1 | # core-js
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2 |
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3 | [![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)
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4 |
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5 | > 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.
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6 |
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7 | ## As advertising: the author is looking for a good job -)
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8 |
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9 | ## [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)
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10 |
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11 | ## Raising funds
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12 |
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13 | `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), [**PayPal**](https://paypal.me/zloirock), **Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz )**.
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14 |
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15 | ---
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16 |
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17 | <a href="https://opencollective.com/core-js/sponsor/0/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/0/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/1/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/1/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/2/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/2/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/3/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/3/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/4/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/4/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/5/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/5/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/6/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/6/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/7/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/7/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/8/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/8/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/9/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/9/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/10/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/10/avatar.svg"></a><a href="https://opencollective.com/core-js/sponsor/11/website" target="_blank"><img src="https://opencollective.com/core-js/sponsor/11/avatar.svg"></a>
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18 |
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19 | ---
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20 |
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21 | <a href="https://opencollective.com/core-js#backers" target="_blank"><img src="https://opencollective.com/core-js/backers.svg?width=890"></a>
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22 |
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23 | ---
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24 |
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25 | [*Example*](http://goo.gl/a2xexl):
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26 | ```js
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27 | import 'core-js'; // <- at the top of your entry point
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28 |
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29 | Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
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30 | [1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5]
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31 | Promise.resolve(32).then(x => console.log(x)); // => 32
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32 | ```
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33 |
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34 | *You can load only required features*:
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35 | ```js
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36 | import 'core-js/features/array/from'; // <- at the top of your entry point
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37 | import 'core-js/features/array/flat'; // <- at the top of your entry point
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38 | import 'core-js/features/set'; // <- at the top of your entry point
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39 | import 'core-js/features/promise'; // <- at the top of your entry point
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40 |
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41 | Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
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42 | [1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5]
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43 | Promise.resolve(32).then(x => console.log(x)); // => 32
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44 | ```
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45 |
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46 | *Or use it without global namespace pollution*:
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47 | ```js
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48 | import from from 'core-js-pure/features/array/from';
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49 | import flat from 'core-js-pure/features/array/flat';
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50 | import Set from 'core-js-pure/features/set';
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51 | import Promise from 'core-js-pure/features/promise';
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52 |
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53 | from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
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54 | flat([1, [2, 3], [4, [5]]], 2); // => [1, 2, 3, 4, 5]
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55 | Promise.resolve(32).then(x => console.log(x)); // => 32
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56 | ```
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57 |
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58 | **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).**
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