# core-js
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Modular compact standard library for JavaScript. Includes polyfills for [ECMAScript 5](#ecmascript-5), [ECMAScript 6](#ecmascript-6): [symbols](#ecmascript-6-symbol), [collections](#ecmascript-6-collections), [iterators](#ecmascript-6-iterators), [promises](#ecmascript-6-promise), [ECMAScript 7 proposals](#ecmascript-7); [setImmediate](#setimmediate), [array generics](#mozilla-javascript-array-generics). Some additional features such as [dictionaries](#dict) or [extended partial application](#partial-application). You can require only standardized features polyfills, use features without global namespace pollution or create a custom build.
[Example](http://goo.gl/mfHYm2):
```javascript
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
'*'.repeat(10); // => '**********'
Promise.resolve(32).then(log); // => 32
setImmediate(log, 42); // => 42
```
[Without global namespace pollution](http://goo.gl/WBhs43):
```javascript
var core = require('core-js/library'); // With a modular system, otherwise use global `core`
core.Array.from(new core.Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
core.String.repeat('*', 10); // => '**********'
core.Promise.resolve(32).then(core.log); // => 32
core.setImmediate(core.log, 42); // => 42
```
- [Usage](#usage)
- [Basic](#basic)
- [CommonJS](#commonjs)
- [Custom build](#custom-build)
- [API](#api)
- [ECMAScript 5](#ecmascript-5)
- [ECMAScript 6](#ecmascript-6)
- [ECMAScript 6: Object](#ecmascript-6-object)
- [ECMAScript 6: Function](#ecmascript-6-function)
- [ECMAScript 6: Array](#ecmascript-6-array)
- [ECMAScript 6: String](#ecmascript-6-string)
- [ECMAScript 6: RegExp](#ecmascript-6-regexp)
- [ECMAScript 6: Number](#ecmascript-6-number)
- [ECMAScript 6: Math](#ecmascript-6-math)
- [ECMAScript 6: Symbol](#ecmascript-6-symbol)
- [ECMAScript 6: Collections](#ecmascript-6-collections)
- [ECMAScript 6: Iterators](#ecmascript-6-iterators)
- [ECMAScript 6: Promise](#ecmascript-6-promise)
- [ECMAScript 6: Reflect](#ecmascript-6-reflect)
- [ECMAScript 7](#ecmascript-7)
- [Mozilla JavaScript: Array generics](#mozilla-javascript-array-generics)
- [setTimeout / setInterval](#settimeout--setinterval)
- [setImmediate](#setimmediate)
- [console](#console)
- [Object](#object)
- [Dict](#dict)
- [Partial application](#partial-application)
- [Number Iterator](#number-iterator)
- [Escaping HTML](#escaping-html)
- [delay](#delay)
- [Missing polyfills](#missing-polyfills)
- [Changelog](#changelog)
## Usage
### Basic
```
npm i core-js
bower install core.js
```
```javascript
// Default
require('core-js');
// Without global namespace pollution
var core = require('core-js/library');
// Shim only
require('core-js/shim');
```
If you need complete build for browser, use builds from `core-js/client` path: [default](https://raw.githack.com/zloirock/core-js/master/client/core.min.js), [without global namespace pollution](https://raw.githack.com/zloirock/core-js/master/client/library.min.js), [shim only](https://raw.githack.com/zloirock/core-js/master/client/shim.min.js).
Warning: if you uses `core-js` with the extension of native objects, require all needed `core-js` modules at the beginning of entry point of your application, otherwise maybe conflicts.
### CommonJS
You can require only needed modules.
```js
require('core-js/es5'); // if you need support IE8-
require('core-js/fn/set');
require('core-js/fn/array/from');
require('core-js/fn/array/find-index');
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
[1, 2, NaN, 3, 4].findIndex(isNaN); // => 2
// or, w/o global namespace pollution:
var core = require('core-js/library/es5'); // if you need support IE8-
var Set = require('core-js/library/fn/set');
var from = require('core-js/library/fn/array/from');
var findIndex = require('core-js/library/fn/array/find-index');
from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
findIndex([1, 2, NaN, 3, 4], isNaN); // => 2
```
Available entry points for methods / constructors, as above examples, excluding features from [`es5`](#ecmascript-5) module (this module requires completely in ES3 environment before all other modules).
Available namespaces: for example, `core-js/es6/array` (`core-js/library/es6/array`) contains all [ES6 `Array` features](#ecmascript-6-array), `core-js/es6` (`core-js/library/es6`) contains all ES6 features.
### Custom build
```
npm i core-js && cd node_modules/core-js && npm i
npm run grunt build:core.dict,es6 -- --blacklist=es6.promise,es6.math --library=on --path=custom uglify
```
Where `core.dict` and `es6` are modules (namespaces) names, which will be added to the build, `es6.promise` and `es6.math` are modules (namespaces) names, which will be excluded from the build, `--library=on` is flag for build without global namespace pollution and `custom` is target file name.
Available namespaces: for example, `es6.array` contains [ES6 `Array` features](#ecmascript-6-array), `es6` contains all modules whose names start with `es6`.
Available custom build from js code (required `webpack`):
```js
require('core-js/build')({
modules: ['es6', 'core.dict'], // modules / namespaces
blacklist: ['es6.reflect'], // blacklist of modules / namespaces
library: false, // flag for build without global namespace pollution
}, function(err, code){ // callback
// ...
});
```
## API:
### ECMAScript 5
Module [`es5`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es5.js), nothing new - without examples.
```javascript
Object
.create(proto | null, descriptors?) -> object
.getPrototypeOf(object) -> proto | null
.defineProperty(target, key, desc) -> target, cap for ie8-
.defineProperties(target, descriptors) -> target, cap for ie8-
.getOwnPropertyDescriptor(object, key) -> desc
.getOwnPropertyNames(object) -> array
.keys(object) -> array
Array
.isArray(var) -> bool
#slice(start?, end?) -> array, fix for ie7-
#join(string = ',') -> string, fix for ie7-
#indexOf(var, from?) -> int
#lastIndexOf(var, from?) -> int
#every(fn(val, index, @), that) -> bool
#some(fn(val, index, @), that) -> bool
#forEach(fn(val, index, @), that) -> void
#map(fn(val, index, @), that) -> array
#filter(fn(val, index, @), that) -> array
#reduce(fn(memo, val, index, @), memo?) -> var
#reduceRight(fn(memo, val, index, @), memo?) -> var
Function
#bind(object, ...args) -> boundFn(...args)
Date
.now() -> int
#toISOString() -> string
```
Some features moved to [another modules / namespaces](#ecmascript-6), but available as part of `es5` namespace too:
```js
Object
.seal(object) -> object, cap for ie8-
.freeze(object) -> object, cap for ie8-
.preventExtensions(object) -> object, cap for ie8-
.isSealed(object) -> bool, cap for ie8-
.isFrozen(object) -> bool, cap for ie8-
.isExtensible(object) -> bool, cap for ie8-
String
#trim() -> str
```
### ECMAScript 6
#### ECMAScript 6: Object
Modules [`es6.object.assign`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.assign.js), [`es6.object.is`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.is.js), [`es6.object.set-prototype-of`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.set-prototype-of.js) and [`es6.object.to-string`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.to-string.js).
```javascript
Object
.assign(target, ...src) -> target
.is(a, b) -> bool
.setPrototypeOf(target, proto | null) -> target (required __proto__ - IE11+)
#toString() -> string, ES6 fix: @@toStringTag support
```
[Example](http://goo.gl/VzmY3j):
```javascript
var foo = {q: 1, w: 2}
, bar = {e: 3, r: 4}
, 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(){}
function Child(){}
Object.setPrototypeOf(Child.prototype, Parent.prototype);
new Child instanceof Child; // => true
new Child instanceof Parent; // => true
var O = {};
O[Symbol.toStringTag] = 'Foo';
'' + O; // => '[object Foo]'
```
In ES6 most `Object` static methods should work with primitives. Modules [`es6.object.freeze`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.freeze.js), [`es6.object.seal`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.seal.js), [`es6.object.prevent-extensions`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.prevent-extensions.js), [`es6.object.is-frozen`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.is-frozen.js), [`es6.object.is-sealed`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.is-sealed.js), [`es6.object.is-extensible`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.is-extensible.js), [`es6.object.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.get-own-property-descriptor.js), [`es6.object.get-prototype-of`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.get-prototype-of.js), [`es6.object.keys`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.keys.js), [`es6.object.get-own-property-names`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.object.get-own-property-names.js).
