.log(weakset.has(b)); // => false ``` ##### Caveats when using collections polyfill: * Weak-collections polyfill stores values as hidden properties of keys. It works correct and not leak in most cases. However, it is desirable to store a collection longer than its keys. #### ECMAScript: Typed Arrays Implementations and fixes for `ArrayBuffer`, `DataView`, Typed Arrays constructors, static and prototype methods. Typed arrays work only in environments with support descriptors (IE9+), `ArrayBuffer` and `DataView` should work anywhere. Modules [`es.array-buffer.constructor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array-buffer.constructor.js), [`es.array-buffer.is-view`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array-buffer.is-view.js), [`es.array-buffer.slice`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.array-buffer.slice.js), [`es.data-view`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.data-view.js), [`es.typed-array.int8-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.int8-array.js), [`es.typed-array.uint8-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.uint8-array.js), [`es.typed-array.uint8-clamped-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.uint8-clamped-array.js), [`es.typed-array.int16-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.int16-array.js), [`es.typed-array.uint16-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.uint16-array.js), [`es.typed-array.int32-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed.int32-array.js), [`es.typed-array.uint32-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.uint32-array.js), [`es.typed-array.float32-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.float32-array.js), [`es.typed-array.float64-array`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.float64-array.js), [`es.typed-array.copy-within`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.copy-within.js), [`es.typed-array.every`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.every.js), [`es.typed-array.fill`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.fill.js), [`es.typed-array.filter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.filter.js), [`es.typed-array.find`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.find.js), [`es.typed-array.find-index`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.find-index.js), [`es.typed-array.for-each`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.for-each.js), [`es.typed-array.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.from.js), [`es.typed-array.includes`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.includes.js), [`es.typed-array.index-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.index-of.js), [`es.typed-array.iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.iterator.js), [`es.typed-array.last-index-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.last-index-of.js), [`es.typed-array.map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.map.js), [`es.typed-array.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.of.js), [`es.typed-array.reduce`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.reduce.js), [`es.typed-array.reduce-right`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.reduce-right.js), [`es.typed-array.reverse`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.reverse.js), [`es.typed-array.set`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.set.js), [`es.typed-array.slice`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.slice.js), [`es.typed-array.some`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.some.js), [`es.typed-array.sort`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.sort.js), [`es.typed-array.subarray`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.subarray.js), [`es.typed-array.to-locale-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.to-locale-string.js) and [`es.typed-array.to-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.typed-array.to-string.js). ```js class ArrayBuffer { constructor(length: any): ArrayBuffer; slice(start: any, end: any): ArrayBuffer; readonly attribute byteLength: number; static isView(arg: any): boolean; } class DataView { constructor(buffer: ArrayBuffer, byteOffset?: number, byteLength?: number): DataView; getInt8(offset: any): int8; getUint8(offset: any): uint8 getInt16(offset: any, littleEndian?: boolean = false): int16; getUint16(offset: any, littleEndian?: boolean = false): uint16; getInt32(offset: any, littleEndian?: boolean = false): int32; getUint32(offset: any, littleEndian?: boolean = false): uint32; getFloat32(offset: any, littleEndian?: boolean = false): float32; getFloat64(offset: any, littleEndian?: boolean = false): float64; setInt8(offset: any, value: any): void; setUint8(offset: any, value: any): void; setInt16(offset: any, value: any, littleEndian?: boolean = false): void; setUint16(offset: any, value: any, littleEndian?: boolean = false): void; setInt32(offset: any, value: any, littleEndian?: boolean = false): void; setUint32(offset: any, value: any, littleEndian?: boolean = false): void; setFloat32(offset: any, value: any, littleEndian?: boolean = false): void; setFloat64(offset: any, value: any, littleEndian?: boolean = false): void; readonly attribute buffer: ArrayBuffer; readonly attribute byteLength: number; readonly attribute byteOffset: number; } class [ Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, Float32Array, Float64Array, ] { constructor(length: number): %TypedArray%; constructor(object: %TypedArray% | Iterable | ArrayLike): %TypedArray%; constructor(buffer: ArrayBuffer, byteOffset?: number, length?: number): %TypedArray%; copyWithin(target: number, start: number, end?: number): this; every(callbackfn: (value: number, index: number, target: any) => boolean, thisArg?: any): boolean; fill(value: number, start?: number, end?: number): this; filter(callbackfn: (value: number, index: number, target: any) => boolean, thisArg?: any): %TypedArray%; find(callbackfn: (value: number, index: number, target: any) => boolean), thisArg?: any): any; findIndex(callbackfn: (value: number, index: number, target: