-
-
Notifications
You must be signed in to change notification settings - Fork 1.6k
/
README.md
3679 lines (3334 loc) · 188 KB
/
README.md
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<div align="center">
[](https://opencollective.com/core-js) [](https://github.com/zloirock/core-js/blob/master/CONTRIBUTING.md) [](https://www.npmjs.com/package/core-js) [](https://npm-stat.com/charts.html?package=core-js&package=core-js-pure&package=core-js-compat&from=2014-11-18) [](https://npm-stat.com/charts.html?package=core-js&package=core-js-pure&package=core-js-compat&from=2014-11-18) [](https://www.jsdelivr.com/package/npm/core-js-bundle)
</div>
**I highly recommend reading this: [So, what's next?](https://github.com/zloirock/core-js/blob/master/docs/2023-02-14-so-whats-next.md)**
---
> Modular standard library for JavaScript. Includes polyfills for [ECMAScript up to 2024](#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.
**If you are looking for documentation for obsolete `core-js@2`, please, check [this branch](https://github.com/zloirock/core-js/tree/v2).**
## [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), [**Boosty**](https://boosty.to/zloirock), **Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz )**, [**Alipay**](https://user-images.githubusercontent.com/2213682/219464783-c17ad329-17ce-4795-82a7-f609493345ed.png).
---
<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>
---
<a href="https://opencollective.com/core-js#backers" target="_blank"><img src="https://opencollective.com/core-js/backers.svg?width=890"></a>
---
[*Example of usage*](https://tinyurl.com/2mknex43):
```js
import 'core-js/actual';
Promise.resolve(42).then(it => console.log(it)); // => 42
Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]
(function * (i) { while (true) yield i++; })(1)
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])
```
*You can load only required features*:
```js
import 'core-js/actual/promise';
import 'core-js/actual/set';
import 'core-js/actual/iterator';
import 'core-js/actual/array/from';
import 'core-js/actual/array/flat-map';
import 'core-js/actual/structured-clone';
Promise.resolve(42).then(it => console.log(it)); // => 42
Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]
(function * (i) { while (true) yield i++; })(1)
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])
```
*Or use it without global namespace pollution*:
```js
import Promise from 'core-js-pure/actual/promise';
import Set from 'core-js-pure/actual/set';
import Iterator from 'core-js-pure/actual/iterator';
import from from 'core-js-pure/actual/array/from';
import flatMap from 'core-js-pure/actual/array/flat-map';
import structuredClone from 'core-js-pure/actual/structured-clone';
Promise.resolve(42).then(it => console.log(it)); // => 42
from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]
flatMap([1, 2], it => [it, it]); // => [1, 1, 2, 2]
Iterator.from(function * (i) { while (true) yield i++; }(1))
.drop(1).take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])
```
### Index
- [Usage](#usage)
- [Installation](#installation)
- [`postinstall` message](#postinstall-message)
- [CommonJS API](#commonjs-api)
- [Babel](#babel)
- [`@babel/polyfill`](#babelpolyfill)
- [`@babel/preset-env`](#babelpreset-env)
- [`@babel/runtime`](#babelruntime)
- [swc](#swc)
- [Configurable level of aggressiveness](#configurable-level-of-aggressiveness)
- [Custom build](#custom-build)
- [Supported engines and compatibility data](#supported-engines-and-compatibility-data)
- [Features](#features)
- [ECMAScript](#ecmascript)
- [ECMAScript: Object](#ecmascript-object)
- [ECMAScript: Function](#ecmascript-function)
- [ECMAScript: Error](#ecmascript-error)
- [ECMAScript: Array](#ecmascript-array)
- [ECMAScript: Iterator](#ecmascript-iterator)
- [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: JSON](#ecmascript-json)
- [ECMAScript: globalThis](#ecmascript-globalthis)
- [ECMAScript proposals](#ecmascript-proposals)
- [Finished proposals](#finished-proposals)
- [`globalThis`](#globalthis)
- [Relative indexing method](#relative-indexing-method)
- [`Array.prototype.includes`](#arrayprototypeincludes)
- [`Array.prototype.flat` / `Array.prototype.flatMap`](#arrayprototypeflat--arrayprototypeflatmap)
- [`Array` find from last](#array-find-from-last)
- [Change `Array` by copy](#change-array-by-copy)
