core-js

Core.js

Alternative modular compact (max. ~23kb w/o gzip) standard library for JavaScript. Includes polyfills for ECMAScript 5, ECMAScript 6: symbols, collections, iterators, promises; setImmediate, array generics, console cap. Some additional functionality such as dictionaries, extended partial application, date formatting.

Example:

console.log(Array.from(new Set([1, 2, 3, 2, 1]))); // => [1, 2, 3]
console.log('*'.repeat(10));                       // => '**********'
Promise.resolve(32).then(console.log);             // => 32
setImmediate(console.log, 42);                     // => 42

Without extension of native objects:

var log  = core.console.log;
log(core.Array.from(new core.Set([1, 2, 3, 2, 1]))); // => [1, 2, 3]
log(core.String.repeat('*', 10));                    // => '**********'
core.Promise.resolve(32).then(log);                  // => 32
core.setImmediate(log, 42);                          // => 42

• API
  • ECMAScript 5
  • ECMAScript 6
  • ECMAScript 6: Symbols
  • ECMAScript 6: Collections
  • ECMAScript 6: Iterators
  • ECMAScript 6: Promises
  • ECMAScript 6: Reflect
  • ECMAScript 7
  • ECMAScript 7: Abstract References
  • Mozilla JavaScript: Array generics
  • setTimeout / setInterval
  • setImmediate
  • console
  • Object
  • Dict
  • Partial application
  • Date formatting
  • Array
  • Number
  • Escaping characters
• Install
• Changelog

API:

ECMAScript 5

Module es5, nothing new - without examples.

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
  .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-
  .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)
String
  #trim() -> str
Date
  .now() -> int

ECMAScript 6

Module es6. About iterators from this module here. Symbols, collections and promises in separate modules.

ECMAScript 6: Object

Object
  .assign(target, ...src) -> target
  .is(a, b) -> bool
  .setPrototypeOf(target, proto | null) -> target, sham(ie11+)
  #toString() -> string, fix for @@toStringTag support
Function
  #name -> string (IE9+)

Example:

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]'

(function foo(){}).name // => 'foo'

ECMAScript 6: Array

Array
  .from(iterable | array-like, mapFn(val, index)?, that) -> array
  .of(...args) -> array
  #copyWithin(target = 0, start = 0, end = @length) -> @
  #fill(var, start = 0, end = @length) -> @
  #find(fn(val, index, @), that) -> var
  #findIndex(fn(val, index, @), that) -> int
  #@@unscopables -> object

Example:

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 & RegExp

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
RegExp
  #flags -> str (getter, IE9+)

Example:

'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!'
String.raw({raw: 'test'}, 0, 1, 2); // => 't0e1s2t'

/foo/.flags;    // => ''
/foo/gim.flags; // => 'gim'

ECMAScript 6: Number & Math

Number
  .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
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 (IE10+)
  .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: Symbols

Module es6_symbol.

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
  .pure(description?) -> symbol || string
  .set(object, key, val) -> object

Basic example:

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');
console.log(person.getName());          // => 'Vasya'
console.log(person['name']);            // => undefined
console.log(person[Symbol('name')]);    // => undefined, symbols are uniq
for(var key in person)console.log(key); // => only 'getName', symbols are not enumerable

Symbol.for & Symbol.keyFor example:

var symbol = Symbol.for('key');
symbol === Symbol.for('key'); // true
Symbol.keyFor(symbol);        // 'key'

By default, Symbol polyfill define setter in Object.prototype. You can disable it. Example:

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

Reflect.ownKeys from Reflect module returns all object keys - strings & symbols.

ECMAScript 6: Collections

Module es6_collections. About iterators from this module here.

Map

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

Example:

var a = [1];

var map = new Map([['a', 1], [42, 2]]);
map.set(a, 3).set(true, 4);

console.log(map.size);        // => 4
console.log(map.has(a));      // => true
console.log(map.has([1]));    // => false
console.log(map.get(a));      // => 3
map.forEach(function(val, key){
  console.log(val);           // => 1, 2, 3, 4
  console.log(key);           // => 'a', 42, [1], true
});
map.delete(a);
console.log(map.size);        // => 3
console.log(map.get(a));      // => undefined
console.log(Array.from(map)); // => [['a', 1], [42, 2], [true, 4]]

Set

new Set(iterable?) -> set
  #add(key) -> @
  #clear() -> void
  #delete(key) -> bool
  #forEach(fn(el, el, @), that) -> void
  #has(key) -> bool
  #size