```javascript
Object
.freeze(var) -> var
.seal(var) -> var
.preventExtensions(var) -> var
.isFrozen(var) -> bool
.isSealed(var) -> bool
.isExtensible(var) -> bool
.getOwnPropertyDescriptor(var, key) -> desc | undefined
.getPrototypeOf(var) -> object | null
.keys(var) -> array
.getOwnPropertyNames(var) -> array
```
[Example](http://goo.gl/35lPSi):
```javascript
Object.keys('qwe'); // => ['0', '1', '2']
Object.getPrototypeOf('qwe') === String.prototype; // => true
```
#### ECMAScript 6: Function
Modules [`es6.function.name`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.function.name.js) and [`es6.function.has-instance`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.function.has-instance.js).
```javascript
Function
#name -> string (IE9+)
#@@hasInstance(var) -> bool
```
[Example](http://goo.gl/zqu3Wp):
```javascript
(function foo(){}).name // => 'foo'
```
#### ECMAScript 6: Array
Modules [`es6.array.from`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.from.js), [`es6.array.of`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.of.js), [`es6.array.copy-within`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.copy-within.js), [`es6.array.fill`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.fill.js), [`es6.array.find`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.find.js) and [`es6.array.find-index`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.find-index.js).
```javascript
Array
.from(iterable | array-like, mapFn(val, index)?, that) -> array
.of(...args) -> array
#copyWithin(target = 0, start = 0, end = @length) -> @
#fill(val, start = 0, end = @length) -> @
#find(fn(val, index, @), that) -> val
#findIndex(fn(val, index, @), that) -> index
#@@unscopables -> object (cap)
```
[Example](http://goo.gl/nxmJTe):
```javascript
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', function(it){
return it * it;
}); // => [1, 4, 9]
Array.of(1); // => [1]
Array.of(1, 2, 3); // => [1, 2, 3]
function isOdd(val){
return val % 2;
}
[4, 8, 15, 16, 23, 42].find(isOdd); // => 15
[4, 8, 15, 16, 23, 42].findIndex(isOdd); // => 2
[4, 8, 15, 16, 23, 42].find(isNaN); // => undefined
[4, 8, 15, 16, 23, 42].findIndex(isNaN); // => -1
Array(5).fill(42); // => [42, 42, 42, 42, 42]
[1, 2, 3, 4, 5].copyWithin(0, 3); // => [4, 5, 3, 4, 5]
```
#### ECMAScript 6: String
Modules [`es6.string.from-code-point`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.from-code-point.js), [`es6.string.raw`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.raw.js), [`es6.string.code-point-at`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.code-point-at.js), [`es6.string.ends-with`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.ends-with.js), [`es6.string.includes`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.includes.js), [`es6.string.repeat`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.repeat.js), [`es6.string.starts-with`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.starts-with.js) and [`es6.string.trim`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.trim.js).
```javascript
String
.fromCodePoint(...codePoints) -> str
.raw({raw}, ...substitutions) -> str
#includes(str, from?) -> bool
#startsWith(str, from?) -> bool
#endsWith(str, from?) -> bool
#repeat(num) -> str
#codePointAt(pos) -> uint
#trim() -> str, ES6 fix
```
[Examples](http://goo.gl/RMyFBo):
```javascript
'foobarbaz'.includes('bar'); // => true
'foobarbaz'.includes('bar', 4); // => false
'foobarbaz'.startsWith('foo'); // => true
'foobarbaz'.startsWith('bar', 3); // => true
'foobarbaz'.endsWith('baz'); // => true
'foobarbaz'.endsWith('bar', 6); // => true
'string'.repeat(3); // => 'stringstringstring'
'𠮷'.codePointAt(0); // => 134071
String.fromCodePoint(97, 134071, 98); // => 'a𠮷b'
var name = 'Bob';
String.raw`Hi\n${name}!`; // => 'Hi\\nBob!' (ES6 template string syntax)
String.raw({raw: 'test'}, 0, 1, 2); // => 't0e1s2t'
```
#### ECMAScript 6: RegExp
Modules [`es6.regexp.constructor`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.constructor.js) and [`es6.regexp.flags`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.flags.js).
Support well-known [symbols](#ecmascript-6-symbol) `@@match`, `@@replace`, `@@search` and `@@split`, modules [`es6.regexp.match`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.match.js), [`es6.regexp.replace`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.replace.js), [`es6.regexp.search`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.search.js) and [`es6.regexp.split`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.regexp.split.js).
```
String
#match(tpl) -> var, ES6 fix for support @@match
#replace(tpl, replacer) -> var, ES6 fix for support @@replace
#search(tpl) -> var, ES6 fix for support @@search
#split(tpl, limit) -> var, ES6 fix for support @@split
[new] RegExp(pattern, flags?) -> regexp, ES6 fix: can alter flags (IE9+)
#flags -> str (IE9+)
#@@match(str) -> array | null
#@@replace(str, replacer) -> string
#@@search(str) -> index
#@@split(str, limit) -> array
```
[Examples](http://goo.gl/vLV603):
```javascript
RegExp(/./g, 'm'); // => /./m
/foo/.flags; // => ''
/foo/gim.flags; // => 'gim'
'foo'.match({[Symbol.match]: _ => 1}); // => 1
'foo'.replace({[Symbol.replace]: _ => 2}); // => 2
'foo'.search({[Symbol.search]: _ => 3}); // => 3
'foo'.split({[Symbol.split]: _ => 4}); // => 4
```
#### ECMAScript 6: Number
Module [`es6.number.constructor`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.constructor.js). `Number` constructor support binary and octal literals, [example](http://goo.gl/jRd6b3):
```javascript
Number('0b1010101'); // => 85
Number('0o7654321'); // => 2054353
```
`Number`: modules [`es6.number.epsilon`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.epsilon.js), [`es6.number.is-finite`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.is-finite.js), [`es6.number.is-integer`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.is-integer.js), [`es6.number.is-nan`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.is-nan.js), [`es6.number.is-safe-integer`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.is-safe-integer.js), [`es6.number.max-safe-integer`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.max-safe-integer.js), [`es6.number.min-safe-integer`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.min-safe-integer.js), [`es6.number.parse-float`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.parse-float.js), [`es6.number.parse-int`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.number.parse-int.js).
```javascript
[new] Number(var) -> number | number object
.EPSILON -> num
.isFinite(num) -> bool
.isInteger(num) -> bool
.isNaN(num) -> bool
.isSafeInteger(num) -> bool
.MAX_SAFE_INTEGER -> int
.MIN_SAFE_INTEGER -> int
.parseFloat(str) -> num
.parseInt(str) -> int
```
#### ECMAScript 6: Math
`Math`: modules [`es6.math.acosh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.acosh.js), [`es6.math.asinh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.asinh.js), [`es6.math.atanh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.atanh.js), [`es6.math.cbrt`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.cbrt.js), [`es6.math.clz32`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.clz32.js), [`es6.math.cosh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.cosh.js), [`es6.math.expm1`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.expm1.js), [`es6.math.fround`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.fround.js), [`es6.math.hypot`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.hypot.js), [`es6.math.imul`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.imul.js), [`es6.math.log10`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.log10.js), [`es6.math.log1p`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.log1p.js), [`es6.math.log2`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.log2.js), [`es6.math.sign`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.sign.js), [`es6.math.sinh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.sinh.js), [`es6.math.tanh`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.tanh.js), [`es6.math.trunc`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.math.trunc.js).
```javascript
Math
.acosh(num) -> num
.asinh(num) -> num
.atanh(num) -> num
.cbrt(num) -> num
.clz32(num) -> uint
.cosh(num) -> num
.expm1(num) -> num
.fround(num) -> num
.hypot(...args) -> num
.imul(num, num) -> int
.log1p(num) -> num
.log10(num) -> num
.log2(num) -> num
.sign(num) -> 1 | -1 | 0 | -0 | NaN
.sinh(num) -> num
.tanh(num) -> num
.trunc(num) -> num
```
#### ECMAScript 6: Symbol
Module [`es6.symbol`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.symbol.js).