- [`Array` grouping](#array-grouping)
- [`ArrayBuffer.prototype.transfer` and friends](#arraybufferprototypetransfer-and-friends)
- [`Iterator` helpers](#iterator-helpers)
- [`Object.values` / `Object.entries`](#objectvalues--objectentries)
- [`Object.fromEntries`](#objectfromentries)
- [`Object.getOwnPropertyDescriptors`](#objectgetownpropertydescriptors)
- [Accessible `Object.prototype.hasOwnProperty`](#accessible-objectprototypehasownproperty)
- [`String` padding](#string-padding)
- [`String.prototype.matchAll`](#stringmatchall)
- [`String.prototype.replaceAll`](#stringreplaceall)
- [`String.prototype.trimStart` / `String.prototype.trimEnd`](#stringprototypetrimstart-stringprototypetrimend)
- [`RegExp` `s` (`dotAll`) flag](#regexp-s-dotall-flag)
- [`RegExp` named capture groups](#regexp-named-capture-groups)
- [`Promise.allSettled`](#promiseallsettled)
- [`Promise.any`](#promiseany)
- [`Promise.prototype.finally`](#promiseprototypefinally)
- [`Promise.try`](#promisetry)
- [`Promise.withResolvers`](#promisewithresolvers)
- [`Symbol.asyncIterator` for asynchronous iteration](#symbolasynciterator-for-asynchronous-iteration)
- [`Symbol.prototype.description`](#symbolprototypedescription)
- [Well-formed `JSON.stringify`](#well-formed-jsonstringify)
- [Well-formed unicode strings](#well-formed-unicode-strings)
- [New `Set` methods](#new-set-methods)
- [Stage 3 proposals](#stage-3-proposals)
- [`Array.fromAsync`](#arrayfromasync)
- [`JSON.parse` source text access](#jsonparse-source-text-access)
- [`Float16` methods](#float16-methods)
- [`Uint8Array` to / from base64 and hex](#uint8array-to--from-base64-and-hex)
- [Explicit resource management](#explicit-resource-management)
- [`RegExp` escaping](#regexp-escaping)
- [`Math.sumPrecise`](#mathsumprecise)
- [`Symbol.metadata` for decorators metadata proposal](#symbolmetadata-for-decorators-metadata-proposal)
- [Stage 2.7 proposals](#stage-27-proposals)
- [`Iterator` sequencing](#iterator-sequencing)
- [Stage 2 proposals](#stage-2-proposals)
- [`AsyncIterator` helpers](#asynciterator-helpers)
- [`Iterator.range`](#iteratorrange)
- [`Map` upsert](#map-upsert)
- [`Array.isTemplateObject`](#arrayistemplateobject)
- [`String.dedent`](#stringdedent)
- [`Symbol` predicates](#symbol-predicates)
- [`Symbol.customMatcher` for extractors](#symbolcustommatcher-for-extractors)
- [Stage 1 proposals](#stage-1-proposals)
- [`Observable`](#observable)
- [New collections methods](#new-collections-methods)
- [`.of` and `.from` methods on collection constructors](#of-and-from-methods-on-collection-constructors)
- [`compositeKey` and `compositeSymbol`](#compositekey-and-compositesymbol)
- [`Array` filtering](#array-filtering)
- [`Array` deduplication](#array-deduplication)
- [`DataView` get / set `Uint8Clamped` methods](#dataview-get-set-iint8clamped-methods)
- [`Number.fromString`](#numberfromstring)
- [`String.cooked`](#stringcooked)
- [`String.prototype.codePoints`](#stringprototypecodepoints)
- [`Symbol.customMatcher` for pattern matching](#symbolcustommatcher-for-pattern-matching)
- [Stage 0 proposals](#stage-0-proposals)
- [`Function.prototype.demethodize`](#functionprototypedemethodize)
- [`Function.{ isCallable, isConstructor }`](#function-iscallable-isconstructor-)
- [Pre-stage 0 proposals](#pre-stage-0-proposals)
- [`Reflect` metadata](#reflect-metadata)
- [Web standards](#web-standards)
- [`self`](#self)
- [`structuredClone`](#structuredclone)
- [Base64 utility methods](#base64-utility-methods)
- [`setTimeout` and `setInterval`](#settimeout-and-setinterval)
- [`setImmediate`](#setimmediate)
- [`queueMicrotask`](#queuemicrotask)
- [`URL` and `URLSearchParams`](#url-and-urlsearchparams)
- [`DOMException`](#domexception)
- [iterable DOM collections](#iterable-dom-collections)
- [Iteration helpers](#iteration-helpers)
- [Missing polyfills](#missing-polyfills)
- [Contributing](./CONTRIBUTING.md)
- [Security policy](https://github.com/zloirock/core-js/blob/master/SECURITY.md)
- [Changelog](./CHANGELOG.md)
## Usage[⬆](#index)
### Installation:[⬆](#index)
```sh
// global version
npm install --save [email protected]
// version without global namespace pollution
npm install --save [email protected]
// bundled global version
npm install --save [email protected]
```
Or you can use `core-js` [from CDN](https://www.jsdelivr.com/package/npm/core-js-bundle).