Example:

var set = new Set(['a', 'b', 'a', 'c']);
set.add('d').add('b').add('e');
console.log(set.size);        // => 5
console.log(set.has('b'));    // => true
set.forEach(function(it){
  console.log(it);            // => 'a', 'b', 'c', 'd', 'e'
});
set.delete('b');
console.log(set.size);        // => 4
console.log(set.has('b'));    // => false
console.log(Array.from(set)); // => ['a', 'c', 'd', 'e']

WeakMap

new WeakMap(iterable (entries) ?) -> weakmap
  #delete(key) -> bool
  #get(key) -> val
  #has(key) -> bool
  #set(key, val) -> @

Example:

var a = [1]
  , b = [2]
  , c = [3];

var wmap = new WeakMap([[a, 1], [b, 2]]);
wmap.set(c, 3).set(b, 4);
console.log(wmap.has(a));   // => true
console.log(wmap.has([1])); // => false
console.log(wmap.get(a));   // => 1
wmap.delete(a);
console.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');
console.log(person.getName());          // => 'Vasya'
for(var key in person)console.log(key); // => only 'getName'

WeakSet

new WeakSet(iterable?) -> weakset
  #add(key) -> @
  #delete(key) -> bool
  #has(key) -> bool

Example:

var a = [1]
  , b = [2]
  , c = [3];

var wset = new WeakSet([a, b, a]);
wset.add(c).add(b).add(c);
console.log(wset.has(b));   // => true
console.log(wset.has([2])); // => false
wset.delete(b);
console.log(wset.has(b));   // => false

ECMAScript 6: Iterators

Module es6:

String
  #@@iterator() -> iterator
Array
  #values() -> iterator
  #keys() -> iterator
  #entries() -> iterator (entries)
  #@@iterator() -> iterator
Arguments
  #@@iterator() -> iterator (sham, available only in core-js methods)

Module es6_collections:

Set
  #values() -> iterator
  #keys() -> iterator
  #entries() -> iterator (entries)
  #@@iterator() -> iterator
Map
  #values() -> iterator
  #keys() -> iterator
  #entries() -> iterator (entries)
  #@@iterator() -> iterator (entries)

Example:

var string = 'a𠮷b';

for(var val of string)console.log(val);         // => 'a', '𠮷', 'b'

var array = ['a', 'b', 'c'];

for(var val of array)console.log(val);          // => 'a', 'b', 'c'
for(var val of array.values())console.log(val); // => 'a', 'b', 'c'
for(var key of array.keys())console.log(key);   // => 0, 1, 2
for(var [key, val] of array.entries()){
  console.log(key);                             // => 0, 1, 2
  console.log(val);                             // => 'a', 'b', 'c'
}

var map = new Map([['a', 1], ['b', 2], ['c', 3]]);

for(var [key, val] of map){
  console.log(key);                             // => 'a', 'b', 'c'
  console.log(val);                             // => 1, 2, 3
}
for(var val of map.values())console.log(val);   // => 1, 2, 3
for(var key of map.keys())console.log(key);     // => 'a', 'b', 'c'
for(var [key, val] of map.entries()){
  console.log(key);                             // => 'a', 'b', 'c'
  console.log(val);                             // => 1, 2, 3
}

var set = new Set([1, 2, 3, 2, 1]);

for(var val of set)console.log(val);            // => 1, 2, 3
for(var val of set.values())console.log(val);   // => 1, 2, 3
for(var key of set.keys())console.log(key);     // => 1, 2, 3
for(var [key, val] of set.entries()){
  console.log(key);                             // => 1, 2, 3
  console.log(val);                             // => 1, 2, 3
}

Module $for - iterators chaining - for-of and array / generator comprehensions helpers for ES5- syntax.

$for(iterable, entries) -> iterator ($for)
  #of(fn(value, key?), that) -> void
  #array(mapFn(value, key?)?, that) -> array
  #filter(fn(value, key?), that) -> iterator ($for)
  #map(fn(value, key?), that) -> iterator ($for)
  .isIterable(var) -> bool
  .getIterator(iterable) -> iterator

Examples:

$for(new Set([1, 2, 3, 2, 1])).of(function(it){
  console.log(it); // => 1, 2, 3
});

$for([1, 2, 3].entries(), true).of(function(key, value){
  console.log(key);   // => 0, 1, 2
  console.log(value); // => 1, 2, 3
});

$for('abc').of(console.log, console); // => 'a', 'b', 'c'

$for([1, 2, 3, 4, 5]).of(function(it){
  console.log(it); // => 1, 2, 3
  if(it == 3)return false;
});

var ar1 = $for([1, 2, 3]).array(function(v){
  return v * v;
}); // => [1, 4, 9]

var set = new Set([1, 2, 3, 2, 1]);
var ar1 = $for(set).filter(function(v){
  return v % 2;
}).array(function(v){
  return v * v;
}); // => [1, 9]

var iter = $for(set).filter(function(v){
  return v % 2;
}).map(function(v){
  return v * v;
});
iter.next(); // => {value: 1, done: false}
iter.next(); // => {value: 9, done: false}
iter.next(); // => {value: undefined, done: true}

var map1 = new Map([['a', 1], ['b', 2], ['c', 3]]);
var map2 = new Map($for(map1, true).filter(function(k, v){
  return v % 2;
}).map(function(k, v){
  return [k + k, v * v];
})); // => Map {aa: 1, cc: 9}

ECMAScript 6: Promises

Module es6_promise.