```javascript
Symbol(description?) -> symbol
.hasInstance -> @@hasInstance
.isConcatSpreadable -> @@isConcatSpreadable
.iterator -> @@iterator
.match -> @@match
.replace -> @@replace
.search -> @@search
.species -> @@species
.split -> @@split
.toPrimitive -> @@toPrimitive
.toStringTag -> @@toStringTag
.unscopables -> @@unscopables
.for(key) -> symbol
.keyFor(symbol) -> key
.useSimple() -> void
.useSetter() -> void
Object
.getOwnPropertySymbols(object) -> array
```
Also wrapped some `Object` methods for correct work with `Symbol` polyfill.
```js
Object
.create(proto | null, descriptors?) -> object
.defineProperty(target, key, desc) -> target
.defineProperties(target, descriptors) -> target
.getOwnPropertyDescriptor(var, key) -> desc | undefined
.getOwnPropertyNames(var) -> array
#propertyIsEnumerable(key) -> bool
```
[Basic example](http://goo.gl/BbvWFc):
```javascript
var Person = (function(){
var NAME = Symbol('name');
function Person(name){
this[NAME] = name;
}
Person.prototype.getName = function(){
return this[NAME];
};
return Person;
})();
var person = new Person('Vasya');
log(person.getName()); // => 'Vasya'
log(person['name']); // => undefined
log(person[Symbol('name')]); // => undefined, symbols are uniq
for(var key in person)log(key); // => only 'getName', symbols are not enumerable
```
`Symbol.for` & `Symbol.keyFor` [example](http://goo.gl/0pdJjX):
```javascript
var symbol = Symbol.for('key');
symbol === Symbol.for('key'); // true
Symbol.keyFor(symbol); // 'key'
```
[Example](http://goo.gl/mKVOQJ) with methods for getting own object keys:
```javascript
var O = {a: 1};
Object.defineProperty(O, 'b', {value: 2});
O[Symbol('c')] = 3;
Object.keys(O); // => ['a']
Object.getOwnPropertyNames(O); // => ['a', 'b']
Object.getOwnPropertySymbols(O); // => [Symbol(c)]
Reflect.ownKeys(O); // => ['a', 'b', Symbol(c)]
```
#### Caveats when using `Symbol` polyfill:
* We can't add new primitive type, `Symbol` returns object.
* `Symbol.for` and `Symbol.keyFor` can't be shimmed cross-realm.
* By default, to hide the keys, `Symbol` polyfill defines setter in `Object.prototype`. For this reason, uncontrolled creation of symbols can cause memory leak and the `in` operator is not working correctly with `Symbol` polyfill: `Symbol() in {} // => true`.
You can disable defining setters in `Object.prototype`. [Example](http://goo.gl/N5UD7J):
```javascript
Symbol.useSimple();
var s1 = Symbol('s1')
, o1 = {};
o1[s1] = true;
for(var key in o1)log(key); // => 'Symbol(s1)_t.qamkg9f3q', w/o native Symbol
Symbol.useSetter();
var s2 = Symbol('s2')
, o2 = {};
o2[s2] = true;
for(var key in o2)log(key); // nothing
```
* Currently, `core-js` not adds setters to `Object.prototype` for well-known symbols for correct work something like `Symbol.iterator in foo`. It can cause problems with their enumerability.
#### ECMAScript 6: Collections
`core-js` uses native collections in most case, just fixes methods / constructor, if it's required, and in old environment uses fast polyfill (O(1) lookup).
#### Map
Module [`es6.map`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.map.js). About iterators from this module [here](#ecmascript-6-iterators).
```javascript
new Map(iterable (entries) ?) -> map
#clear() -> void
#delete(key) -> bool
#forEach(fn(val, key, @), that) -> void
#get(key) -> val
#has(key) -> bool
#set(key, val) -> @
#size -> uint
```
[Example](http://goo.gl/RDbROF):
```javascript
var a = [1];
var map = new Map([['a', 1], [42, 2]]);
map.set(a, 3).set(true, 4);
log(map.size); // => 4
log(map.has(a)); // => true
log(map.has([1])); // => false
log(map.get(a)); // => 3
map.forEach(function(val, key){
log(val); // => 1, 2, 3, 4
log(key); // => 'a', 42, [1], true
});
map.delete(a);
log(map.size); // => 3
log(map.get(a)); // => undefined
log(Array.from(map)); // => [['a', 1], [42, 2], [true, 4]]
```
#### Set
Module [`es6.set`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.set.js). About iterators from this module [here](#ecmascript-6-iterators).
```javascript
new Set(iterable?) -> set
#add(key) -> @
#clear() -> void
#delete(key) -> bool
#forEach(fn(el, el, @), that) -> void
#has(key) -> bool
#size -> uint
```
[Example](http://goo.gl/7XYya3):
```javascript
var set = new Set(['a', 'b', 'a', 'c']);
set.add('d').add('b').add('e');
log(set.size); // => 5
log(set.has('b')); // => true
set.forEach(function(it){
log(it); // => 'a', 'b', 'c', 'd', 'e'
});
set.delete('b');
log(set.size); // => 4
log(set.has('b')); // => false
log(Array.from(set)); // => ['a', 'c', 'd', 'e']
```
#### WeakMap
Module [`es6.weak-map`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.weak-map.js).
```javascript
new WeakMap(iterable (entries) ?) -> weakmap
#delete(key) -> bool
#get(key) -> val
#has(key) -> bool
#set(key, val) -> @
```
[Example](http://goo.gl/SILXyw):
```javascript
var a = [1]
, b = [2]
, c = [3];
var wmap = new WeakMap([[a, 1], [b, 2]]);
wmap.set(c, 3).set(b, 4);
log(wmap.has(a)); // => true
log(wmap.has([1])); // => false
log(wmap.get(a)); // => 1
wmap.delete(a);
log(wmap.get(a)); // => undefined
// Private properties store:
var Person = (function(){
var names = new WeakMap;
function Person(name){
names.set(this, name);
}
Person.prototype.getName = function(){
return names.get(this);
};
return Person;
})();
var person = new Person('Vasya');
log(person.getName()); // => 'Vasya'
for(var key in person)log(key); // => only 'getName'
```
#### WeakSet
Module [`es6.weak-set`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.weak-set.js).
```javascript
new WeakSet(iterable?) -> weakset
#add(key) -> @
#delete(key) -> bool
#has(key) -> bool
```
[Example](http://goo.gl/TdFbEx):
```javascript
var a = [1]
, b = [2]
, c = [3];
var wset = new WeakSet([a, b, a]);
wset.add(c).add(b).add(c);
log(wset.has(b)); // => true
log(wset.has([2])); // => false
wset.delete(b);
log(wset.has(b)); // => false
```
#### Caveats when using collections polyfill:
* Frozen objects as collection keys are supported, but not recomended - it's slow (O(n) instead of O(1)) and, for weak-collections, leak.
* Weak-collections polyfill stores values as hidden properties of keys. It works correct and not leak in most cases. However, it is desirable to store a collection longer than its keys.