### `postinstall` message[⬆](#index)
The `core-js` project needs your help, so the package shows a message about it after installation. If it causes problems for you, you can disable it:
```sh
ADBLOCK=true npm install
// or
DISABLE_OPENCOLLECTIVE=true npm install
// or
npm install --loglevel silent
```
### CommonJS API[⬆](#index)
You can import only-required-for-you polyfills, like in the examples at the top of `README.md`. Available CommonJS entry points for all polyfilled methods / constructors and namespaces. Just some examples:
```ts
// polyfill all `core-js` features, including early-stage proposals:
import "core-js";
// or:
import "core-js/full";
// polyfill all actual features - stable ES, web standards and stage 3 ES proposals:
import "core-js/actual";
// polyfill only stable features - ES and web standards:
import "core-js/stable";
// polyfill only stable ES features:
import "core-js/es";
// if you want to polyfill `Set`:
// all `Set`-related features, with early-stage ES proposals:
import "core-js/full/set";
// stable required for `Set` ES features, features from web standards and stage 3 ES proposals:
import "core-js/actual/set";
// stable required for `Set` ES features and features from web standards
// (DOM collections iterator in this case):
import "core-js/stable/set";
// only stable ES features required for `Set`:
import "core-js/es/set";
// the same without global namespace pollution:
import Set from "core-js-pure/full/set";
import Set from "core-js-pure/actual/set";
import Set from "core-js-pure/stable/set";
import Set from "core-js-pure/es/set";
// if you want to polyfill just the required methods:
import "core-js/full/set/intersection";
import "core-js/actual/array/find-last";
import "core-js/stable/queue-microtask";
import "core-js/es/array/from";
// polyfill iterator helpers proposal:
import "core-js/proposals/iterator-helpers";
// polyfill all stage 2+ proposals:
import "core-js/stage/2";
```
> [!TIP]
> The usage of the `/actual/` namespace is recommended since it includes all actual JavaScript features and does not include unstable early-stage proposals that are available mainly for experiments.
> [!WARNING]
> - The `modules` path is an internal API, does not inject all required dependencies and can be changed in minor or patch releases. Use it only for a custom build and/or if you know what are you doing.
> - If you use `core-js` with the extension of native objects, recommended to load all `core-js` modules at the top of the entry point of your application, otherwise, you can have conflicts.
> - For example, Google Maps use their own `Symbol.iterator`, conflicting with `Array.from`, `URLSearchParams` and / or something else from `core-js`, see [related issues](https://github.com/zloirock/core-js/search?q=Google+Maps&type=Issues).
> - Such conflicts are also resolvable by discovering and manually adding each conflicting entry from `core-js`.
> - `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 a usage loader for each file, otherwise, you will have hundreds of requests.
#### CommonJS and prototype methods without global namespace pollution[⬆](#index)
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:
```ts
import fill from 'core-js-pure/actual/array/virtual/fill';
import findIndex from 'core-js-pure/actual/array/virtual/find-index';
Array(10)::fill(0).map((a, b) => b * b)::findIndex(it => it && !(it % 8)); // => 4
```
> [!WARNING]
> The bind operator is an early-stage ECMAScript proposal and usage of this syntax can be dangerous.
### Babel[⬆](#index)
`core-js` is integrated with `babel` and is the base for polyfilling-related `babel` features:
#### `@babel/polyfill`[⬆](#index)
[`@babel/polyfill`](https://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 favor 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`[⬆](#index)
[`@babel/preset-env`](https://github.com/babel/babel/tree/master/packages/babel-preset-env) has `useBuiltIns` option, which optimizes working with the global version of `core-js`. With `useBuiltIns` option, you should also set `corejs` option to the used version of `core-js`, like `corejs: '3.39'`.
> [!IMPORTANT]
> Recommended to specify used minor `core-js` version, like `corejs: '3.39'`, instead of `corejs: 3`, since with `corejs: 3` will not be injected modules which were added in minor `core-js` releases.
---
- `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/full/set/map';
```
with `chrome 71` target you will have as the 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'` adds to 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:
let set = new Set([1, 2, 3]);
```
```js
// second file:
let array = Array.of(1, 2, 3);
```
if the 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]);
```
```js
// 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 only polyfills stable features, but you can enable polyfilling of proposals by the `proposals` option, as `corejs: { version: '3.39', proposals: true }`.
> [!IMPORTANT]
> In the case of `useBuiltIns: 'usage'`, you should not add `core-js` imports by yourself, they will be added automatically.
#### `@babel/runtime`[⬆](#index)
[`@babel/runtime`](https://babeljs.io/docs/plugins/transform-runtime/) with `corejs: 3` option simplifies work with the `core-js-pure`. It automatically replaces the usage of modern features from the 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` only polyfills stable features, but like in `@babel/preset-env`, you can enable polyfilling of proposals by `proposals` option, as `corejs: { version: 3, proposals: true }`.
> [!WARNING]
> If you use `@babel/preset-env` and `@babel/runtime` together, use `corejs` option only in one place since it's duplicate functionality and will cause conflicts.
### swc[⬆](#index)
Fast JavaScript transpiler `swc` [contains integration with `core-js`](https://swc.rs/docs/configuration/supported-browsers), that optimizes work with the global version of `core-js`. [Like `@babel/preset-env`](#babelpreset-env), it has 2 modes: `usage` and `entry`, but `usage` mode still works not so well as in `babel`. Example of configuration in `.swcrc`:
```json
{
"env": {
"targets": "> 0.25%, not dead",
"mode": "entry",
"coreJs": "3.39"
}
}
```
### Configurable level of aggressiveness[⬆](#index)
By default, `core-js` sets polyfills only when they are required. That means that `core-js` checks if a feature is available and works correctly or not and if it has no problems, `core-js` uses 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 an inverse problem - a knowingly broken environment with problems not covered by `core-js` feature detection.