any) => boolean, thisArg?: any): number; forEach(callbackfn: (value: number, index: number, target: any) => void, thisArg?: any): void; includes(searchElement: any, from?: number): boolean; indexOf(searchElement: any, from?: number): number; join(separator: string = ','): string; lastIndexOf(searchElement: any, from?: number): number; map(mapFn: (value: number, index: number, target: any) => number, thisArg?: any): %TypedArray%; reduce(callbackfn: (memo: any, value: number, index: number, target: any) => any, initialValue?: any): any; reduceRight(callbackfn: (memo: any, value: number, index: number, target: any) => any, initialValue?: any): any; reverse(): this; set(array: ArrayLike, offset?: number): void; slice(start?: number, end?: number): %TypedArray%; some(callbackfn: (value: number, index: number, target: any) => boolean, thisArg?: any): boolean; sort(comparefn?: (a: number, b: number) => number): this; subarray(begin?: number, end?: number): %TypedArray%; toString(): string; toLocaleString(): string; values(): Iterator; keys(): Iterator; entries(): Iterator<[index, value]>; @@iterator(): Iterator; readonly attribute buffer: ArrayBuffer; readonly attribute byteLength: number; readonly attribute byteOffset: number; readonly attribute length: number; BYTES_PER_ELEMENT: number; static from(items: Iterable | ArrayLike, mapFn?: (value: any, index: number) => any, thisArg?: any): %TypedArray%; static of(...args: Array): %TypedArray%; static BYTES_PER_ELEMENT: number; } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js/es|stable|features/array-buffer core-js/es|stable|features/array-buffer/constructor core-js/es|stable|features/array-buffer/is-view core-js/es|stable|features/array-buffer/slice core-js/es|stable|features/data-view core-js/es|stable|features/typed-array core-js/es|stable|features/typed-array/int8-array core-js/es|stable|features/typed-array/uint8-array core-js/es|stable|features/typed-array/uint8-clamped-array core-js/es|stable|features/typed-array/int16-array core-js/es|stable|features/typed-array/uint16-array core-js/es|stable|features/typed-array/int32-array core-js/es|stable|features/typed-array/uint32-array core-js/es|stable|features/typed-array/float32-array core-js/es|stable|features/typed-array/float64-array core-js/es|stable|features/typed-array/copy-within core-js/es|stable|features/typed-array/entries core-js/es|stable|features/typed-array/every core-js/es|stable|features/typed-array/fill core-js/es|stable|features/typed-array/filter core-js/es|stable|features/typed-array/find core-js/es|stable|features/typed-array/find-index core-js/es|stable|features/typed-array/for-each core-js/es|stable|features/typed-array/from core-js/es|stable|features/typed-array/includes core-js/es|stable|features/typed-array/index-of core-js/es|stable|features/typed-array/iterator core-js/es|stable|features/typed-array/join core-js/es|stable|features/typed-array/keys core-js/es|stable|features/typed-array/last-index-of core-js/es|stable|features/typed-array/map core-js/es|stable|features/typed-array/of core-js/es|stable|features/typed-array/reduce core-js/es|stable|features/typed-array/reduce-right core-js/es|stable|features/typed-array/reverse core-js/es|stable|features/typed-array/set core-js/es|stable|features/typed-array/slice core-js/es|stable|features/typed-array/some core-js/es|stable|features/typed-array/sort core-js/es|stable|features/typed-array/subarray core-js/es|stable|features/typed-array/to-locale-string core-js/es|stable|features/typed-array/to-string core-js/es|stable|features/typed-array/values ``` [*Examples*](http://goo.gl/yla75z): ```js new Int32Array(4); // => [0, 0, 0, 0] new Uint8ClampedArray([1, 2, 3, 666]); // => [1, 2, 3, 255] new Float32Array(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] let buffer = new ArrayBuffer(8); let view = new DataView(buffer); view.setFloat64(0, 123.456, true); new Uint8Array(buffer.slice(4)); // => [47, 221, 94, 64] Int8Array.of(1, 1.5, 5.7, 745); // => [1, 1, 5, -23] Uint8Array.from([1, 1.5, 5.7, 745]); // => [1, 1, 5, 233] let typed = new Uint8Array([1, 2, 3]); let a = typed.slice(1); // => [2, 3] typed.buffer === a.buffer; // => false let b = typed.subarray(1); // => [2, 3] typed.buffer === b.buffer; // => true typed.filter(it => it % 2); // => [1, 3] typed.map(it => it * 1.5); // => [1, 3, 4] for (let value of typed) console.log(value); // => 1, 2, 3 for (let value of typed.values()) console.log(value); // => 1, 2, 3 for (let key of typed.keys()) console.log(key); // => 0, 1, 2 for (let [key, value] of typed.entries()) { console.log(key); // => 0, 1, 2 console.log(value); // => 1, 2, 3 } ``` ##### Caveats when using typed arrays polyfills: * Polyfills of Typed Arrays constructors work completely how should work by the spec, but because of internal usage of getters / setters on each instance, are slow and consumes significant memory. However, polyfills of Typed Arrays constructors required mainly for old IE, all modern engines have native Typed Arrays constructors and require only fixes of constructors and polyfills of methods. #### ECMAScript: Reflect Modules [`es.reflect.apply`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.apply.js), [`es.reflect.construct`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.construct.js), [`es.reflect.define-property`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.define-property.js), [`es.reflect.delete-property`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.delete-property.js), [`es.reflect.get`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.get.js), [`es.reflect.