#### ECMAScript 6: Iterators
Modules [`es6.string.iterator`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.string.iterator.js) and [`es6.array.iterator`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.array.iterator.js):
```javascript
String
#@@iterator() -> iterator
Array
#values() -> iterator
#keys() -> iterator
#entries() -> iterator (entries)
#@@iterator() -> iterator
Arguments
#@@iterator() -> iterator (available only in core-js methods)
```
Modules [`es6.map`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.map.js) and [`es6.set`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.set.js):
```javascript
Map
#values() -> iterator
#keys() -> iterator
#entries() -> iterator (entries)
#@@iterator() -> iterator (entries)
Set
#values() -> iterator
#keys() -> iterator
#entries() -> iterator (entries)
#@@iterator() -> iterator
```
Module [`web.dom.iterable`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/web.dom.iterable.js):
```javascript
NodeList
#@@iterator() -> iterator
```
[Example](http://goo.gl/nzHVQF):
```javascript
var string = 'a𠮷b';
for(var val of string)log(val); // => 'a', '𠮷', 'b'
var array = ['a', 'b', 'c'];
for(var val of array)log(val); // => 'a', 'b', 'c'
for(var val of array.values())log(val); // => 'a', 'b', 'c'
for(var key of array.keys())log(key); // => 0, 1, 2
for(var [key, val] of array.entries()){
log(key); // => 0, 1, 2
log(val); // => 'a', 'b', 'c'
}
var map = new Map([['a', 1], ['b', 2], ['c', 3]]);
for(var [key, val] of map){
log(key); // => 'a', 'b', 'c'
log(val); // => 1, 2, 3
}
for(var val of map.values())log(val); // => 1, 2, 3
for(var key of map.keys())log(key); // => 'a', 'b', 'c'
for(var [key, val] of map.entries()){
log(key); // => 'a', 'b', 'c'
log(val); // => 1, 2, 3
}
var set = new Set([1, 2, 3, 2, 1]);
for(var val of set)log(val); // => 1, 2, 3
for(var val of set.values())log(val); // => 1, 2, 3
for(var key of set.keys())log(key); // => 1, 2, 3
for(var [key, val] of set.entries()){
log(key); // => 1, 2, 3
log(val); // => 1, 2, 3
}
for(var x of document.querySelectorAll('*')){
log(x.id);
}
```
Modules [`core.is-iterable`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.is-iterable.js), [`core.get-iterator`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.get-iterator.js), [`core.get-iterator-method`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.get-iterator-method.js) - helpers for check iterable / get iterator in `library` version or, for example, for `arguments` object:
```javascript
core
.isIterable(var) -> bool
.getIterator(iterable) -> iterator
.getIteratorMethod(var) -> function | undefined
```
[Example](http://goo.gl/SXsM6D):
```js
var list = (function(){
return arguments;
})(1, 2, 3);
log(core.isIterable(list)); // true;
var iter = core.getIterator(list);
log(iter.next().value); // 1
log(iter.next().value); // 2
log(iter.next().value); // 3
log(iter.next().value); // undefined
core.getIterator({}); // TypeError: [object Object] is not iterable!
var iterFn = core.getIteratorMethod(list);
log(typeof iterFn); // 'function'
var iter = iterFn.call(list);
log(iter.next().value); // 1
log(iter.next().value); // 2
log(iter.next().value); // 3
log(iter.next().value); // undefined
log(core.getIteratorMethod({})); // undefined
```
#### ECMAScript 6: Promise
Module [`es6.promise`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.promise.js).
```javascript
new Promise(executor(resolve(var), reject(var))) -> promise
#then(resolved(var), rejected(var)) -> promise
#catch(rejected(var)) -> promise
.resolve(var || promise) -> promise
.reject(var) -> promise
.all(iterable) -> promise
.race(iterable) -> promise
```
Basic [example](http://goo.gl/vGrtUC):
```javascript
function sleepRandom(time){
return new Promise(function(resolve, reject){
setTimeout(resolve, time * 1e3, 0 | Math.random() * 1e3);
});
}
log('Run'); // => Run
sleepRandom(5).then(function(result){
log(result); // => 869, after 5 sec.
return sleepRandom(10);
}).then(function(result){
log(result); // => 202, after 10 sec.
}).then(function(){
log('immediately after'); // => immediately after
throw Error('Irror!');
}).then(function(){
log('will not be displayed');
}).catch(log); // => => Error: Irror!
```
`Promise.resolve` and `Promise.reject` [example](http://goo.gl/vr8TN3):
```javascript
Promise.resolve(42).then(log); // => 42
Promise.reject(42).catch(log); // => 42
Promise.resolve($.getJSON('/data.json')); // => ES6 promise
```
`Promise.all` [example](http://goo.gl/RdoDBZ):
```javascript
Promise.all([
'foo',
sleepRandom(5),
sleepRandom(15),
sleepRandom(10) // after 15 sec:
]).then(log); // => ['foo', 956, 85, 382]
```
`Promise.race` [example](http://goo.gl/L8ovkJ):
```javascript
function timeLimit(promise, time){
return Promise.race([promise, new Promise(function(resolve, reject){
setTimeout(reject, time * 1e3, Error('Await > ' + time + ' sec'));
})]);
}
timeLimit(sleepRandom(5), 10).then(log); // => 853, after 5 sec.
timeLimit(sleepRandom(15), 10).catch(log); // Error: Await > 10 sec
```
ECMAScript 7 [async functions](https://tc39.github.io/ecmascript-asyncawait) [example](http://goo.gl/wnQS4j):
```javascript
var delay = time => new Promise(resolve => setTimeout(resolve, time))
async function sleepRandom(time){
await delay(time * 1e3);
return 0 | Math.random() * 1e3;
};
async function sleepError(time, msg){
await delay(time * 1e3);
throw Error(msg);
};
(async () => {
try {
log('Run'); // => Run
log(await sleepRandom(5)); // => 936, after 5 sec.
var [a, b, c] = await Promise.all([
sleepRandom(5),
sleepRandom(15),
sleepRandom(10)
]);
log(a, b, c); // => 210 445 71, after 15 sec.
await sleepError(5, 'Irror!');
log('Will not be displayed');
} catch(e){
log(e); // => Error: 'Irror!', after 5 sec.
}
})();
```
`core-js` `Promise` supports (but not adds to native implementations) unhandled rejection tracking. In browser you will see notify in console, in node.js / io.js you can use [`unhandledRejection`](https://gist.github.com/benjamingr/0237932cee84712951a2) event.
#### ECMAScript 6: Reflect
Modules [`es6.reflect.apply`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.apply.js), [`es6.reflect.construct`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.construct.js), [`es6.reflect.define-property`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.define-property.js), [`es6.reflect.delete-property`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.delete-property.js), [`es6.reflect.enumerate`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.enumerate.js), [`es6.reflect.get`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.get.js), [`es6.reflect.get-own-property-descriptor`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.get-own-property-descriptor.js), [`es6.reflect.get-prototype-of`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.get-prototype-of.js), [`es6.reflect.has`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.has.js), [`es6.reflect.is-extensible`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.is-extensible.js), [`es6.reflect.own-keys`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.own-keys.js), [`es6.reflect.prevent-extensions`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.prevent-extensions.js), [`es6.reflect.set`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.set.js), [`es6.reflect.set-prototype-of`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es6.reflect.set-prototype-of.js).
```javascript
Reflect
.apply(target, thisArgument, argumentsList) -> var
.construct(target, argumentsList, newTarget?) -> object
.defineProperty(target, propertyKey, attributes) -> bool
.deleteProperty(target, propertyKey) -> bool
.enumerate(target) -> iterator
.get(target, propertyKey, receiver?) -> var
.getOwnPropertyDescriptor(target, propertyKey) -> desc
.getPrototypeOf(target) -> object | null
.has(target, propertyKey) -> bool
.isExtensible(target) -> bool
.ownKeys(target) -> array
.preventExtensions(target) -> bool
.set(target, propertyKey, V, receiver?) -> bool
.setPrototypeOf(target, proto) -> bool (required __proto__ - IE11+)
```
[Example](http://goo.gl/gVT0cH):
```javascript
var O = {a: 1};
Object.defineProperty(O, 'b', {value: 2});
O[Symbol('c')] = 3;
Reflect.ownKeys(O); // => ['a', 'b', Symbol(c)]
function C(a, b){
this.c = a + b;
}
var instance = Reflect.construct(C, [20, 22]);
instance.c; // => 42
```
### ECMAScript 7
* `Array#includes` [proposal](https://github.com/domenic/Array.prototype.includes) - module [`es7.array.includes`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.array.includes.js)
* `String#at` [proposal](https://github.com/mathiasbynens/String.prototype.at) - module [`es7.string.at`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.string.at.js)
* `String#padLeft`, `String#padRight` [proposal](https://github.com/ljharb/proposal-string-pad-left-right) - modules [`es7.string.pad-left`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.string.pad-left.js), [`es7.string.pad-right`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.string.pad-right.js)
* `String#trimLeft`, `String#trimRight` [proposal](https://github.com/sebmarkbage/ecmascript-string-left-right-trim) - modules [`es7.string.trim-left`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.string.trim-right.js), [`es7.string.trim-right`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.string.trim-right.js)
* `Object.values`, `Object.entries` [tc39 discuss](https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-04/apr-9.md#51-objectentries-objectvalues) - modules [`es7.object.values`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.object.values.js), [`es7.object.entries`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.object.entries.js)
* `Object.getOwnPropertyDescriptors` [proposal](https://gist.github.com/WebReflection/9353781) - module [`es7.object.get-own-property-descriptors`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.object.get-own-property-descriptors.js)
* `RegExp.escape` [proposal](https://github.com/benjamingr/RexExp.escape) - module [`es7.regexp.escape`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.regexp.escape.js)
* `Map#toJSON`, `Set#toJSON` [proposal](https://github.com/DavidBruant/Map-Set.prototype.toJSON) - modules [`es7.map.to-json`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.map.to-json.js), [`es7.set.to-json`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/es7.set.to-json.js)
```javascript
Array
#includes(var, from?) -> bool
String
#at(index) -> string
#padLeft(length, fillStr = ' ') -> string
#padRight(length, fillStr = ' ') -> string
#trimLeft() -> string
#trimRight() -> string
Object
.values(object) -> array
.entries(object) -> array
.getOwnPropertyDescriptors(object) -> object
RegExp
.escape(str) -> str
Map
#toJSON() -> array
Set
#toJSON() -> array
```
[Examples](http://goo.gl/aUZQRH):
```javascript
[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
'a𠮷b'.at(1); // => '𠮷'
'a𠮷b'.at(1).length; // => 2
'hello'.padLeft(10); // => ' hello'
'hello'.padLeft(10, '1234'); // => '41234hello'
'hello'.padRight(10); // => 'hello '
'hello'.padRight(10, '1234'); // => 'hello12341'
' hello '.trimLeft(); // => 'hello '
' hello '.trimRight(); // => ' hello'
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]]
// Shallow object cloning with prototype and descriptors:
var copy = Object.create(Object.getPrototypeOf(O), Object.getOwnPropertyDescriptors(O));
// Mixin:
Object.defineProperties(target, Object.getOwnPropertyDescriptors(source));
RegExp.escape('Hello, []{}()*+?.\\^$|!'); // => 'Hello, \[\]\{\}\(\)\*\+\?\.\\\^\$\|!'