For those cases, we could redefine this behavior for certain polyfills:
```js
const configurator = require('core-js/configurator');
configurator({
useNative: ['Promise'], // polyfills will be used only if natives are completely unavailable
usePolyfill: ['Array.from', 'String.prototype.padEnd'], // polyfills will be used anyway
useFeatureDetection: ['Map', 'Set'], // default behavior
});
require('core-js/actual');
```
It does not work with some features. Also, if you change the default behavior, even `core-js` internals may not work correctly.
### Custom build[⬆](#index)
For some cases could be useful to exclude some `core-js` features or generate a polyfill for target engines. You could use [`core-js-builder`](/packages/core-js-builder) package for that.
## Supported engines and compatibility data[⬆](#index)
`core-js` tries to support all possible JS engines and environments with ES3 support. Some features have a higher lower bar - for example, *some* accessors can properly work only from ES5, promises require a way to set a microtask or a task, etc.
However, I have no possibility to test `core-js` absolutely everywhere - for example, testing in IE7- and some other ancient was stopped. The list of definitely supported engines you can see in the compatibility table by the link below. [Write](https://github.com/zloirock/core-js/issues) if you have issues or questions with the support of any engine.
`core-js` project provides (as [`core-js-compat`](/packages/core-js-compat) package) all required data about the necessity of `core-js` modules, entry points, and tools for work with it - it's useful for integration with tools like `babel` or `swc`. If you wanna help, you could take a look at the related section of [`CONTRIBUTING.md`](/CONTRIBUTING.md#how-to-update-core-js-compat-data). The visualization of compatibility data and the browser tests runner is available [here](http://zloirock.github.io/core-js/compat/), the example:
## Features:[⬆](#index)
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)
```
### ECMAScript[⬆](#index)
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es
```
#### ECMAScript: Object[⬆](#index)
Modules [`es.object.assign`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.assign.js), [`es.object.create`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.create.js), [`es.object.define-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-getter.js), [`es.object.define-property`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-property.js), [`es.object.define-properties`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-properties.js), [`es.object.define-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.define-setter.js), [`es.object.entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.entries.js), [`es.object.freeze`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.freeze.js), [`es.object.from-entries`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.from-entries.js), [`es.object.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptor.js), [`es.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-descriptors.js), [`es.object.get-own-property-names`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-own-property-names.js), [`es.object.get-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.get-prototype-of.js), [`es.object.group-by`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.group-by.js), [`es.object.has-own`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.has-own.js), [`es.object.is`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is.js), [`es.object.is-extensible`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-extensible.js), [`es.object.is-frozen`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-frozen.js), [`es.object.is-sealed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.is-sealed.js), [`es.object.keys`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.keys.js), [`es.object.lookup-setter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-setter.js), [`es.object.lookup-getter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.lookup-getter.js), [`es.object.prevent-extensions`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.prevent-extensions.js), [`es.object.proto`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.proto.js), [`es.object.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.to-string.js), [`es.object.seal`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.seal.js), [`es.object.set-prototype-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.set-prototype-of.js), [`es.object.values`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.object.values.js).
```ts
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;
__proto__: Object | null; // required a way setting of prototype - will not in IE10-, it's for modern engines like Deno
static assign(target: Object, ...sources: Array<Object>): 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<string>;
static getPrototypeOf(object: any): Object | null;
static groupBy(items: Iterable, callbackfn: (value: any, index: number) => key): { [key]: Array<mixed> };
static hasOwn(object: object, key: PropertyKey): boolean;
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<string>;
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<mixed>;
}
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es|stable|actual|full/object
core-js(-pure)/es|stable|actual|full/object/assign
core-js(-pure)/es|stable|actual|full/object/is
core-js(-pure)/es|stable|actual|full/object/set-prototype-of
core-js(-pure)/es|stable|actual|full/object/get-prototype-of
core-js(-pure)/es|stable|actual|full/object/create
core-js(-pure)/es|stable|actual|full/object/define-property
core-js(-pure)/es|stable|actual|full/object/define-properties
core-js(-pure)/es|stable|actual|full/object/get-own-property-descriptor
core-js(-pure)/es|stable|actual|full/object/get-own-property-descriptors
core-js(-pure)/es|stable|actual|full/object/group-by
core-js(-pure)/es|stable|actual|full/object/has-own
core-js(-pure)/es|stable|actual|full/object/keys
core-js(-pure)/es|stable|actual|full/object/values
core-js(-pure)/es|stable|actual|full/object/entries
core-js(-pure)/es|stable|actual|full/object/get-own-property-names
core-js(-pure)/es|stable|actual|full/object/freeze
core-js(-pure)/es|stable|actual|full/object/from-entries
core-js(-pure)/es|stable|actual|full/object/seal
core-js(-pure)/es|stable|actual|full/object/prevent-extensions
core-js/es|stable|actual|full/object/proto
core-js(-pure)/es|stable|actual|full/object/is-frozen
core-js(-pure)/es|stable|actual|full/object/is-sealed
core-js(-pure)/es|stable|actual|full/object/is-extensible
core-js/es|stable|actual|full/object/to-string
core-js(-pure)/es|stable|actual|full/object/define-getter
core-js(-pure)/es|stable|actual|full/object/define-setter
core-js(-pure)/es|stable|actual|full/object/lookup-getter
core-js(-pure)/es|stable|actual|full/object/lookup-setter
```
*Examples*:
```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() { /* empty */ }
function Child() { /* empty */ }
Object.setPrototypeOf(Child.prototype, Parent.prototype);
new Child() instanceof Child; // => true
new Child() instanceof Parent; // => true
({
[Symbol.toStringTag]: 'Foo',
}).toString(); // => '[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 } }
Object.hasOwn({ foo: 42 }, 'foo'); // => true
Object.hasOwn({ foo: 42 }, 'bar'); // => false
Object.hasOwn({}, 'toString'); // => false
Object.groupBy([1, 2, 3, 4, 5], it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] }
```
#### ECMAScript: Function[⬆](#index)
Modules [`es.function.name`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.function.name.js), [`es.function.has-instance`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.function.has-instance.js). Just ES5: [`es.function.bind`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.function.bind.js).
