- Fixed calling `onunhandledrejectionhandler` multiple times for one `Promise` chain, [#318](https://github.com/zloirock/core-js/issues/318)
- Forced replacement of `String#{padStart, padEnd}` in Safari 10 because of [a bug](https://bugs.webkit.org/show_bug.cgi?id=161944), [#280](https://github.com/zloirock/core-js/issues/280)
- Fixed `Array#@@iterator` in a very rare version of `WebKit`, [#236](https://github.com/zloirock/core-js/issues/236) and [#237](https://github.com/zloirock/core-js/issues/237)
- One more [#345](https://github.com/zloirock/core-js/issues/345)-related fix
##### 2.5.2 - 2017.12.09
-`MutationObserver` no longer used for microtask implementation in iOS Safari because of bug with scrolling, [#339](https://github.com/zloirock/core-js/issues/339)
- Fixed `JSON.stringify(undefined, replacer)` case in the wrapper from the `Symbol` polyfill, [#345](https://github.com/zloirock/core-js/issues/345)
-`Array()` calls changed to `new Array()` for V8 optimisation
##### 2.5.1 - 2017.09.01
- Updated `Promise#finally` per [tc39/proposal-promise-finally#37](https://github.com/tc39/proposal-promise-finally/issues/37)
- Optimized usage of some internal helpers for reducing size of `shim` version
- Updated `Object.getOwnPropertyDescriptors` to the [final version](https://tc39.github.io/ecma262/2017/#sec-object.getownpropertydescriptors) - it should not create properties if descriptors are `undefined`
- Updated the list of iterable DOM collections, [#249](https://github.com/zloirock/core-js/issues/249), added:
-`CSSStyleDeclaration#@@iterator`
-`CSSValueList#@@iterator`
-`ClientRectList#@@iterator`
-`DOMRectList#@@iterator`
-`DOMStringList#@@iterator`
-`DataTransferItemList#@@iterator`
-`FileList#@@iterator`
-`HTMLAllCollection#@@iterator`
-`HTMLCollection#@@iterator`
-`HTMLFormElement#@@iterator`
-`HTMLSelectElement#@@iterator`
-`MimeTypeArray#@@iterator`
-`NamedNodeMap#@@iterator`
-`PaintRequestList#@@iterator`
-`Plugin#@@iterator`
-`PluginArray#@@iterator`
-`SVGLengthList#@@iterator`
-`SVGNumberList#@@iterator`
-`SVGPathSegList#@@iterator`
-`SVGPointList#@@iterator`
-`SVGStringList#@@iterator`
-`SVGTransformList#@@iterator`
-`SourceBufferList#@@iterator`
-`TextTrackCueList#@@iterator`
-`TextTrackList#@@iterator`
-`TouchList#@@iterator`
- Updated stages of proposals:
- [`Object.getOwnPropertyDescriptors`](https://github.com/tc39/proposal-object-getownpropertydescriptors) to [stage 4 (ES2017)](https://tc39.github.io/ecma262/2017/#sec-object.getownpropertydescriptors)
- [String padding](https://github.com/tc39/proposal-string-pad-start-end) to [stage 4 (ES2017)](https://tc39.github.io/ecma262/2017/#sec-string.prototype.padend)
- [`global`](https://github.com/tc39/proposal-global) to [stage 3](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-09/sept-28.md#revisit-systemglobal--global)
- [String trimming](https://github.com/tc39/proposal-string-left-right-trim) to [stage 2](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-07/jul-27.md#10iic-trimstarttrimend)
- Updated typed arrays to the modern (ES2016+) arguments validation,
- Fixed compatibility with old version of Prototype.js, [#278](https://github.com/zloirock/core-js/issues/278), [#289](https://github.com/zloirock/core-js/issues/289)
-`Function#name` no longer cache the result for correct behaviour with inherited constructors, [#296](https://github.com/zloirock/core-js/issues/296)
- Added errors on incorrect context of collection methods, [#272](https://github.com/zloirock/core-js/issues/272)
- Fixed conversion typed array constructors to string, fix [#300](https://github.com/zloirock/core-js/issues/300)
- Fixed `Set#size` with debugger ReactNative for Android, [#297](https://github.com/zloirock/core-js/issues/297)
- Fixed an issue with Electron-based debugger, [#230](https://github.com/zloirock/core-js/issues/230)
- Fixed compatibility with incomplete third-party `WeakMap` polyfills, [#252](https://github.com/zloirock/core-js/pull/252)
- Added a fallback for `Date#toJSON` in engines without native `Date#toISOString`, [#220](https://github.com/zloirock/core-js/issues/220)
- Added support for Sphere Dispatch API, [#286](https://github.com/zloirock/core-js/pull/286)
- Seriously changed the coding style and the [ESLint config](https://github.com/zloirock/core-js/blob/master/.eslintrc.js)
- Updated many dev dependencies (`webpack`, `uglify`, etc)