JSON.stringify(new Map([['a', 'b'], ['c', 'd']])); // => '[["a","b"],["c","d"]]'
JSON.stringify(new Set([1, 2, 3, 2, 1])); // => '[1,2,3]'
```
### Mozilla JavaScript: Array generics
Module [`js.array.statics`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/js.array.statics.js).
```javascript
Array
.{...ArrayPrototype methods}
```
```javascript
Array.slice(arguments, 1);
Array.join('abcdef', '+'); // => 'a+b+c+d+e+f'
var form = document.getElementsByClassName('form__input');
Array.reduce(form, function(memo, it){
memo[it.name] = it.value;
return memo;
}, {}); // => {name: 'Vasya', age: '42', sex: 'yes, please'}
```
### setTimeout / setInterval
Module [`web.timers`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/web.timers.js). Additional arguments fix for IE9-.
```javascript
setTimeout(fn(...args), time, ...args) -> id
setInterval(fn(...args), time, ...args) -> id
```
```javascript
// Before:
setTimeout(log.bind(null, 42), 1000);
// After:
setTimeout(log, 1000, 42);
```
### setImmediate
Module [`web.immediate`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/web.immediate.js). [setImmediate](https://developer.mozilla.org/en-US/docs/Web/API/Window.setImmediate) polyfill.
```javascript
setImmediate(fn(...args), ...args) -> id
clearImmediate(id) -> void
```
[Example](http://goo.gl/6nXGrx):
```javascript
setImmediate(function(arg1, arg2){
log(arg1, arg2); // => Message will be displayed with minimum delay
}, 'Message will be displayed', 'with minimum delay');
clearImmediate(setImmediate(function(){
log('Message will not be displayed');
}));
```
### Console
Module [`core.log`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.log.js). Console cap for old browsers and some additional functionality. In IE, Node.js / IO.js and Firebug `console` methods not require call from `console` object, but in Chromium and V8 this throws error. For some reason, we can't replace `console` methods by their bound versions. Add `log` object with bound console methods. Some more sugar: `log` is shortcut for `log.log`, we can disable output.
```javascript
log ==== log.log
.{...console API}
.enable() -> void
.disable() -> void
```
```javascript
// Before:
if(window.console && console.warn)console.warn(42);
// After:
log.warn(42);
// Before:
setTimeout(console.warn.bind(console, 42), 1000);
[1, 2, 3].forEach(console.warn, console);
// After:
setTimeout(log.warn, 1000, 42);
[1, 2, 3].forEach(log.warn);
// log is shortcut for log.log
setImmediate(log, 42); // => 42
log.disable();
log.warn('Console is disabled, you will not see this message.');
log.enable();
log.warn('Console is enabled again.');
```
### Object
Modules [`core.object.is-object`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.object.is-object.js), [`core.object.classof`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.object.classof.js), [`core.object.define`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.object.define.js), [`core.object.make`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.object.make.js).
```javascript
Object
.isObject(var) -> bool
.classof(var) -> string
.define(target, mixin) -> target
.make(proto | null, mixin?) -> object
```
Object classify [examples](http://goo.gl/YZQmGo):
```javascript
Object.isObject({}); // => true
Object.isObject(isNaN); // => true
Object.isObject(null); // => false
var classof = Object.classof;
classof(null); // => 'Null'
classof(undefined); // => 'Undefined'
classof(1); // => 'Number'
classof(true); // => 'Boolean'
classof('string'); // => 'String'
classof(Symbol()); // => 'Symbol'
classof(new Number(1)); // => 'Number'
classof(new Boolean(true)); // => 'Boolean'
classof(new String('string')); // => 'String'
var fn = function(){}
, list = (function(){return arguments})(1, 2, 3);
classof({}); // => 'Object'
classof(fn); // => 'Function'
classof([]); // => 'Array'
classof(list); // => 'Arguments'
classof(/./); // => 'RegExp'
classof(new TypeError); // => 'Error'
classof(new Set); // => 'Set'
classof(new Map); // => 'Map'
classof(new WeakSet); // => 'WeakSet'
classof(new WeakMap); // => 'WeakMap'
classof(new Promise(fn)); // => 'Promise'
classof([].values()); // => 'Array Iterator'
classof(new Set().values()); // => 'Set Iterator'
classof(new Map().values()); // => 'Map Iterator'
classof(Math); // => 'Math'
classof(JSON); // => 'JSON'
function Example(){}
Example.prototype[Symbol.toStringTag] = 'Example';
classof(new Example); // => 'Example'
```
`Object.define` and `Object.make` [examples](http://goo.gl/rtpD5Z):
```javascript
// Before:
Object.defineProperty(target, 'c', {
enumerable: true,
configurable: true,
get: function(){
return this.a + this.b;
}
});
// After:
Object.define(target, {
get c(){
return this.a + this.b;
}
});
// Shallow object cloning with prototype and descriptors:
var copy = Object.make(Object.getPrototypeOf(src), src);
// Simple inheritance:
function Vector2D(x, y){
this.x = x;
this.y = y;
}
Object.define(Vector2D.prototype, {
get xy(){
return Math.hypot(this.x, this.y);
}
});
function Vector3D(x, y, z){
Vector2D.apply(this, arguments);
this.z = z;
}
Vector3D.prototype = Object.make(Vector2D.prototype, {
constructor: Vector3D,
get xyz(){
return Math.hypot(this.x, this.y, this.z);
}
});
var vector = new Vector3D(9, 12, 20);
log(vector.xy); // => 15
log(vector.xyz); // => 25
vector.y++;
log(vector.xy); // => 15.811388300841896
log(vector.xyz); // => 25.495097567963924
```
### Dict
Module [`core.dict`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.dict.js). Based on [TC39 discuss](https://github.com/rwaldron/tc39-notes/blob/master/es6/2012-11/nov-29.md#collection-apis-review) / [strawman](http://wiki.ecmascript.org/doku.php?id=harmony:modules_standard#dictionaries).