```ts
class Function {
name: string;
bind(thisArg: any, ...args: Array<mixed>): Function;
@@hasInstance(value: any): boolean;
}
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js/es|stable|actual|full/function
core-js/es|stable|actual|full/function/name
core-js/es|stable|actual|full/function/has-instance
core-js(-pure)/es|stable|actual|full/function/bind
core-js(-pure)/es|stable|actual|full/function/virtual/bind
```
[*Example*](https://tinyurl.com/22na9nbm):
```js
(function foo() { /* empty */ }).name; // => 'foo'
console.log.bind(console, 42)(43); // => 42 43
```
#### ECMAScript: Error[⬆](#index)
Modules [`es.aggregate-error`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.js), [`es.aggregate-error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.aggregate-error.cause.js), [`es.error.cause`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.cause.js), [`es.error.to-string`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.error.to-string.js).
```ts
class [
Error,
EvalError,
RangeError,
ReferenceError,
SyntaxError,
TypeError,
URIError,
WebAssembly.CompileError,
WebAssembly.LinkError,
WebAssembly.RuntimeError,
] {
constructor(message: string, { cause: any }): %Error%;
}
class AggregateError extends Error {
constructor(errors: Iterable, message?: string, { cause: any }?): AggregateError;
errors: Array<any>;
message: string;
cause: any;
}
class Error {
toString(): string; // different fixes
}
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es|stable|actual|full/aggregate-error
core-js/es|stable|actual|full/error
core-js/es|stable|actual|full/error/constructor
core-js/es|stable|actual|full/error/to-string
```
[*Example*](https://is.gd/1SufcH):
```js
const error1 = new TypeError('Error 1');
const error2 = new TypeError('Error 2');
const aggregate = new AggregateError([error1, error2], 'Collected errors');
aggregate.errors[0] === error1; // => true
aggregate.errors[1] === error2; // => true
const cause = new TypeError('Something wrong');
const error = new TypeError('Here explained what`s wrong', { cause });
error.cause === cause; // => true
Error.prototype.toString.call({ message: 1, name: 2 }) === '2: 1'; // => true
```
#### ECMAScript: Array[⬆](#index)
Modules [`es.array.from`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.from.js), [`es.array.is-array`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.is-array.js), [`es.array.of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.of.js), [`es.array.copy-within`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.copy-within.js), [`es.array.fill`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.fill.js), [`es.array.find`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find.js), [`es.array.find-index`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-index.js), [`es.array.find-last`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-last.js), [`es.array.find-last-index`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.find-last-index.js), [`es.array.iterator`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.iterator.js), [`es.array.includes`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.includes.js), [`es.array.push`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.push.js), [`es.array.slice`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.slice.js), [`es.array.join`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.join.js), [`es.array.unshift`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unshift.js), [`es.array.index-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.index-of.js), [`es.array.last-index-of`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.last-index-of.js), [`es.array.every`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.every.js), [`es.array.some`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.some.js), [`es.array.for-each`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.for-each.js), [`es.array.map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.map.js), [`es.array.filter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.filter.js), [`es.array.reduce`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reduce.js), [`es.array.reduce-right`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reduce-right.js), [`es.array.reverse`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.reverse.js), [`es.array.sort`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.sort.js), [`es.array.flat`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.flat.js), [`es.array.flat-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.flat-map.js), [`es.array.unscopables.flat`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unscopables.flat.js), [`es.array.unscopables.flat-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.unscopables.flat-map.js), [`es.array.at`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.at.js), [`es.array.to-reversed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-reversed.js), [`es.array.to-sorted`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-sorted.js), [`es.array.to-spliced`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.to-spliced.js), [`es.array.with`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.array.with.js).