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.get-own-property-descriptor.js), [`es.reflect.get-prototype-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.get-prototype-of.js), [`es.reflect.has`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.has.js), [`es.reflect.is-extensible`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.is-extensible.js), [`es.reflect.own-keys`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.own-keys.js), [`es.reflect.prevent-extensions`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.prevent-extensions.js), [`es.reflect.set`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.set.js), [`es.reflect.set-prototype-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/es.reflect.set-prototype-of.js). ```js namespace Reflect { apply(target: Function, thisArgument: any, argumentsList: Array): any; construct(target: Function, argumentsList: Array, newTarget?: Function): Object; defineProperty(target: Object, propertyKey: PropertyKey, attributes: PropertyDescriptor): boolean; deleteProperty(target: Object, propertyKey: PropertyKey): boolean; get(target: Object, propertyKey: PropertyKey, receiver?: any): any; getOwnPropertyDescriptor(target: Object, propertyKey: PropertyKey): PropertyDescriptor | void; getPrototypeOf(target: Object): Object | null; has(target: Object, propertyKey: PropertyKey): boolean; isExtensible(target: Object): boolean; ownKeys(target: Object): Array; preventExtensions(target: Object): boolean; set(target: Object, propertyKey: PropertyKey, V: any, receiver?: any): boolean; setPrototypeOf(target: Object, proto: Object | null): boolean; // required __proto__ - IE11+ } ``` [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/es|stable|features/reflect core-js(-pure)/es|stable|features/reflect/apply core-js(-pure)/es|stable|features/reflect/construct core-js(-pure)/es|stable|features/reflect/define-property core-js(-pure)/es|stable|features/reflect/delete-property core-js(-pure)/es|stable|features/reflect/get core-js(-pure)/es|stable|features/reflect/get-own-property-descriptor core-js(-pure)/es|stable|features/reflect/get-prototype-of core-js(-pure)/es|stable|features/reflect/has core-js(-pure)/es|stable|features/reflect/is-extensible core-js(-pure)/es|stable|features/reflect/own-keys core-js(-pure)/es|stable|features/reflect/prevent-extensions core-js(-pure)/es|stable|features/reflect/set core-js(-pure)/es|stable|features/reflect/set-prototype-of ``` [*Examples*](http://goo.gl/gVT0cH): ```js let object = { a: 1 }; Object.defineProperty(object, 'b', { value: 2 }); object[Symbol('c')] = 3; Reflect.ownKeys(object); // => ['a', 'b', Symbol(c)] function C(a, b) { this.c = a + b; } let instance = Reflect.construct(C, [20, 22]); instance.c; // => 42 ``` ### ECMAScript proposals [The TC39 process.](https://tc39.github.io/process-document/) `core-js/stage/4` entry point contains only stage 4 proposals, `core-js/stage/3` - stage 3 and stage 4, etc. #### Stage 4 proposals [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/stage/4 ``` None. #### Stage 3 proposals [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/stage/3 ``` * `String#matchAll` [proposal](https://github.com/tc39/proposal-string-matchall) - module [`esnext.string.match-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.string.match-all.js) ```js class String { matchAll(regexp: RegExp): Iterator; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/string-match-all core-js(-pure)/features/string/match-all core-js(-pure)/features/string/virtual/match-all ``` [*Examples*](https://goo.gl/AxSqHT): ```js for (let [_, d, D] of '1111a2b3cccc'.matchAll(/(\d)(\D)/g)) { console.log(d, D); // => 1 a, 2 b, 3 c } ``` * `globalThis` [proposal](https://github.com/tc39/proposal-global) - module [`esnext.global-this`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.global-this.js). ```js let globalThis: Object; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/global-this core-js(-pure)/features/global-this ``` [*Examples*](https://goo.gl/LAifsc): ```js globalThis.Array === Array; // => true ``` #### Stage 2 proposals [*CommonJS entry points:*](#commonjs-api) ``` core-js(-pure)/stage/2 ``` * New `Set` methods [proposal](https://github.com/tc39/proposal-set-methods) - modules [`esnext.set.difference`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.difference.js), [`esnext.set.intersection`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.intersection.js), [`esnext.set.is-disjoint-from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.is-disjoint-from.js), [`esnext.set.is-subset-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.is-subset-of.js), [`esnext.set.is-superset-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.is-superset-of.js), [`esnext.set.symmetric-difference`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.symmetric-difference.js), [`esnext.set.union`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.union.js) ```js class Set { difference(iterable: Iterable): Set; intersection(iterable: Iterable): Set; isDisjointFrom(iterable: Iterable): boolean; isSubsetOf(iterable: Iterable): boolean; isSupersetOf(iterable: Iterable): boolean; symmetric-difference(iterable: Iterable): Set; union(iterable: Iterable): Set; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/set-methods core-js(-pure)/features/set/difference core-js(-pure)/features/set/intersection core-js(-pure)/features/set/is-disjoint-from core-js(-pure)/features/set/is-subset-of core-js(-pure)/features/set/is-superset-of core-js(-pure)/features/set/symmetric-difference core-js(-pure)/features/set/union ``` [*Examples*](https://goo.gl/QMQdaJ): ```js new Set([1, 2, 3]).union([3, 4, 5]); // => Set {1, 2, 3, 4, 5} new Set([1, 2, 3]).intersection([3, 4, 5]); // => Set {3} new Set([1, 2, 3]).difference([3, 4, 5]); // => Set {1, 2} new Set([1, 2, 3]).symmetricDifference([3, 4, 5]); // => Set {1, 2, 4, 5} new Set([1, 2, 3]).isDisjointFrom([4, 5, 6]); // => true new Set([1, 2, 3]).isSubsetOf([5, 4, 3, 2, 1]); // => true new Set([5, 4, 3, 2, 1]).isSupersetOf([1, 2, 3]); // => true ``` * `Promise.allSettled` [proposal](https://github.com/tc39/proposal-promise-allSettled) - module [`esnext.promise.all-settled`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.promise.all-settled.js) ```js class Promise { static allSettled(iterable): promise; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/promise-all-settled core-js(-pure)/features/promise/all-settled ``` [*Examples*](https://goo.gl/PXXLNJ): ```js 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' }] ``` #### Stage 1 proposals [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/stage/1 ``` * Getting last item from `Array` [proposal](https://github.com/keithamus/proposal-array-last) - modules [`esnext.array.last-item`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.array.last-item.js) and [`esnext.array.last-index`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.array.last-index.js) ```js class Array { attribute lastItem: any; readonly attribute lastIndex: uint; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/array-last core-js/features/array/last-item core-js/features/array/last-index ``` [*Examples*](https://goo.gl/2TmcMT): ```js [1, 2, 3].lastItem; // => 3 [1, 2, 3].lastIndex; // => 2 const array = [1, 2, 3]; array.lastItem = 4; array; // => [1, 2, 4] ``` * `String#replaceAll` [proposal](https://github.com/tc39/proposal-string-replace-all) - module [`esnext.string.replace-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.string.replace-all.js) ```js class String { replaceAll(searchValue: string | RegExp, replaceString: string): string; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/string-replace-all core-js/features/string/replace-all ``` [*Examples*](https://goo.gl/wUXNXN): ```js 'Test abc test test abc test.'.replaceAll('abc', 'foo'); // -> 'Test foo test test foo test.' ``` * `Promise.try` [proposal](https://github.com/tc39/proposal-promise-try) - module [`esnext.promise.try`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.promise.try.js) ```js class Promise { static try(callbackfn: Function): promise; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/promise-try core-js(-pure)/features/promise/try ``` [*Examples*](https://goo.gl/k5GGRo): ```js Promise.try(() => 42).then(it => console.log(`Promise, resolved as ${it}`)); Promise.try(() => { throw 42; }).catch(it => console.log(`Promise, rejected as ${it}`)); ``` * New collections methods proposals: - New `Set` and `Map` methods [proposal](https://github.com/tc39/proposal-collection-methods) - modules [`esnext.set.add-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.add-all.js), [`esnext.set.delete-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.delete-all.js), [`esnext.set.every`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.every.js), [`esnext.set.filter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.filter.js), [`esnext.set.find`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.find.js), [`esnext.set.join`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.join.js), [`esnext.set.map`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.map.js), [`esnext.set.reduce`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.reduce.js), [`esnext.set.some`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.some.js), [`esnext.map.delete-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.delete-all.js), [`esnext.map.every`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.every.js), [`esnext.map.filter`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.filter.js), [`esnext.map.find`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.find.js), [`esnext.map.find-key`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.find-key.js), [`esnext.map.group-by`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.group-by.js), [`esnext.map.includes`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.includes.js), [`esnext.map.key-by`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.key-by.js), [`esnext.map.key-of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.key-of.js), [`esnext.map.map-keys`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.map-keys.js), [`esnext.map.map-values`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.map-values.js), [`esnext.map.merge`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.merge.js), [`esnext.map.reduce`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.reduce.js), [`esnext.map.some`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.some.js), [`esnext.map.update`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.update.js), [`esnext.weak-set.add-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-set.add-all.js), [`esnext.weak-set.delete-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-set.delete-all.js), [`esnext.weak-map.delete-all`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-map.delete-all.js) - `.of` and `.from` methods on collection constructors [proposal](https://github.com/tc39/proposal-setmap-offrom) - modules [`esnext.set.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.of.js), [`esnext.set.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.set.from.js), [`esnext.map.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.of.js), [`esnext.map.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.map.from.js), [`esnext.weak-set.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-set.of.js), [`esnext.weak-set.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-set.from.js), [`esnext.weak-map.of`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-map.of.js), [`esnext.weak-map.from`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.weak-map.from.js) ```js class Set { static of(...args: Array): Set; static from(iterable: Iterable, mapFn?: (value: any, index: number) => any, thisArg?: any): Set; addAll(...args: Array): this; deleteAll(...args: Array): boolean; every(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean; filter(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): Set; find(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any; join(separator: string = ','): string; map(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): Set; reduce(callbackfn: (memo: any, value: any, key: any, target: any) => any, initialValue?: any): any; some(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean; } class Map { static groupBy(iterable: Iterable, callbackfn?: (value: any) => any): Map; static of(...args: Array<[key, value]>): Map; static from(iterable: Iterable, mapFn?: (value: any, index: number) => [key: any, value: any], thisArg?: any): Map; static keyBy(iterable: Iterable, callbackfn?: (value: any) => any): Map; deleteAll(...args: Array): boolean; every(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean; filter(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): Map; find(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any; findKey(callbackfn: (value: any, key: any, target: any) => boolean), thisArg?: any): any; includes(searchElement: any): boolean; keyOf(searchElement: any): any; mapKeys(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Map; mapValues(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Map; merge(...iterables: Array): this; reduce(callbackfn: (memo: any, value: any, key: any, target: any) => any, initialValue?: any): any; some(callbackfn: (value: any, key: any, target: any) => boolean, thisArg?: any): boolean; update(key: any, callbackfn: (value: any, key: any, target: any) => any, thunk?: (key: any, target: any) => any): this; } class WeakSet { static of(...args: Array): WeakSet; static from(iterable: Iterable, mapFn?: (value: any, index: number) => Object, thisArg?: any): WeakSet; addAll(...args: Array): this; deleteAll(...args: Array): boolean; } class WeakMap { static of(...args: Array<[key, value]>): WeakMap; static from(iterable: Iterable, mapFn?: (value: any, index: number) => [key: Object, value: any], thisArg?: any): WeakMap; deleteAll(...args: Array): boolean; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/collection-methods core-js/proposals/collection-of-from core-js(-pure)/features/set/add-all core-js(-pure)/features/set/delete-all core-js(-pure)/features/set/every core-js(-pure)/features/set/filter core-js(-pure)/features/set/find core-js(-pure)/features/set/from core-js(-pure)/features/set/join core-js(-pure)/features/set/map core-js(-pure)/features/set/of core-js(-pure)/features/set/reduce core-js(-pure)/features/set/some core-js(-pure)/features/map/delete-all core-js(-pure)/features/map/every core-js(-pure)/features/map/filter core-js(-pure)/features/map/find core-js(-pure)/features/map/find-key core-js(-pure)/features/map/from core-js(-pure)/features/map/group-by core-js(-pure)/features/map/includes core-js(-pure)/features/map/key-by core-js(-pure)/features/map/key-of core-js(-pure)/features/map/map-keys core-js(-pure)/features/map/map-values core-js(-pure)/features/map/merge core-js(-pure)/features/map/of core-js(-pure)/features/map/reduce core-js(-pure)/features/map/some core-js(-pure)/features/map/update core-js(-pure)/features/weak-set/add-all core-js(-pure)/features/weak-set/delete-all core-js(-pure)/features/weak-set/of core-js(-pure)/features/weak-set/from core-js(-pure)/features/weak-map/delete-all core-js(-pure)/features/weak-map/of core-js(-pure)/features/weak-map/from ``` [*Examples*](https://goo.gl/mSC7eU): ```js Set.of(1, 2, 3, 2, 1); // => Set {1, 2, 3} Map.from([[1, 2], [3, 4]], ([key, value]) => [key ** 2, value ** 2]); // => Map {1: 4, 9: 16} ``` * `compositeKey` and `compositeSymbol` methods [proposal](https://github.com/tc39/proposal-richer-keys/tree/master/compositeKey) - modules [`esnext.composite-key`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.composite-key.js) and [`esnext.composite-symbol`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.composite-symbol.js) ```js function compositeKey(...args: Array): object; function compositeSymbol(...args: Array): symbol; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/keys-composition core-js(-pure)/features/composite-key core-js(-pure)/features/composite-symbol ``` [*Examples*](https://goo.gl/2oPAH7): ```js // returns a symbol const symbol = compositeSymbol({}); console.log(typeof symbol); // => 'symbol' // works the same, but returns a plain frozen object without a prototype const key = compositeKey({}); console.log(typeof key); // => 'object' console.log({}.toString.call(key)); // => '[object Object]' console.log(Object.getPrototypeOf(key)); // => null console.log(Object.isFrozen(key)); // => true const a = ['a']; const b = ['b']; const c = ['c']; console.log(compositeSymbol(a) === compositeSymbol(a)); // => true console.log(compositeSymbol(a) !== compositeSymbol(['a'])); // => true console.log(compositeSymbol(a, 1) === compositeSymbol(a, 1)); // => true console.log(compositeSymbol(a, b) !== compositeSymbol(b, a)); // => true console.log(compositeSymbol(a, b, c) === compositeSymbol(a, b, c)); // => true console.log(compositeSymbol(1, a) === compositeSymbol(1, a)); // => true console.log(compositeSymbol(1, a, 2, b) === compositeSymbol(1, a, 2, b)); // => true console.log(compositeSymbol(a, a) === compositeSymbol(a, a)); // => true ``` * `Observable` [proposal](https://github.com/zenparsing/es-observable) - modules [`esnext.observable`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.observable.js) and [`esnext.symbol.observable`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.symbol.observable.js) ```js class Observable { constructor(subscriber: Function): Observable; subscribe(observer: Function | { next?: Function, error?: Function, complete?: Function }): Subscription; @@observable(): this; static of(...items: Aray): Observable; static from(x: Observable | Iterable): Observable; static readonly attribute @@species: this; } class Symbol { static observable: @@observable; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/observable core-js(-pure)/features/observable core-js(-pure)/features/symbol/observable ``` [*Examples*](http://goo.gl/1LDywi): ```js new Observable(observer => { observer.next('hello'); observer.next('world'); observer.complete(); }).subscribe({ next(it) { console.log(it); }, complete() { console.log('!'); } }); ``` * `Math` extensions [proposal](https://github.com/rwaldron/proposal-math-extensions) - modules [`esnext.math.clamp`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.clamp.js), [`esnext.math.DEG_PER_RAD`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.DEG_PER_RAD.js), [`esnext.math.degrees`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.degrees.js), [`esnext.math.fscale`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.fscale.js), [`esnext.math.RAD_PER_DEG`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.RAD_PER_DEG.js), [`esnext.math.radians`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.radians.js) and [`esnext.math.scale`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.scale.js) ```js