- Some fixes for issues like [#159](https://github.com/zloirock/core-js/issues/159), [#186](https://github.com/zloirock/core-js/issues/186), [#194](https://github.com/zloirock/core-js/issues/194), [#207](https://github.com/zloirock/core-js/issues/207)
- Fixed behavior `Object.{getOwnPropertySymbols, getOwnPropertyDescriptor}` and `Object#propertyIsEnumerable` on `Object.prototype`
-`Reflect.construct` and `Reflect.apply` should throw an error if `argumentsList` argument is not an object, [#194](https://github.com/zloirock/core-js/issues/194)
##### 2.3.0 - 2016.04.24
- Added `asap` for enqueuing microtasks, [stage 0 proposal](https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-09/sept-25.md#510-globalasap-for-enqueuing-a-microtask)
- Added well-known symbol `Symbol.asyncIterator` for [stage 2 async iteration proposal](https://github.com/tc39/proposal-async-iteration)
- Added well-known symbol `Symbol.observable` for [stage 1 observables proposal](https://github.com/zenparsing/es-observable)
-`String#{padStart, padEnd}` returns original string if filler is empty string, [TC39 meeting notes](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-03/march-29.md#stringprototypepadstartpadend)
-`Object.values` and `Object.entries` moved to stage 4 from 3, [TC39 meeting notes](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-03/march-29.md#objectvalues--objectentries)
-`System.global` moved to stage 2 from 1, [TC39 meeting notes](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-03/march-29.md#systemglobal)
-`Map#toJSON` and `Set#toJSON` rejected and will be removed from the next major release, [TC39 meeting notes](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-03/march-31.md#mapprototypetojsonsetprototypetojson)
-`Error.isError` withdrawn and will be removed from the next major release, [TC39 meeting notes](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-03/march-29.md#erroriserror)
- Added fallback for `Function#name` on non-extensible functions and functions with broken `toString` conversion, [#193](https://github.com/zloirock/core-js/issues/193)
##### 2.2.2 - 2016.04.06
- Added conversion `-0` to `+0` to `Array#{indexOf, lastIndexOf}`, [ES2016 fix](https://github.com/tc39/ecma262/pull/316)
- Added fixes for some `Math` methods in Tor Browser
-`Array.{from, of}` no longer calls prototype setters
- Added workaround over Chrome DevTools strange behavior, [#186](https://github.com/zloirock/core-js/issues/186)
- Added `Object#__(define|lookup)[GS]etter__`, [annex B ES2017](https://github.com/tc39/ecma262/pull/381)
- Added `@@toPrimitive` methods to `Date` and `Symbol`
- Fixed `%TypedArray%#slice` in Edge ~ 13 (throws with `@@species` and wrapped / inherited constructor)
- Some other minor fixes
##### 2.1.5 - 2016.03.12
- Improved support NodeJS domains in `Promise#then`, [#180](https://github.com/zloirock/core-js/issues/180)
- Added fallback for `Date#toJSON` bug in Qt Script, [#173](https://github.com/zloirock/core-js/issues/173#issuecomment-193972502)
##### 2.1.4 - 2016.03.08
- Added fallback for `Symbol` polyfill in Qt Script, [#173](https://github.com/zloirock/core-js/issues/173)
- Added one more fallback for IE11 `Script Access Denied` error with iframes, [#165](https://github.com/zloirock/core-js/issues/165)
##### 2.1.3 - 2016.02.29
- Added fallback for [`es6-promise` package bug](https://github.com/stefanpenner/es6-promise/issues/169), [#176](https://github.com/zloirock/core-js/issues/176)
##### 2.1.2 - 2016.02.29
- Some minor `Promise` fixes:
- Browsers `rejectionhandled` event better HTML spec complaint
- Errors in unhandled rejection handlers should not cause any problems
- Fixed typo in feature detection
##### 2.1.1 - 2016.02.22
- Some `Promise` improvements:
- Feature detection:
- **Added detection unhandled rejection tracking support - now it's available everywhere**, [#140](https://github.com/zloirock/core-js/issues/140)
- Added detection `@@species` pattern support for completely correct subclassing
- Removed usage `Object.setPrototypeOf` from feature detection and noisy console message about it in FF
-`Promise.all` fixed for some very specific cases
##### 2.1.0 - 2016.02.09
- **API**:
- ES5 polyfills are split and logic, used in other polyfills, moved to internal modules
- **All entry point works in ES3 environment like IE8- without `core-js/(library/)es5`**
- **Added all missed single entry points for ES5 polyfills**
- Separated ES5 polyfills moved to the ES6 namespace. Why?