```ts
class Array {
at(index: int): any;
concat(...args: Array<mixed>): Array<mixed>; // 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<mixed>; // 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): uint;
findLast(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): any;
findLastIndex(callbackfn: (value: any, index: number, target: any) => boolean, thisArg?: any): uint;
flat(depthArg?: number = 1): Array<mixed>;
flatMap(mapFn: (value: any, index: number, target: any) => any, thisArg: any): Array<mixed>;
forEach(callbackfn: (value: any, index: number, target: any) => void, thisArg?: any): void;
includes(searchElement: any, from?: number): boolean;
indexOf(searchElement: any, from?: number): number;
join(separator: string = ','): string;
keys(): Iterator<index>;
lastIndexOf(searchElement: any, from?: number): number;
map(mapFn: (value: any, index: number, target: any) => any, thisArg?: any): Array<mixed>; // with adding support of @@species
push(...args: Array<mixed>): uint;
reduce(callbackfn: (memo: any, value: any, index: number, target: any) => any, initialValue?: any): any;
reduceRight(callbackfn: (memo: any, value: any, index: number, target: any) => any, initialValue?: any): any;
reverse(): this; // Safari 12.0 bug fix
slice(start?: number, end?: number): Array<mixed>; // with adding support of @@species
splice(start?: number, deleteCount?: number, ...items: Array<mixed>): Array<mixed>; // 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; // with modern behavior like stable sort
toReversed(): Array<mixed>;
toSpliced(start?: number, deleteCount?: number, ...items: Array<mixed>): Array<mixed>;
toSorted(comparefn?: (a: any, b: any) => number): Array<mixed>;
unshift(...args: Array<mixed>): uint;
values(): Iterator<value>;
with(index: includes, value: any): Array<mixed>;
@@iterator(): Iterator<value>;
@@unscopables: { [newMethodNames: string]: true };
static from(items: Iterable | ArrayLike, mapFn?: (value: any, index: number) => any, thisArg?: any): Array<mixed>;
static isArray(value: any): boolean;
static of(...args: Array<mixed>): Array<mixed>;
}
class Arguments {
@@iterator(): Iterator<value>; // available only in core-js methods
}
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es|stable|actual|full/array
core-js(-pure)/es|stable|actual|full/array/from
core-js(-pure)/es|stable|actual|full/array/of
core-js(-pure)/es|stable|actual|full/array/is-array
core-js(-pure)/es|stable|actual|full/array(/virtual)/at
core-js(-pure)/es|stable|actual|full/array(/virtual)/concat
core-js(-pure)/es|stable|actual|full/array(/virtual)/copy-within
core-js(-pure)/es|stable|actual|full/array(/virtual)/entries
core-js(-pure)/es|stable|actual|full/array(/virtual)/every
core-js(-pure)/es|stable|actual|full/array(/virtual)/fill
core-js(-pure)/es|stable|actual|full/array(/virtual)/filter
core-js(-pure)/es|stable|actual|full/array(/virtual)/find
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-index
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-last
core-js(-pure)/es|stable|actual|full/array(/virtual)/find-last-index
core-js(-pure)/es|stable|actual|full/array(/virtual)/flat
core-js(-pure)/es|stable|actual|full/array(/virtual)/flat-map
core-js(-pure)/es|stable|actual|full/array(/virtual)/for-each
core-js(-pure)/es|stable|actual|full/array(/virtual)/includes
core-js(-pure)/es|stable|actual|full/array(/virtual)/index-of
core-js(-pure)/es|stable|actual|full/array(/virtual)/iterator
core-js(-pure)/es|stable|actual|full/array(/virtual)/join
core-js(-pure)/es|stable|actual|full/array(/virtual)/keys
core-js(-pure)/es|stable|actual|full/array(/virtual)/last-index-of
core-js(-pure)/es|stable|actual|full/array(/virtual)/map
core-js(-pure)/es|stable|actual|full/array(/virtual)/push
core-js(-pure)/es|stable|actual|full/array(/virtual)/reduce
core-js(-pure)/es|stable|actual|full/array(/virtual)/reduce-right
core-js(-pure)/es|stable|actual|full/array(/virtual)/reverse
core-js(-pure)/es|stable|actual|full/array(/virtual)/slice
core-js(-pure)/es|stable|actual|full/array(/virtual)/some
core-js(-pure)/es|stable|actual|full/array(/virtual)/sort
core-js(-pure)/es|stable|actual|full/array(/virtual)/splice
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-reversed
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-sorted
core-js(-pure)/es|stable|actual|full/array(/virtual)/to-spliced
core-js(-pure)/es|stable|actual|full/array(/virtual)/unshift
core-js(-pure)/es|stable|actual|full/array(/virtual)/values
core-js(-pure)/es|stable|actual|full/array(/virtual)/with
```
[*Examples*](https://tinyurl.com/2oaa8x2x):
```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
[1, 2, 3, 4].findLast(isOdd); // => 3
[1, 2, 3, 4].findLastIndex(isOdd); // => 2
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]
[1, 2, 3].at(1); // => 2
[1, 2, 3].at(-1); // => 3
const sequence = [1, 2, 3];
sequence.toReversed(); // => [3, 2, 1]
sequence; // => [1, 2, 3]
const initialArray = [1, 2, 3, 4];
initialArray.toSpliced(1, 2, 5, 6, 7); // => [1, 5, 6, 7, 4]
initialArray; // => [1, 2, 3, 4]
const outOfOrder = [3, 1, 2];
outOfOrder.toSorted(); // => [1, 2, 3]
outOfOrder; // => [3, 1, 2]
const correctionNeeded = [1, 1, 3];
correctionNeeded.with(1, 2); // => [1, 2, 3]
correctionNeeded; // => [1, 1, 3]
```
#### ECMAScript: Iterator[⬆](#index)
Modules [`es.iterator.constructor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.constructor.js), [`es.iterator.drop`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.drop.js), [`es.iterator.every`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.every.js), [`es.iterator.filter`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.filter.js), [`es.iterator.find`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.find.js), [`es.iterator.flat-map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.flat-map.js), [`es.iterator.for-each`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.for-each.js), [`es.iterator.from`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.from.js), [`es.iterator.map`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.map.js), [`es.iterator.reduce`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.reduce.js), [`es.iterator.some`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.some.js), [`es.iterator.take`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.take.js), [`es.iterator.to-array`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.iterator.to-array.js)