namespace Math { DEG_PER_RAD: number; RAD_PER_DEG: number; clamp(x: number, lower: number, upper: number): number; degrees(radians: number): number; fscale(x: number, inLow: number, inHigh: number, outLow: number, outHigh: number): number; radians(degrees: number): number; scale(x: number, inLow: number, inHigh: number, outLow: number, outHigh: number): number; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/math-extensions core-js(-pure)/features/math/clamp core-js(-pure)/features/math/deg-per-rad core-js(-pure)/features/math/degrees core-js(-pure)/features/math/fscale core-js(-pure)/features/math/rad-per-deg core-js(-pure)/features/math/radians core-js(-pure)/features/math/scale ``` * `Math.signbit` [proposal](https://github.com/tc39/proposal-Math.signbit) - module [`esnext.math.signbit`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.signbit.js) ```js namespace Math { signbit(x: number): boolean; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/math-signbit core-js(-pure)/features/math/signbit ``` [*Examples*](https://goo.gl/rPWbzZ): ```js Math.signbit(NaN); // => NaN Math.signbit(1); // => true Math.signbit(-1); // => false Math.signbit(0); // => true Math.signbit(-0); // => false ``` * `Number.fromString` [proposal](https://github.com/tc39/proposal-number-fromstring) - module [`esnext.number.from-string`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.number.from-string.js) ```js class Number { fromString(string: string, radix: number): number; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/number-from-string core-js(-pure)/features/number/from-string ``` * `String#codePoints` [proposal](https://github.com/tc39/proposal-string-prototype-codepoints) - module [`esnext.string.code-points`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.string.code-points.js) ```js class String { codePoints(): Iterator; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/string-code-points core-js(-pure)/features/string/code-points ``` [*Example*](https://goo.gl/Jt7SsD): ```js for (let { codePoint, position } of 'qwe'.codePoints()) { console.log(codePoint); // => 113, 119, 101 console.log(position); // => 0, 1, 2 } ``` * Seeded pseudo-random numbers [proposal](https://github.com/tc39/proposal-seeded-random) - module [`esnext.math.seeded-prng`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.seeded-prng.js) ```js class Math { seededPRNG({ seed: number }): Iterator; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/seeded-random core-js(-pure)/features/math/seeded-prng ``` [*Example*](https://goo.gl/oj3WgQ): ```js for (let x of Math.seededPRNG({ seed: 42 })) { console.log(x); // => 0.16461519912315087, 0.2203933906000046, 0.8249682894209105 if (x > .8) break; } ``` * `Symbol.patternMatch` for [pattern matching proposal](https://github.com/tc39/proposal-pattern-matching) - module [`esnext.symbol.pattern-match`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.symbol.pattern-match.js). ```js class Symbol { static patternMatch: @@patternMatch; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/pattern-matching core-js(-pure)/features/symbol/pattern-match ``` * `Symbol.dispose` for [`using` statement proposal](https://github.com/tc39/proposal-using-statement) - module [`esnext.symbol.dispose`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.symbol.dispose.js). ```js class Symbol { static dispose: @@dispose; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/using-statement core-js(-pure)/features/symbol/dispose ``` #### Stage 0 proposals [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/stage/0 ``` * `Promise.any` [proposal](https://github.com/tc39/proposal-promise-any) - modules [`esnext.promise.any`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.promise.any.js) and [`esnext.aggregate-error`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.aggregate-error.js) ```js class AggregateError { constructor(errors: Iterable, message: string): AggregateError; errors: Array; message: string; } class Promise { static any(promises: Iterable): Promise; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/promise-any core-js(-pure)/features/promise/any core-js(-pure)/features/aggregate-error ``` [*Examples*](https://goo.gl/iErvmp): ```js Promise.any([ Promise.resolve(1), Promise.reject(2), Promise.resolve(3), ]).then(console.log); // => 1 Promise.any([ Promise.reject(1), Promise.reject(2), Promise.reject(3), ]).catch(({ errors }) => console.log(errors)); // => [1, 2, 3] ``` * `URL` [proposal](https://github.com/jasnell/proposal-url), see more info [in web standards namespace](#url-and-urlsearchparams) * `String#at` [proposal](https://github.com/mathiasbynens/String.prototype.at) - module [`esnext.string.at`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.string.at.js) ```js class String { at(index: number): string; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/string-at core-js(-pure)/features/string/at core-js(-pure)/features/string/virtual/at ``` [*Examples*](http://goo.gl/XluXI8): ```js 'a𠮷b'.at(1); // => '𠮷' 'a𠮷b'.at(1).length; // => 2 ``` * Efficient 64 bit arithmetic [proposal](https://gist.github.com/BrendanEich/4294d5c212a6d2254703) - modules [`esnext.math.iaddh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.iaddh.js), [`esnext.math.isubh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.isubh.js), [`esnext.math.imulh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.imulh.js) and [`esnext.math.umulh`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.math.umulh.js) ```js namespace Math { iaddh(lo0: number, hi0: number, lo1: number, hi1: number): number; isubh(lo0: number, hi0: number, lo1: number, hi1: number): number; imulh(a: number, b: number): number; umulh(a: number, b: number): number; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/efficient-64-bit-arithmetic core-js(-pure)/features/math/iaddh core-js(-pure)/features/math/isubh core-js(-pure)/features/math/imulh core-js(-pure)/features/math/umulh ``` #### Pre-stage 0 proposals [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/stage/pre ``` * `Reflect` metadata [proposal](https://github.com/rbuckton/reflect-metadata) - modules [`esnext.reflect.define-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.define-metadata.js), [`esnext.reflect.delete-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.delete-metadata.js), [`esnext.reflect.get-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.get-metadata.js), [`esnext.reflect.get-metadata-keys`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.get-metadata-keys.js), [`esnext.reflect.get-own-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.get-own-metadata.js), [`esnext.reflect.get-own-metadata-keys`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.get-own-metadata-keys.js), [`esnext.reflect.has-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.has-metadata.js), [`esnext.reflect.has-own-metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.has-own-metadata.js) and [`esnext.reflect.metadata`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/esnext.reflect.metadata.js). ```js namespace Reflect { defineMetadata(metadataKey: any, metadataValue: any, target: Object, propertyKey?: PropertyKey): void; getMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): any; getOwnMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): any; hasMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean; hasOwnMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean; deleteMetadata(metadataKey: any, target: Object, propertyKey?: PropertyKey): boolean; getMetadataKeys(target: Object, propertyKey?: PropertyKey): Array; getOwnMetadataKeys(target: Object, propertyKey?: PropertyKey): Array; metadata(metadataKey: any, metadataValue: any): decorator(target: Object, targetKey?: PropertyKey) => void; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/reflect-metadata core-js(-pure)/features/reflect/define-metadata core-js(-pure)/features/reflect/delete-metadata core-js(-pure)/features/reflect/get-metadata core-js(-pure)/features/reflect/get-metadata-keys core-js(-pure)/features/reflect/get-own-metadata core-js(-pure)/features/reflect/get-own-metadata-keys core-js(-pure)/features/reflect/has-metadata core-js(-pure)/features/reflect/has-own-metadata core-js(-pure)/features/reflect/metadata ``` [*Examples*](http://goo.gl/KCo3PS): ```js let object = {}; Reflect.defineMetadata('foo', 'bar', object); Reflect.ownKeys(object); // => [] Reflect.getOwnMetadataKeys(object); // => ['foo'] Reflect.getOwnMetadata('foo', object); // => 'bar' ``` ### Web standards [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/web ``` #### `setTimeout` and `setInterval` Module [`web.timers`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.timers.js). Additional arguments fix for IE9-. ```js function setTimeout(callback: any, time: any, ...args: Array): number; function setInterval(callback: any, time: any, ...args: Array): number; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/web/timers core-js(-pure)/stable|features/set-timeout core-js(-pure)/stable|features/set-interval ``` ```js // Before: setTimeout(log.bind(null, 42), 1000); // After: setTimeout(log, 1000, 42); ``` #### `setImmediate` Module [`web.immediate`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.immediate.js). [`setImmediate` proposal](https://developer.mozilla.org/en-US/docs/Web/API/Window.setImmediate) polyfill. ```js function setImmediate(callback: any, ...args: Array): number; function clearImmediate(id: number): void; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/web/immediate core-js(-pure)/stable|features/set-immediate core-js(-pure)/stable|features/clear-immediate ``` [*Examples*](http://goo.gl/6nXGrx): ```js setImmediate((arg1, arg2) => { console.log(arg1, arg2); // => Message will be displayed with minimum delay }, 'Message will be displayed', 'with minimum delay'); clearImmediate(setImmediate(() => { console.log('Message will not be displayed'); })); ``` #### `queueMicrotask` [Spec](https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#dom-queuemicrotask), module [`web.queue-microtask`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.queue-microtask.js) ```js function queueMicrotask(fn: Function): void; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/web/queue-microtask core-js(-pure)/stable|features/queue-microtask ``` [*Examples*](https://goo.gl/nsW8P9): ```js queueMicrotask(() => console.log('called as microtask')); ``` #### `URL` and `URLSearchParams` [`URL` standard](https://url.spec.whatwg.org/) implementation. Modules [`web.url`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.url.js), [`web.url.to-json`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.url.to-json.js), [`web.url-search-params`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.url-search-params.js). ```js class URL { constructor(url: string, base?: string); attribute href: string; readonly attribute origin: string; attribute protocol: string; attribute username: string; attribute password: string; attribute host: string; attribute hostname: string; attribute port: string; attribute pathname: string; attribute search: string; readonly attribute searchParams: URLSearchParams; attribute hash: string; toJSON(): string; toString(): string; } class URLSearchParams { constructor(params?: string | Iterable<[key, value]> | Object); append(name: string, value: string): void; delete(name: string): void; get(name: string): string | void; getAll(name: string): Array; has(name: string): boolean; set(name: string, value: string): void; sort(): void; toString(): string; forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg: any): void; entries(): Iterator<[key, value]>; keys(): Iterator; values(): Iterator; @@iterator(): Iterator<[key, value]>; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js/proposals/url core-js(-pure)/web/url core-js(-pure)/web/url-search-params core-js(-pure)/stable|features/url core-js/stable|features/url/to-json core-js(-pure)/stable|features/url-search-params core-js/stable|features/url-search-params/sort ``` [*Examples*](https://goo.gl/kksjwV): ```js const url = new URL('http://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment'); console.log(url.href); // => 'http://login:password@example.com:8080/foo/bar?a=1&b=2#fragment' console.log(url.origin); // => 