- Mainly, for prevent duplication features in different namespaces - logic of most required ES5 polyfills changed in ES6+:
- Already added changes for: `Object` statics - should accept primitives, new whitespaces lists in `String#trim`, `parse(Int|float)`, `RegExp#toString` logic, `String#split`, etc
- Should be changed in the future: `@@species` and `ToLength` logic in `Array` methods, `Date` parsing, `Function#bind`, etc
- Should not be changed only several features like `Array.isArray` and `Date.now`
- Some ES5 polyfills required for modern engines
- All old entry points should work fine, but in the next major release API can be changed
-`Object.getOwnPropertyDescriptors` moved to the stage 3, [January TC39 meeting](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-01/2016-01-28.md#objectgetownpropertydescriptors-to-stage-3-jordan-harband-low-priority-but-super-quick)
- Added `umd` option for [custom build process](https://github.com/zloirock/core-js#custom-build-from-external-scripts), [#169](https://github.com/zloirock/core-js/issues/169)
- Returned entry points for `Array` statics, removed in `2.0`, for compatibility with `babel``6` and for future fixes
- **Deprecated**:
-`Reflect.enumerate` deprecated and will be removed from the next major release, [January TC39 meeting](https://github.com/rwaldron/tc39-notes/blob/master/es7/2016-01/2016-01-28.md#5xix-revisit-proxy-enumerate---revisit-decision-to-exhaust-iterator)
- **New Features**:
- Added [`Reflect` metadata API](https://github.com/jonathandturner/decorators/blob/master/specs/metadata.md) as a pre-strawman feature, [#152](https://github.com/zloirock/core-js/issues/152):
-`Reflect.defineMetadata`
-`Reflect.deleteMetadata`
-`Reflect.getMetadata`
-`Reflect.getMetadataKeys`
-`Reflect.getOwnMetadata`
-`Reflect.getOwnMetadataKeys`
-`Reflect.hasMetadata`
-`Reflect.hasOwnMetadata`
-`Reflect.metadata`
- Implementation / fixes `Date#toJSON`
- Fixes for `parseInt` and `Number.parseInt`
- Fixes for `parseFloat` and `Number.parseFloat`
- Fixes for `RegExp#toString`
- Fixes for `Array#sort`
- Fixes for `Number#toFixed`
- Fixes for `Number#toPrecision`
- Additional fixes for `String#split` (`RegExp#@@split`)
- **Improvements**:
- Correct subclassing wrapped collections, `Number` and `RegExp` constructors with native class syntax
- Correct support `SharedArrayBuffer` and buffers from other realms in typed arrays wrappers
- Additional validations for `Object.{defineProperty, getOwnPropertyDescriptor}` and `Reflect.defineProperty`
- **Bug Fixes**:
- Fixed some cases `Array#lastIndexOf` with negative second argument
##### 2.0.3 - 2016.01.11
- Added fallback for V8 ~ Chrome 49 `Promise` subclassing bug causes unhandled rejection on feature detection, [#159](https://github.com/zloirock/core-js/issues/159)
- Added fix for very specific environments with global `window === null`
##### 2.0.2 - 2016.01.04
- Temporarily removed `length` validation from `Uint8Array` constructor wrapper. Reason - [bug in `ws` module](https://github.com/websockets/ws/pull/645) (-> `socket.io`) which passes to `Buffer` constructor -> `Uint8Array` float and uses [the `V8` bug](https://code.google.com/p/v8/issues/detail?id=4552) for conversion to int (by the spec should be thrown an error). [It creates problems for many people.](https://github.com/karma-runner/karma/issues/1768) I hope, it will be returned after fixing this bug in `V8`.