```ts
class Iterator {
static from(iterable: Iterable<any> | Iterator<any>): Iterator<any>;
drop(limit: uint): Iterator<any>;
every(callbackfn: (value: any, counter: uint) => boolean): boolean;
filter(callbackfn: (value: any, counter: uint) => boolean): Iterator<any>;
find(callbackfn: (value: any, counter: uint) => boolean)): any;
flatMap(callbackfn: (value: any, counter: uint) => Iterable<any> | Iterator<any>): Iterator<any>;
forEach(callbackfn: (value: any, counter: uint) => void): void;
map(callbackfn: (value: any, counter: uint) => any): Iterator<any>;
reduce(callbackfn: (memo: any, value: any, counter: uint) => any, initialValue: any): any;
some(callbackfn: (value: any, counter: uint) => boolean): boolean;
take(limit: uint): Iterator<any>;
toArray(): Array<any>;
@@toStringTag: 'Iterator'
}
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es|stable|actual|full/iterator
core-js(-pure)/es|stable|actual|full/iterator/drop
core-js(-pure)/es|stable|actual|full/iterator/every
core-js(-pure)/es|stable|actual|full/iterator/filter
core-js(-pure)/es|stable|actual|full/iterator/find
core-js(-pure)/es|stable|actual|full/iterator/flat-map
core-js(-pure)/es|stable|actual|full/iterator/for-each
core-js(-pure)/es|stable|actual|full/iterator/from
core-js(-pure)/es|stable|actual|full/iterator/map
core-js(-pure)/es|stable|actual|full/iterator/reduce
core-js(-pure)/es|stable|actual|full/iterator/some
core-js(-pure)/es|stable|actual|full/iterator/take
core-js(-pure)/es|stable|actual|full/iterator/to-array
```
[Examples](https://tinyurl.com/249jw4e4):
```js
[1, 2, 3, 4, 5, 6, 7].values()
.drop(1)
.take(5)
.filter(it => it % 2)
.map(it => it ** 2)
.toArray(); // => [9, 25]
Iterator.from({
next: () => ({ done: Math.random() > 0.9, value: Math.random() * 10 | 0 }),
}).toArray(); // => [7, 6, 3, 0, 2, 8]
```
> [!WARNING]
> - For preventing prototype pollution, in the `pure` version, new `%IteratorPrototype%` methods are not added to the real `%IteratorPrototype%`, they are available only on wrappers - instead of `[].values().map(fn)` use `Iterator.from([]).map(fn)`.
#### ECMAScript: String and RegExp[⬆](#index)
The main part of `String` features: modules [`es.string.from-code-point`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.from-code-point.js), [`es.string.raw`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.raw.js), [`es.string.iterator`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.iterator.js), [`es.string.split`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.split.js), [`es.string.code-point-at`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.code-point-at.js), [`es.string.ends-with`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.ends-with.js), [`es.string.includes`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.includes.js), [`es.string.repeat`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.repeat.js), [`es.string.pad-start`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.pad-start.js), [`es.string.pad-end`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.pad-end.js), [`es.string.starts-with`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.starts-with.js), [`es.string.trim`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.trim.js), [`es.string.trim-start`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.trim-start.js), [`es.string.trim-end`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.trim-end.js), [`es.string.match-all`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.match-all.js), [`es.string.replace-all`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.replace-all.js), [`es.string.at-alternative`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.at-alternative.js), [`es.string.is-well-formed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.is-well-formed.js), [`es.string.to-well-formed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.to-well-formed.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/master/packages/core-js/modules/es.string.match.js), [`es.string.replace`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.replace.js), [`es.string.search`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.search.js) and [`es.string.split`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.split.js).
Annex B methods. Modules [`es.string.anchor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.anchor.js), [`es.string.big`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.big.js), [`es.string.blink`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.blink.js), [`es.string.bold`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.bold.js), [`es.string.fixed`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.fixed.js), [`es.string.fontcolor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.fontcolor.js), [`es.string.fontsize`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.fontsize.js), [`es.string.italics`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.italics.js), [`es.string.link`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.link.js), [`es.string.small`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.small.js), [`es.string.strike`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.strike.js), [`es.string.sub`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.sub.js), [`es.string.sup`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.sup.js), [`es.string.substr`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.string.substr.js), [`es.escape`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.escape.js) and [`es.unescape`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.unescape.js).
`RegExp` features: modules [`es.regexp.constructor`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.regexp.constructor.js), [`es.regexp.dot-all`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.regexp.dot-all.js), [`es.regexp.flags`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.regexp.flags.js), [`es.regexp.sticky`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.regexp.sticky.js) and [`es.regexp.test`](https://github.com/zloirock/core-js/blob/master/packages/core-js/modules/es.regexp.test.js).