```javascript
[new] Dict(iterable (entries) | object ?) -> dict
.isDict(var) -> bool
.values(object) -> iterator
.keys(object) -> iterator
.entries(object) -> iterator (entries)
.has(object, key) -> bool
.get(object, key) -> val
.set(object, key, value) -> object
.forEach(object, fn(val, key, @), that) -> void
.map(object, fn(val, key, @), that) -> new @
.mapPairs(object, fn(val, key, @), that) -> new @
.filter(object, fn(val, key, @), that) -> new @
.some(object, fn(val, key, @), that) -> bool
.every(object, fn(val, key, @), that) -> bool
.find(object, fn(val, key, @), that) -> val
.findKey(object, fn(val, key, @), that) -> key
.keyOf(object, var) -> key
.includes(object, var) -> bool
.reduce(object, fn(memo, val, key, @), memo?) -> var
```
`Dict` create object without prototype from iterable or simple object. [Example](http://goo.gl/pnp8Vr):
```javascript
var map = new Map([['a', 1], ['b', 2], ['c', 3]]);
Dict(); // => {__proto__: null}
Dict({a: 1, b: 2, c: 3}); // => {__proto__: null, a: 1, b: 2, c: 3}
Dict(map); // => {__proto__: null, a: 1, b: 2, c: 3}
Dict([1, 2, 3].entries()); // => {__proto__: null, 0: 1, 1: 2, 2: 3}
var dict = Dict({a: 42});
dict instanceof Object; // => false
dict.a; // => 42
dict.toString; // => undefined
'a' in dict; // => true
'hasOwnProperty' in dict; // => false
Dict.isDict({}); // => false
Dict.isDict(Dict()); // => true
```
`Dict.keys`, `Dict.values` and `Dict.entries` returns iterators for objects, [examples](http://goo.gl/4u8UDK):
```javascript
var dict = {a: 1, b: 2, c: 3};
for(var key of Dict.keys(dict))log(key); // => 'a', 'b', 'c'
for(var val of Dict.values(dict))log(val); // => 1, 2, 3
for(var [key, val] of Dict.entries(dict)){
log(key); // => 'a', 'b', 'c'
log(val); // => 1, 2, 3
}
new Map(Dict.entries(dict)); // => Map {a: 1, b: 2, c: 3}
new Map((for([k, v] of Dict.entries(dict))if(v % 2)[k + k, v * v])); // => Map {aa: 1, cc: 9}
```
Basic dict operations for objects with prototype [example](http://goo.gl/B28UnG):
```js
'q' in {q: 1}; // => true
'toString' in {}; // => true
Dict.has({q: 1}, 'q'); // => true
Dict.has({}, 'toString'); // => false
({q: 1})['q']; // => 1
({}).toString; // => function toString(){ [native code] }
Dict.get({q: 1}, 'q'); // => 1
Dict.get({}, 'toString'); // => undefined
var O = {};
O['q'] = 1;
O['q']; // => 1
O['__proto__'] = {w: 2};
O['__proto__']; // => {w: 2}
O['w']; // => 2
var O = {};
Dict.set(O, 'q', 1);
O['q']; // => 1
Dict.set(O, '__proto__', {w: 2});
O['__proto__']; // => {w: 2}
O['w']; // => undefined
```
Other methods of `Dict` module are static equialents of `Array.prototype` methods for dictionaries, [examples](http://goo.gl/xFi1RH):
```javascript
var dict = {a: 1, b: 2, c: 3};
Dict.forEach(dict, console.log, console);
// => 1, 'a', {a: 1, b: 2, c: 3}
// => 2, 'b', {a: 1, b: 2, c: 3}
// => 3, 'c', {a: 1, b: 2, c: 3}
Dict.map(dict, function(it){
return it * it;
}); // => {a: 1, b: 4, c: 9}
Dict.mapPairs(dict, function(val, key){
if(key != 'b')return [key + key, val * val];
}); // => {aa: 1, cc: 9}
Dict.filter(dict, function(it){
return it % 2;
}); // => {a: 1, c: 3}
Dict.some(dict, function(it){
return it === 2;
}); // => true
Dict.every(dict, function(it){
return it === 2;
}); // => false
Dict.find(dict, function(it){
return it > 2;
}); // => 3
Dict.find(dict, function(it){
return it > 4;
}); // => undefined
Dict.findKey(dict, function(it){
return it > 2;
}); // => 'c'
Dict.findKey(dict, function(it){
return it > 4;
}); // => undefined
Dict.keyOf(dict, 2); // => 'b'
Dict.keyOf(dict, 4); // => undefined
Dict.includes(dict, 2); // => true
Dict.includes(dict, 4); // => false
Dict.reduce(dict, function(memo, it){
return memo + it;
}); // => 6
Dict.reduce(dict, function(memo, it){
return memo + it;
}, ''); // => '123'
```
### Partial application
Module [`core.function.part`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.function.part.js).
```javascript
Function
#part(...args | _) -> fn(...args)
```
`Function#part` partial apply function without `this` binding. Uses global variable `_` (`core._` for builds without global namespace pollution) as placeholder and not conflict with `Underscore` / `LoDash`. [Examples](http://goo.gl/p9ZJ8K):
```javascript
var fn1 = log.part(1, 2);
fn1(3, 4); // => 1, 2, 3, 4
var fn2 = log.part(_, 2, _, 4);
fn2(1, 3); // => 1, 2, 3, 4
var fn3 = log.part(1, _, _, 4);
fn3(2, 3); // => 1, 2, 3, 4
fn2(1, 3, 5); // => 1, 2, 3, 4, 5
fn2(1); // => 1, 2, undefined, 4
```
### Number Iterator
Modules [`core.number.iterator`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.number.iterator.js).
```javascript
Number
#@@iterator() -> iterator
```
[Examples](http://goo.gl/RI60Ot):
```javascript
for(var i of 3)log(i); // => 0, 1, 2
Array.from(10, Math.random); // => [0.9817775336559862, 0.02720663254149258, ...]
Array.from(10); // => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array.from(10, function(it){
return this + it * it;
}, .42); // => [0.42, 1.42, 4.42, 9.42, 16.42, 25.42, 36.42, 49.42, 64.42, 81.42]
// Comprehensions:
[for(i of 10)if(i % 2)i * i]; // => [1, 9, 25, 49, 81]
Dict((for(i of 3)['key' + i, !(i % 2)])); // => {key0: true, key1: false, key2: true}
```
### Escaping HTML
Modules [`core.string.escape-html`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.string.escape-html.js) and [`core.string.unescape-html`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.string.unescape-html.js).
```javascript
String
#escapeHTML() -> str
#unescapeHTML() -> str
```
[Examples](http://goo.gl/6bOvsQ):
```javascript
''.escapeHTML(); // => '<script>doSomething();</script>'
'<script>doSomething();</script>'.unescapeHTML(); // => ''
```
### delay
Module [`core.delay`](https://github.com/zloirock/core-js/blob/v1.1.3/modules/core.delay.js). [Promise](#ecmascript-6-promise)-returning delay function, [esdiscuss](https://esdiscuss.org/topic/promise-returning-delay-function). [Example](http://goo.gl/lbucba):
```javascript
delay(1e3).then(() => log('after 1 sec'));
(async () => {
await delay(3e3);
log('after 3 sec');
while(await delay(3e3))log('each 3 sec');
})();
```
## Missing polyfills
- ES5 `JSON` is missing now only in IE7- and never it will be added to `core-js`, if you need it in these old browsers available many implementations, for example, [json3](https://github.com/bestiejs/json3).
- ES6 Typed Arrays can be polyfilled without serious problems, but it will be slow - getter / setter for each element and they are missing completely only in IE9-. You can use [this polyfill](https://github.com/inexorabletash/polyfill/blob/master/typedarray.js). *Possible*, it will be added to `core-js` in the future, completely or only missing methods of existing arrays.
- ES6 `String#normalize` is not very usefull feature, but this polyfill will be very large. If you need it, you can use [unorm](https://github.com/walling/unorm/).
- ES6 `Proxy` can't be polyfilled, but for Node.js / Chromium with additional flags you can try [harmony-reflect](https://github.com/tvcutsem/harmony-reflect) for adapt old style `Proxy` API to final ES6 version.
- ES7 `Object.observe` can be polyfilled with many limitations, but it will be very slow - dirty checking on each tick. In nearest future it will not be added to `core-js` - it will cause serious slowdown in applications which uses `Object.observe` and fallback if it's missing. *Possible* it will be added as optional feature then most actual browsers will have this feature. Now you can use [this polyfill](https://github.com/MaxArt2501/object-observe).
- ES7 `SIMD`. `core-js` doesn't adds polyfill of this feature because of large size and some other reasons. You can use [this polyfill](https://github.com/tc39/ecmascript_simd/blob/master/src/ecmascript_simd.js).