-`Object.assign` should be defined in the strict mode -> throw an error on extension non-extensible objects, [#154](https://github.com/zloirock/core-js/issues/154)
-`RegExp.escape` moved from the `es7` to the non-standard `core` namespace, [July TC39 meeting](https://github.com/rwaldron/tc39-notes/blob/master/es7/2015-07/july-28.md#62-regexpescape) - too slow, but it's condition of stability, [#116](https://github.com/zloirock/core-js/issues/116)
- Added basic support [`rejectionHandled` event / `onrejectionhandled` handler](https://github.com/zloirock/core-js#unhandled-rejection-tracking) to the polyfill
- Removed usage `@@species` from `Promise.{all, race}`, [November TC39 meeting](https://github.com/rwaldron/tc39-notes/tree/master/es7/2015-11/nov-18.md#conclusionresolution-2)
- Some improvements [collections polyfills](https://github.com/zloirock/core-js#ecmascript-6-collections)
- Renamed `String#{padLeft, padRight}` -> [`String#{padStart, padEnd}`](https://github.com/zloirock/core-js#ecmascript-7-proposals), [proposal](https://github.com/tc39/proposal-string-pad-start-end), [November TC39 meeting](https://github.com/rwaldron/tc39-notes/tree/master/es7/2015-11/nov-17.md#conclusionresolution-2) (they want to rename it on each meeting?O_o), [#132](https://github.com/zloirock/core-js/issues/132)
- Added [`String#{trimStart, trimEnd}` as aliases for `String#{trimLeft, trimRight}`](https://github.com/zloirock/core-js#ecmascript-7-proposals), [proposal](https://github.com/sebmarkbage/ecmascript-string-left-right-trim), [November TC39 meeting](https://github.com/rwaldron/tc39-notes/tree/master/es7/2015-11/nov-17.md#conclusionresolution-2)
- Added [annex B HTML methods](https://github.com/zloirock/core-js#ecmascript-6-string) - ugly, but also [the part of the spec](http://www.ecma-international.org/ecma-262/6.0/#sec-string.prototype.anchor)
- Added little fix for [`Date#toString`](https://github.com/zloirock/core-js#ecmascript-6-date) - `new Date(NaN).toString()` [should be `'Invalid Date'`](http://www.ecma-international.org/ecma-262/6.0/#sec-todatestring)
- Added [`{keys, values, entries, @@iterator}` methods to DOM collections](https://github.com/zloirock/core-js#iterable-dom-collections) which should have [iterable interface](https://heycam.github.io/webidl/#idl-iterable) or should be [inherited from `Array`](https://heycam.github.io/webidl/#LegacyArrayClass) - `NodeList`, `DOMTokenList`, `MediaList`, `StyleSheetList`, `CSSRuleList`.
- Removed Mozilla `Array` generics - [deprecated and will be removed from FF](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array#Array_generic_methods), [looks like strawman is dead](http://wiki.ecmascript.org/doku.php?id=strawman:array_statics), available [alternative shim](https://github.com/plusdude/array-generics)
- Added entry points for [virtual methods](https://github.com/zloirock/core-js#commonjs-and-prototype-methods-without-global-namespace-pollution)
- Added entry points for [stages proposals](https://github.com/zloirock/core-js#ecmascript-7-proposals)
- Some other minor changes
- [Custom build from external scripts](https://github.com/zloirock/core-js#custom-build-from-external-scripts) moved to the separate package for preventing problems with dependencies
- Changed `$` prefix for internal modules file names because Team Foundation Server does not support it, [#129](https://github.com/zloirock/core-js/issues/129)
- Additional fix for `SameValueZero` in V8 ~ Chromium 39-42 collections
- Additional fix for FF27 `Array` iterator
- Removed usage shortcuts for `arguments` object - old WebKit bug, [#150](https://github.com/zloirock/core-js/issues/150)
* Fixed some problems related old V8 bug `Object('a').propertyIsEnumerable(0) // => false`, for example, `Object.assign({}, 'qwe')` from the last release
* Fixed `.name` property and `Function#toString` conversion some polyfilled methods
* Replaced fix `JSON.stringify` + `Symbol` behavior from `.toJSON` method to wrapping `JSON.stringify` - little more correct, [compat-table/642](https://github.com/kangax/compat-table/pull/642)
* Fixed typo which broke tasks scheduler in WebWorkers in old FF, [#114](https://github.com/zloirock/core-js/pull/114)
* Added correct [`IsRegExp`](http://www.ecma-international.org/ecma-262/6.0/#sec-isregexp) logic to [`String#{includes, startsWith, endsWith}`](https://github.com/zloirock/core-js/#ecmascript-6-string) and [`RegExp` constructor](https://github.com/zloirock/core-js/#ecmascript-6-regexp), `@@match` case, [example](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/match#Disabling_the_isRegExp_check)