```ts
class String {
static fromCodePoint(...codePoints: Array<number>): string;
static raw({ raw: Array<string> }, ...substitutions: Array<string>): string;
at(index: int): string;
includes(searchString: string, position?: number): boolean;
startsWith(searchString: string, position?: number): boolean;
endsWith(searchString: string, position?: number): boolean;
repeat(count: number): string;
padStart(length: number, fillStr?: string = ' '): string;
padEnd(length: number, fillStr?: string = ' '): string;
codePointAt(pos: number): number | void;
match(template: any): any; // ES2015+ fix for support @@match
matchAll(regexp: RegExp): Iterator;
replace(template: any, replacer: any): any; // ES2015+ fix for support @@replace
replaceAll(searchValue: string | RegExp, replaceString: string | (searchValue, index, this) => string): string;
search(template: any): any; // ES2015+ fix for support @@search
split(template: any, limit?: int): Array<string>;; // ES2015+ fix for support @@split, some fixes for old engines
trim(): string;
trimLeft(): string;
trimRight(): string;
trimStart(): string;
trimEnd(): string;
isWellFormed(): boolean;
toWellFormed(): string;
anchor(name: string): string;
big(): string;
blink(): string;
bold(): string;
fixed(): string;
fontcolor(color: string): string;
fontsize(size: any): string;
italics(): string;
link(url: string): string;
small(): string;
strike(): string;
sub(): string;
substr(start: int, length?: int): string;
sup(): string;
@@iterator(): Iterator<characters>;
}
class RegExp {
// support of sticky (`y`) flag, dotAll (`s`) flag, named capture groups, can alter flags
constructor(pattern: RegExp | string, flags?: string): RegExp;
exec(): Array<string | undefined> | null; // IE8 fixes
test(string: string): boolean; // delegation to `.exec`
toString(): string; // ES2015+ fix - generic
@@match(string: string): Array | null;
@@matchAll(string: string): Iterator;
@@replace(string: string, replaceValue: Function | string): string;
@@search(string: string): number;
@@split(string: string, limit: number): Array<string>;
readonly attribute dotAll: boolean; // IE9+
readonly attribute flags: string; // IE9+
readonly attribute sticky: boolean; // IE9+
}
function escape(string: string): string;
function unescape(string: string): string;
```
[*CommonJS entry points:*](#commonjs-api)
```
core-js(-pure)/es|stable|actual|full/string
core-js(-pure)/es|stable|actual|full/string/from-code-point
core-js(-pure)/es|stable|actual|full/string/raw
core-js/es|stable|actual|full/string/match
core-js/es|stable|actual|full/string/replace
core-js/es|stable|actual|full/string/search
core-js/es|stable|actual|full/string/split
core-js(-pure)/es|stable|actual/string(/virtual)/at
core-js(-pure)/es|stable|actual|full/string(/virtual)/code-point-at
core-js(-pure)/es|stable|actual|full/string(/virtual)/ends-with
core-js(-pure)/es|stable|actual|full/string(/virtual)/includes
core-js(-pure)/es|stable|actual|full/string(/virtual)/starts-with
core-js(-pure)/es|stable|actual|full/string(/virtual)/match-all
core-js(-pure)/es|stable|actual|full/string(/virtual)/pad-start
core-js(-pure)/es|stable|actual|full/string(/virtual)/pad-end
core-js(-pure)/es|stable|actual|full/string(/virtual)/repeat
core-js(-pure)/es|stable|actual|full/string(/virtual)/replace-all
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-start
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-end
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-left
core-js(-pure)/es|stable|actual|full/string(/virtual)/trim-right
core-js(-pure)/es|stable|actual|full/string(/virtual)/is-well-formed
core-js(-pure)/es|stable|actual|full/string(/virtual)/to-well-formed
core-js(-pure)/es|stable|actual|full/string(/virtual)/anchor
core-js(-pure)/es|stable|actual|full/string(/virtual)/big
core-js(-pure)/es|stable|actual|full/string(/virtual)/blink
core-js(-pure)/es|stable|actual|full/string(/virtual)/bold
core-js(-pure)/es|stable|actual|full/string(/virtual)/fixed
core-js(-pure)/es|stable|actual|full/string(/virtual)/fontcolor
core-js(-pure)/es|stable|actual|full/string(/virtual)/fontsize
core-js(-pure)/es|stable|actual|full/string(/virtual)/italics
core-js(-pure)/es|stable|actual|full/string(/virtual)/link
core-js(-pure)/es|stable|actual|full/string(/virtual)/small
core-js(-pure)/es|stable|actual|full/string(/virtual)/strike
core-js(-pure)/es|stable|actual|full/string(/virtual)/sub
core-js(-pure)/es|stable|actual|full/string(/virtual)/substr
core-js(-pure)/es|stable|actual|full/string(/virtual)/sup
core-js(-pure)/es|stable|actual|full/string(/virtual)/iterator
core-js/es|stable|actual|full/regexp
core-js/es|stable|actual|full/regexp/constructor
core-js/es|stable|actual|full/regexp/dot-all