- `window.fetch` is not crossplatform feature, in some environments it make no sense. For this reason I don't think it should be in `core-js`. Looking at the large number of requests it *maybe* added in the future. Now you can use, for example, [this polyfill](https://github.com/github/fetch).
## Changelog
##### 1.1.4 - 2015.09.05
* fixed support symbols in FF34-35 [`Object.assign`](#ecmascript-6-object)
* fixed [collections iterators](#ecmascript-6-iterators) in FF25-26
* fixed non-generic WebKit [`Array.of`](#ecmascript-6-array)
* some other fixes and optimizations
##### 1.1.3 - 2015.08.29
* fixed support Node.js domains in [`Promise`](#ecmascript-6-promise), [#103](https://github.com/zloirock/core-js/issues/103)
##### 1.1.2 - 2015.08.28
* added `toJSON` method to [`Symbol`](#ecmascript-6-symbol) polyfill and to MS Edge implementation for expected `JSON.stringify` result w/o patching this method
* replaced [`Reflect.construct`](#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)
##### 1.1.1 - 2015.08.20
* added more correct microtask implementation for [`Promise`](#ecmascript-6-promise)
##### 1.1.0 - 2015.08.17
* updated [string padding](#ecmascript-7) to [actual proposal](https://github.com/ljharb/proposal-string-pad-left-right) - renamed, minor internal changes:
* `String#lpad` -> `String#padLeft`
* `String#rpad` -> `String#padRight`
* added [string trim functions](#ecmascript-7) - [proposal](https://github.com/sebmarkbage/ecmascript-string-left-right-trim), defacto standard - required only for IE11- and fixed for some old engines:
* `String#trimLeft`
* `String#trimRight`
* [`String#trim`](#ecmascript-6-string) fixed for some engines by es6 spec and moved from `es5` to single `es6` module
* splitted [`es6.object.statics-accept-primitives`](#ecmascript-6-object)
* caps for `freeze`-family `Object` methods moved from `es5` to `es6` namespace and joined with [es6 wrappers](#ecmascript-6-object)
* `es5` [namespace](#commonjs) also includes modules, moved to `es6` namespace - you can use it as before
* increased `MessageChannel` priority in `$.task`, [#95](https://github.com/zloirock/core-js/issues/95)
* does not get `global.Symbol` on each getting iterator, if you wanna use alternative `Symbol` shim - add it before `core-js`
* [`Reflect.construct`](#ecmascript-6-reflect) optimized and fixed for some cases
* simplified [`Reflect.enumerate`](#ecmascript-6-reflect), see [this question](https://esdiscuss.org/topic/question-about-enumerate-and-property-decision-timing)
* some corrections in [`Math.acosh`](#ecmascript-6-math)
* fixed [`Math.imul`](#ecmascript-6-math) for old WebKit
* some fixes in string / RegExp [well-known symbols](#ecmascript-6-regexp) logic
* some other fixes and optimizations
##### 1.0.1 - 2015.07.31
* 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)
##### 1.0.0 - 2015.07.22
* added logic for [well-known symbols](#ecmascript-6-regexp):
* `Symbol.match`
* `Symbol.replace`
* `Symbol.split`
* `Symbol.search`
* actualized and optimized work with iterables:
* optimized [`Map`, `Set`, `WeakMap`, `WeakSet` constructors](#ecmascript-6-collections), [`Promise.all`, `Promise.race`](#ecmascript-6-promise) for default `Array Iterator`
* optimized [`Array.from`](#ecmascript-6-array) for default `Array Iterator`
* added [`core.getIteratorMethod`](#ecmascript-6-iterators) helper
* uses enumerable properties in shimmed instances - collections, iterators, etc for optimize performance
* added support native constructors to [`Reflect.construct`](#ecmascript-6-reflect) with 2 arguments
* added support native constructors to [`Function#bind`](#ecmascript-5) shim with `new`
* removed obsolete `.clear` methods native [`Weak`-collections](#ecmascript-6-collections)
* maximum modularity, reduced minimal custom build size, separated into submodules:
* [`es6.reflect`](#ecmascript-6-reflect)
* [`es6.regexp`](#ecmascript-6-regexp)
* [`es6.math`](#ecmascript-6-math)
* [`es6.number`](#ecmascript-6-number)
* [`es7.object.to-array`](#ecmascript-7)
* [`core.object`](#object)
* [`core.string`](#escaping-html)
* [`core.iter-helpers`](#ecmascript-6-iterators)
* internal modules (`$`, `$.iter`, etc)
* many other optimizations
* final cleaning non-standard features
* moved `$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`](#number-iterator), `Array.from(2.5)` will be `[0, 1, 2]` instead of `[0, 1]`
* fixed [#85](https://github.com/zloirock/core-js/issues/85) - invalid `Promise` unhandled rejection message in nested `setTimeout`
* fixed [#86](https://github.com/zloirock/core-js/issues/86) - support FF extensions
* fixed [#89](https://github.com/zloirock/core-js/issues/89) - behavior `Number` constructor in strange case
##### 0.9.18 - 2015.06.17
* removed `/` from [`RegExp.escape`](#ecmascript-7) escaped characters
##### 0.9.17 - 2015.06.14
* updated [`RegExp.escape`](#ecmascript-7) to the [latest proposal](https://github.com/benjamingr/RexExp.escape)
* fixed conflict with webpack dev server + IE buggy behavior
##### 0.9.16 - 2015.06.11
* more correct order resolving thenable in [`Promise`](#ecmascript-6-promise) polyfill
* uses polyfill instead of [buggy V8 `Promise`](https://github.com/zloirock/core-js/issues/78)
##### 0.9.15 - 2015.06.09
* [collections](#ecmascript-6-collections) from `library` version return wrapped native instances
* fixed collections prototype methods in `library` version
* optimized [`Math.hypot`](#ecmascript-6-math)
##### 0.9.14 - 2015.06.04
* updated [`Promise.resolve` behavior](https://esdiscuss.org/topic/fixing-promise-resolve)
* added fallback for IE11 buggy `Object.getOwnPropertyNames` + iframe
* some other fixes
##### 0.9.13 - 2015.05.25
* added fallback for [`Symbol` polyfill](#ecmascript-6-symbol) for old Android
* some other fixes
##### 0.9.12 - 2015.05.24
* different instances `core-js` should use / recognize the same symbols
* some fixes
##### 0.9.11 - 2015.05.18
* simplified [custom build](#custom-build)
* add custom build js api
* added `grunt-cli` to `devDependencies` for `npm run grunt`
* some fixes
##### 0.9.10 - 2015.05.16
* 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
##### 0.9.9 - 2015.05.14
* wrapped `Object#propertyIsEnumerable` for [`Symbol` polyfill](#ecmascript-6-symbol)
* [added proto versions of methods to `library` for ES7 bind syntax](https://github.com/zloirock/core-js/issues/65)
* some other fixes
##### 0.9.8 - 2015.05.12
* fixed [`Math.hypot`](#ecmascript-6-math) with negative arguments
* added `Object#toString.toString` as fallback for [`lodash` `isNative`](https://github.com/lodash/lodash/issues/1197)
##### 0.9.7 - 2015.05.07
* 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`
##### 0.9.6 - 2015.05.01
* added [`String#lpad`, `String#rpad`](#ecmascript-7)
##### 0.9.5 - 2015.04.30
* added cap for `Function#@@hasInstance`
* some fixes and optimizations
##### 0.9.4 - 2015.04.27
* fixed `RegExp` constructor
##### 0.9.3 - 2015.04.26
* some fixes and optimizations
##### 0.9.2 - 2015.04.25
* more correct [`Promise`](#ecmascript-6-promise) unhandled rejection tracking and resolving / rejection priority
##### 0.9.1 - 2015.04.25
* fixed `__proto__`-based [`Promise`](#ecmascript-6-promise) subclassing in some environments
##### 0.9.0 - 2015.04.24
* added correct [symbols](#ecmascript-6-symbol) descriptors
* fixed behavior `Object.{assign, create, defineProperty, defineProperties, getOwnPropertyDescriptor, getOwnPropertyDescriptors}` with symbols