* Updated [`String#leftPad`](https://github.com/zloirock/core-js/#ecmascript-7-proposals) [with proposal](https://github.com/ljharb/proposal-string-pad-left-right/issues/6): string filler truncated from the right side
* Replaced V8 [`Object.assign`](https://github.com/zloirock/core-js/#ecmascript-6-object) - its properties order not only [incorrect](https://github.com/sindresorhus/object-assign/issues/22), it is non-deterministic and it causes some problems
* Fixed behavior with deleted in getters properties for `Object.{`[`assign`](https://github.com/zloirock/core-js/#ecmascript-6-object)`, `[`entries, values`](https://github.com/zloirock/core-js/#ecmascript-7-proposals)`}`, [example](http://goo.gl/iQE01c)
* Fixed [`Math.sinh`](https://github.com/zloirock/core-js/#ecmascript-6-math) with very small numbers in V8 near Chromium 38
* Fixed support Node.js domains in [`Promise`](https://github.com/zloirock/core-js/#ecmascript-6-promise), [#103](https://github.com/zloirock/core-js/issues/103)
* Added `toJSON` method to [`Symbol`](https://github.com/zloirock/core-js/#ecmascript-6-symbol) polyfill and to MS Edge implementation for expected `JSON.stringify` result w/o patching this method
* Replaced [`Reflect.construct`](https://github.com/zloirock/core-js/#ecmascript-6-reflect) implementations w/o correct support third argument
* Fixed `global` detection with changed `document.domain` in ~IE8, [#100](https://github.com/zloirock/core-js/issues/100)
* Added [string trim functions](#ecmascript-7-proposals) - [proposal](https://github.com/sebmarkbage/ecmascript-string-left-right-trim), defacto standard - required only for IE11- and fixed for some old engines:
* [`String#trim`](https://github.com/zloirock/core-js/#ecmascript-6-string) fixed for some engines by es6 spec and moved from `es5` to single `es6` module
* Caps for `freeze`-family `Object` methods moved from `es5` to `es6` namespace and joined with [es6 wrappers](https://github.com/zloirock/core-js/#ecmascript-6-object)
* Some fixes for final MS Edge, replaced broken native `Reflect.defineProperty`
* Some minor fixes and optimizations
* Changed compression `client/*.min.js` options for safe `Function#name` and `Function#length`, should be fixed [#92](https://github.com/zloirock/core-js/issues/92)
* Moved `$for` to [separate library](https://github.com/zloirock/forof). This work for syntax - `for-of` loop and comprehensions
* Moved `Date#{format, formatUTC}` to [separate library](https://github.com/zloirock/dtf). Standard way for this - `ECMA-402`
* Removed `Math` methods from `Number.prototype`. Slight sugar for simple `Math` methods calling
* Removed `{Array#, Array, Dict}.turn`
* Removed `core.global`
* Uses `ToNumber` instead of `ToLength` in [`Number Iterator`](https://github.com/zloirock/core-js/#number-iterator), `Array.from(2.5)` will be `[0, 1, 2]` instead of `[0, 1]`
* Updated [`RegExp.escape`](https://github.com/zloirock/core-js/#ecmascript-7-proposals) to the [latest proposal](https://github.com/benjamingr/RexExp.escape)
* Fixed conflict with webpack dev server + IE buggy behavior
* Wrapped `Function#toString` for correct work wrapped methods / constructors with methods similar to the [`lodash` `isNative`](https://github.com/lodash/lodash/issues/1197)
* Added proto versions of methods to export object in `default` version for consistency with `library` version
* Added [support DOM collections](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice#Streamlining_cross-browser_behavior) to IE8- `Array#slice`
* Removed non-standard methods `Object#[_]` and `Function#only` - they solves syntax problems, but now in compilers available arrows and ~~in near future will be available~~ [available](http://babeljs.io/blog/2015/05/14/function-bind/) [bind syntax](https://github.com/zenparsing/es-function-bind)
* Added support ES3 environment (ES5 polyfill) to **all** default versions - size increases slightly (+ ~4kb w/o gzip), many issues disappear, if you don't need it - [simply include only required namespaces / features / modules](https://github.com/zloirock/core-js/#commonjs)
* Removed [abstract references](https://github.com/zenparsing/es-abstract-refs) support - proposal has been superseded =\
* [`$for.isIterable` -> `core.isIterable`, `$for.getIterator` -> `core.getIterator`](https://github.com/zloirock/core-js/#ecmascript-6-iterators), temporary available in old namespace
* Iterators moved to [`es6`](https://github.com/zloirock/core-js/#ecmascript-6) and [`es6.collections`](https://github.com/zloirock/core-js/#ecmascript-6-collections) modules
