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core-js
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core-js

LICENSE
README.md
actual/
configurator.js
es/
features/
full/
index.js
internals/
modules/
package.json
postinstall.js
proposals/
stable/
stage/
web/

README.md

!logo

![fundraising](https://opencollective.com/core-js) ![PRs welcome](https://github.com/zloirock/core-js/blob/master/CONTRIBUTING.md) ![version](https://www.npmjs.com/package/core-js) ![core-js downloads](https://npm-stat.com/charts.html?package=core-js&package=core-js-pure&package=core-js-compat&from=2014-11-18)

</div>

Modular standard library for JavaScript. Includes polyfills for ECMAScript up to 2023: promises, symbols, collections, iterators, typed arrays, many other features, 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

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**, **Patreon**, Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz ).

*Example of usage*:

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].group(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';      // <- 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].group(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 group from 'core-js-pure/actual/array/group';
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]
group([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 global version (first 2 examples), for more info see [core-js documentation](https://github.com/zloirock/core-js/blob/master/README.md).**