![logo](https://user-images.githubusercontent.com/2213682/146607186-8e13ddef-26a4-4ebf-befd-5aac9d77c090.png) [![Open Collective](https://opencollective.com/core-js/all/badge.svg?label=open%20collective)](https://opencollective.com/core-js) [![version](https://img.shields.io/npm/v/core-js.svg)](https://www.npmjs.com/package/core-js) [![core-js downloads](https://img.shields.io/npm/dm/core-js.svg?label=npm%20i%20core-js)](https://npm-stat.com/charts.html?package=core-js&package=core-js-pure&package=core-js-compat&from=2014-11-18) [![core-js-pure downloads](https://img.shields.io/npm/dm/core-js-pure.svg?label=npm%20i%20core-js-pure)](https://npm-stat.com/charts.html?package=core-js&package=core-js-pure&package=core-js-compat&from=2014-11-18) [![tests](https://github.com/zloirock/core-js/workflows/tests/badge.svg)](https://github.com/zloirock/core-js/actions) [![eslint](https://github.com/zloirock/core-js/workflows/eslint/badge.svg)](https://github.com/zloirock/core-js/actions) > Modular standard library for JavaScript. Includes polyfills for [ECMAScript up to 2021](https://github.com/zloirock/core-js#ecmascript): [promises](https://github.com/zloirock/core-js#ecmascript-promise), [symbols](https://github.com/zloirock/core-js#ecmascript-symbol), [collections](https://github.com/zloirock/core-js#ecmascript-collections), iterators, [typed arrays](https://github.com/zloirock/core-js#ecmascript-typed-arrays), many other features, [ECMAScript proposals](https://github.com/zloirock/core-js#ecmascript-proposals), [some cross-platform WHATWG / W3C features and proposals](#web-standards) like [`URL`](https://github.com/zloirock/core-js#url-and-urlsearchparams). You can load only required features or use it without global namespace pollution. ## 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) ## Raising funds `core-js` isn't backed by a company, so the future of this project depends on you. Become a sponsor or a backer if you are interested in `core-js`: [**Open Collective**](https://opencollective.com/core-js), [**Patreon**](https://patreon.com/zloirock), **Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz )**. --- --- --- [*Example of usage*](https://is.gd/XD4mRe): ```js import 'core-js/actual'; // <- at the top of your entry point Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] [1, 2, 3, 4, 5].groupBy(it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] } Promise.resolve(42).then(x => console.log(x)); // => 42 structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3]) queueMicrotask(() => console.log('called as microtask')); ``` *You can load only required features*: ```js import 'core-js/actual/array/from'; // <- at the top of your entry point import 'core-js/actual/array/group-by'; // <- at the top of your entry point import 'core-js/actual/set'; // <- at the top of your entry point import 'core-js/actual/promise'; // <- at the top of your entry point import 'core-js/actual/structured-clone'; // <- at the top of your entry point import 'core-js/actual/queue-microtask'; // <- at the top of your entry point Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] [1, 2, 3, 4, 5].groupBy(it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] } Promise.resolve(42).then(x => console.log(x)); // => 42 structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3]) queueMicrotask(() => console.log('called as microtask')); ``` *Or use it without global namespace pollution*: ```js import from from 'core-js-pure/actual/array/from'; import groupBy from 'core-js-pure/actual/array/group-by'; import Set from 'core-js-pure/actual/set'; import Promise from 'core-js-pure/actual/promise'; import structuredClone from 'core-js-pure/actual/structured-clone'; import queueMicrotask from 'core-js-pure/actual/queue-microtask'; from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3] groupBy([1, 2, 3, 4, 5], it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] } Promise.resolve(42).then(x => console.log(x)); // => 42 structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3]) queueMicrotask(() => console.log('called as microtask')); ``` **It's a version without global namespace pollution (the third example), for more info see [`core-js` documentation](https://github.com/zloirock/core-js/blob/master/README.md)**.