'http://example.com:8080' console.log(url.protocol); // => 'http:' console.log(url.username); // => 'login' console.log(url.password); // => 'password' console.log(url.host); // => 'example.com:8080' console.log(url.hostname); // => 'example.com' console.log(url.port); // => '8080' console.log(url.pathname); // => '/foo/bar' console.log(url.search); // => '?a=1&b=2&a=3' console.log(url.hash); // => '#fragment' console.log(url.toJSON()); // => 'http://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment' console.log(url.toString()); // => 'http://login:password@example.com:8080/foo/bar?a=1&b=2&a=3#fragment' for (let [key, value] of url.searchParams) { console.log(key); // => 'a', 'b' console.log(value); // => '1', '2' } url.pathname = ''; url.searchParams.append('c', 3); console.log(url.search); // => '?a=1&b=2&c=3' console.log(url.href); // => 'http://login:password@example.com:8080/?a=1&a=3&b=2&c=4#fragment' const params = new URLSearchParams('?a=1&b=2&a=3'); params.append('c', 4); params.append('a', 2); params.sort(); for (let [key, value] of params) { console.log(key); // => 'a', 'a', 'a', 'b', 'c' console.log(value); // => '1', '3', '2', '2', '4' } console.log(params.toString()); // => 'a=1&a=3&a=2&b=2&c=4' ``` ##### Caveats when using `URL` and `URLSearchParams`: - IE8 does not support setters, so they do not work on `URL` instances. However, `URL` constructor can be used for basic `URL` parsing. - Legacy encodings in a search query are not supported. Also, `core-js` implementation has some other encoding-related issues. - `URL` implementations from all of the popular browsers have much more problems than `core-js`, however, replacing all of them does not looks like a good idea. You can customize the aggressiveness of polyfill [by your requirements](#configurable-level-of-aggressiveness). #### Iterable DOM collections Some DOM collections should have [iterable interface](https://heycam.github.io/webidl/#idl-iterable) or should be [inherited from `Array`](https://heycam.github.io/webidl/#LegacyArrayClass). That means they should have `forEach`, `keys`, `values`, `entries` and `@@iterator` methods for iteration. So add them. Modules [`web.dom-collections.iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.dom-collections.iterator.js) and [`web.dom-collections.for-each`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/web.dom-collections.for-each.js). ```js class [ CSSRuleList, CSSStyleDeclaration, CSSValueList, ClientRectList, DOMRectList, DOMStringList, DataTransferItemList, FileList, HTMLAllCollection, HTMLCollection, HTMLFormElement, HTMLSelectElement, MediaList, MimeTypeArray, NamedNodeMap, PaintRequestList, Plugin, PluginArray, SVGLengthList, SVGNumberList, SVGPathSegList, SVGPointList, SVGStringList, SVGTransformList, SourceBufferList, StyleSheetList, TextTrackCueList, TextTrackList, TouchList, ] { @@iterator(): Iterator; } class [DOMTokenList, NodeList] { forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg: any): void; entries(): Iterator<[key, value]>; keys(): Iterator; values(): Iterator; @@iterator(): Iterator; } ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js(-pure)/web/dom-collections core-js(-pure)/stable|features/dom-collections/iterator core-js/stable|features/dom-collections/for-each ``` [*Examples*](http://goo.gl/lfXVFl): ```js for (let { id } of document.querySelectorAll('*')) { if (id) console.log(id); } for (let [index, { id }] of document.querySelectorAll('*').entries()) { if (id) console.log(index, id); } document.querySelectorAll('*').forEach(it => console.log(it.id)); ``` ### Iteration helpers Modules [`core.is-iterable`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/core.is-iterable.js), [`core.get-iterator`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/core.get-iterator.js), [`core.get-iterator-method`](https://github.com/zloirock/core-js/blob/v3.0.0/packages/core-js/modules/core.get-iterator-method.js) - helpers for check iterability / get iterator in the `pure` version or, for example, for `arguments` object: ```js function isIterable(value: any): boolean; function getIterator(value: any): Object; function getIteratorMethod(value: any): Function | void; ``` [*CommonJS entry points:*](#commonjs-api) ```js core-js-pure/features/is-iterable core-js-pure/features/get-iterator core-js-pure/features/get-iterator-method ``` [*Examples*](http://goo.gl/SXsM6D): ```js import isIterable from 'core-js-pure/features/is-iterable'; import getIterator from 'core-js-pure/features/get-iterator'; import getIteratorMethod from 'core-js-pure/features/get-iterator-method'; let list = (function () { return arguments; })(1, 2, 3); console.log(isIterable(list)); // true; let iterator = getIterator(list); console.log(iterator.next().value); // 1 console.log(iterator.next().value); // 2 console.log(iterator.next().value); // 3 console.log(iterator.next().value); // undefined getIterator({}); // TypeError: [object Object] is not iterable! let method = getIteratorMethod(list); console.log(typeof method); // 'function' let iterator = method.call(list); console.log(iterator.next().value); // 1 console.log(iterator.next().value); // 2 console.log(iterator.next().value); // 3 console.log(iterator.next().value); // undefined console.log(getIteratorMethod({})); // undefined ``` ## Missing polyfills - ES `String#normalize` is not a very useful feature, but this polyfill will be very large. If you need it, you can use [unorm](https://github.com/walling/unorm/). - ES `Proxy` can't be polyfilled, but for Node.js / Chromium with additional flags, you can try [harmony-reflect](https://github.com/tvcutsem/harmony-reflect) for adapt old style `Proxy` API to final ES2015 version. - `window.fetch` is not a cross-platform feature, in some environments, it makes no sense. For this reason, I don't think it should be in `core-js`. Looking at a large number of requests it *might be* added in the future. Now you can use, for example, [this polyfill](https://github.com/github/fetch). - ECMA-402 `Intl` is missed because of the size. You can use [this polyfill](https://github.com/andyearnshaw/Intl.js/).