* added [single entry points](#commonjs) for `Object.{create, defineProperty, defineProperties}`
* added [`Map#toJSON`](#ecmascript-7)
* 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)
* removed non-standard undocumented methods `Symbol.{pure, set}`
* some fixes and internal changes
##### 0.8.4 - 2015.04.18
* uses `webpack` instead of `browserify` for browser builds - more compression-friendly result
##### 0.8.3 - 2015.04.14
* fixed `Array` statics with single entry points
##### 0.8.2 - 2015.04.13
* [`Math.fround`](#ecmascript-6-math) now also works in IE9-
* added [`Set#toJSON`](#ecmascript-7)
* some optimizations and fixes
##### 0.8.1 - 2015.04.03
* fixed `Symbol.keyFor`
##### 0.8.0 - 2015.04.02
* changed [CommonJS API](#commonjs)
* splitted and renamed some modules
* 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](#commonjs)
* removed [abstract references](https://github.com/zenparsing/es-abstract-refs) support - proposal has been superseded =\
* [`$for.isIterable` -> `core.isIterable`, `$for.getIterator` -> `core.getIterator`](#ecmascript-6-iterators), temporary available in old namespace
* fixed iterators support in v8 `Promise.all` and `Promise.race`
* many other fixes
##### 0.7.2 - 2015.03.09
* some fixes
##### 0.7.1 - 2015.03.07
* some fixes
##### 0.7.0 - 2015.03.06
* rewritten and splitted into [CommonJS modules](#commonjs)
##### 0.6.1 - 2015.02.24
* fixed support [`Object.defineProperty`](#ecmascript-5) with accessors on DOM elements on IE8
##### 0.6.0 - 2015.02.23
* added support safe closing iteration - calling `iterator.return` on abort iteration, if it exists
* added basic support [`Promise`](#ecmascript-6-promise) unhandled rejection tracking in shim
* added [`Object.getOwnPropertyDescriptors`](#ecmascript-7)
* removed `console` cap - creates too many problems - you can use [`core.log`](#console) module as that
* restructuring [namespaces](#custom-build)
* some fixes
##### 0.5.4 - 2015.02.15
* some fixes
##### 0.5.3 - 2015.02.14
* added [support binary and octal literals](#ecmascript-6-number) to `Number` constructor
* added [`Date#toISOString`](#ecmascript-5)
##### 0.5.2 - 2015.02.10
* some fixes
##### 0.5.1 - 2015.02.09
* some fixes
##### 0.5.0 - 2015.02.08
* systematization of modules
* splitted [`es6` module](#ecmascript-6)
* splitted [`console` module](#console): `web.console` - only cap for missing methods, `core.log` - bound methods & additional features
* added [`delay` method](#delay)
* some fixes
##### 0.4.10 - 2015.01.28
* [`Object.getOwnPropertySymbols`](#ecmascript-6-symbol) polyfill returns array of wrapped keys
##### 0.4.9 - 2015.01.27
* FF20-24 fix
##### 0.4.8 - 2015.01.25
* some [collections](#ecmascript-6-collections) fixes
##### 0.4.7 - 2015.01.25
* added support frozen objects as [collections](#ecmascript-6-collections) keys
##### 0.4.6 - 2015.01.21
* added [`Object.getOwnPropertySymbols`](#ecmascript-6-symbol)
* added [`NodeList.prototype[@@iterator]`](#ecmascript-6-iterators)
* added basic `@@species` logic - getter in native constructors
* removed `Function#by`
* some fixes
##### 0.4.5 - 2015.01.16
* some fixes
##### 0.4.4 - 2015.01.11
* enabled CSP support
##### 0.4.3 - 2015.01.10
* added `Function` instances `name` property for IE9+
##### 0.4.2 - 2015.01.10
* `Object` static methods accept primitives
* `RegExp` constructor can alter flags (IE9+)
* added `Array.prototype[Symbol.unscopables]`
##### 0.4.1 - 2015.01.05
* some fixes
##### 0.4.0 - 2015.01.03
* added [`es6.reflect`](#ecmascript-6-reflect) module:
* added `Reflect.apply`
* added `Reflect.construct`
* added `Reflect.defineProperty`
* added `Reflect.deleteProperty`
* added `Reflect.enumerate`
* added `Reflect.get`
* added `Reflect.getOwnPropertyDescriptor`
* added `Reflect.getPrototypeOf`
* added `Reflect.has`
* added `Reflect.isExtensible`
* added `Reflect.preventExtensions`
* added `Reflect.set`
* added `Reflect.setPrototypeOf`
* `core-js` methods now can use external `Symbol.iterator` polyfill
* some fixes
##### 0.3.3 - 2014.12.28
* [console cap](#console) excluded from node.js default builds
##### 0.3.2 - 2014.12.25
* added cap for [ES5](#ecmascript-5) freeze-family methods
* fixed `console` bug
##### 0.3.1 - 2014.12.23
* some fixes
##### 0.3.0 - 2014.12.23
* Optimize [`Map` & `Set`](#ecmascript-6-collections):
* use entries chain on hash table
* fast & correct iteration
* iterators moved to [`es6`](#ecmascript-6) and [`es6.collections`](#ecmascript-6-collections) modules
##### 0.2.5 - 2014.12.20
* `console` no longer shortcut for `console.log` (compatibility problems)
* some fixes
##### 0.2.4 - 2014.12.17
* better compliance of ES6
* added [`Math.fround`](#ecmascript-6-math) (IE10+)
* some fixes
##### 0.2.3 - 2014.12.15
* [Symbols](#ecmascript-6-symbol):
* added option to disable addition setter to `Object.prototype` for Symbol polyfill:
* added `Symbol.useSimple`
* added `Symbol.useSetter`
* added cap for well-known Symbols:
* added `Symbol.hasInstance`
* added `Symbol.isConcatSpreadable`
* added `Symbol.match`
* added `Symbol.replace`
* added `Symbol.search`
* added `Symbol.species`
* added `Symbol.split`
* added `Symbol.toPrimitive`
* added `Symbol.unscopables`
##### 0.2.2 - 2014.12.13
* added [`RegExp#flags`](#ecmascript-6-regexp) ([December 2014 Draft Rev 29](http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#december_6_2014_draft_rev_29))
* added [`String.raw`](#ecmascript-6-string)
##### 0.2.1 - 2014.12.12
* repair converting -0 to +0 in [native collections](#ecmascript-6-collections)
##### 0.2.0 - 2014.12.06
* added [`es7.proposals`](#ecmascript-7) and [`es7.abstract-refs`](https://github.com/zenparsing/es-abstract-refs) modules
* added [`String#at`](#ecmascript-7)
* added real [`String Iterator`](#ecmascript-6-iterators), older versions used Array Iterator
* added abstract references support:
* added `Symbol.referenceGet`
* added `Symbol.referenceSet`
* added `Symbol.referenceDelete`
* added `Function#@@referenceGet`
* added `Map#@@referenceGet`
* added `Map#@@referenceSet`
* added `Map#@@referenceDelete`
* added `WeakMap#@@referenceGet`
* added `WeakMap#@@referenceSet`
* added `WeakMap#@@referenceDelete`
* added `Dict.{...methods}[@@referenceGet]`
* removed deprecated `.contains` methods
* some fixes
##### 0.1.5 - 2014.12.01
* added [`Array#copyWithin`](#ecmascript-6-array)
* added [`String#codePointAt`](#ecmascript-6-string)
* added [`String.fromCodePoint`](#ecmascript-6-string)
##### 0.1.4 - 2014.11.27
* added [`Dict.mapPairs`](#dict)
##### 0.1.3 - 2014.11.20
* [TC39 November meeting](https://github.com/rwaldron/tc39-notes/tree/master/es6/2014-11):
* [`.contains` -> `.includes`](https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-11/nov-18.md#51--44-arrayprototypecontains-and-stringprototypecontains)
* `String#contains` -> [`String#includes`](#ecmascript-6-string)
* `Array#contains` -> [`Array#includes`](#ecmascript-7)
* `Dict.contains` -> [`Dict.includes`](#dict)
* [removed `WeakMap#clear`](https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-11/nov-19.md#412-should-weakmapweakset-have-a-clear-method-markm)
* [removed `WeakSet#clear`](https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-11/nov-19.md#412-should-weakmapweakset-have-a-clear-method-markm)
##### 0.1.2 - 2014.11.19
* `Map` & `Set` bug fix
##### 0.1.1 - 2014.11.18
* public release