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:

var log = console.log.bind(console);
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:

Promise.resolve(42).then(log); // => 42
Promise.reject(42).catch(log); // => 42

Promise.resolve($.getJSON('/data.json')); // => ES6 promise

Promise.all example:

Promise.all([
  'foo',
  sleepRandom(5),
  sleepRandom(15),
  sleepRandom(10)  // after 15 sec:
]).then(log);      // => ['foo', 956, 85, 382]

Promise.race example:

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 example:

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.
  }
})();

ECMAScript 6: Reflect

Module es6_reflect.

Reflect
  .apply(target, thisArgument, argumentsList) -> var
  .construct(target, argumentsList) -> 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, sham(ie11+)

Example:

var O = {a: 1};
Object.defineProperty(O, 'b', {value: 2});
O[Symbol('c')] = 3;
console.log(Reflect.ownKeys(O)); // => ['a', 'b', Symbol(c)]

function C(a, b){
  this.c = a + b;
}

var instance = Reflect.construct(C, [20, 22]);
console.log(instance.c); // => 42

ECMAScript 7

Module es7.

• Array#includes proposal
• String#at proposal
• Object.values, Object.entries tc39 discuss
• RegExp.escape proposal

Array
  #includes(var, from?) -> bool
String
  #at(index) -> string
Object
  .values(object) -> array
  .entries(object) -> array
RegExp
  .escape(str) -> str

Examples:

[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

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]]

RegExp.escape('Hello -[]{}()*+?.,\\^$|'); // => 'Hello \-\[\]\{\}\(\)\*\+\?\.\,\\\^\$\|'

ECMAScript 7: Abstract References

Module es7_refs. Symbols and methods for abstract references. At the moment, they are supported only by several translators, such as 6to5.

Symbol
  .referenceGet -> @@referenceGet
  .referenceSet -> @@referenceSet
  .referenceDelete -> @@referenceDelete
Function
  #@@referenceGet() -> @
Map
  #@@referenceGet ==== #get
  #@@referenceSet ==== #set
  #@@referenceDelete ==== #delete
WeakMap
  #@@referenceGet ==== #get
  #@@referenceSet ==== #set
  #@@referenceDelete ==== #delete

Private properties example with WeakMaps, class and basic abstract refs syntax:

var Person = (NAME => class {
  constructor(name){
    this::NAME = name;
  }
  getName(){
    return this::NAME;
  }
})(new WeakMap);

var person = new Person('Vasya');
console.log(person.getName());          // => 'Vasya'
for(var key in person)console.log(key); // => only 'getName'

The same example with the private keyword:

class Person {
  private NAME
  constructor(name){
    this::NAME = name;
  }
  getName(){
    return this::NAME;
  }
}

var person = new Person('Vasya');
console.log(person.getName());          // => 'Vasya'
for(var key in person)console.log(key); // => only 'getName'

Virtual methods example:

var {toString} = {};
console.log([]::toString()); // => '[object Array]'

function sum(){
  var {reduce} = [];
  return arguments::reduce((a, b)=> a + b);
}
console.log(sum(1, 2, 3, 4, 5)); // => 15

Methods from Dict module override @@referenceGet method, example:

var {filter, map} = Dict;
var dict = {q: 1, w: 2, e: 3}::filter((v, k) => k != 'w')::map(v => v * v); // => {"q":1,"e":9}

Mozilla JavaScript: Array generics

Module array_statics.

Array
  .{...ArrayPrototype methods}

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 timers. Additional arguments fix for IE9-.

setTimeout(fn(...args), time, ...args) -> id
setInterval(fn(...args), time, ...args) -> id

// Before:
setTimeout(log.bind(null, 42), 1000);
// After:
setTimeout(log, 1000, 42);

setImmediate

Module immediate. setImmediate polyfill.

setImmediate(fn(...args), ...args) -> id
clearImmediate(id) -> void

Example:

setImmediate(function(arg1, arg2){
  console.log(arg1, arg2); // => Message will be displayed with minimum delay
}, 'Message will be displayed', 'with minimum delay');

clearImmediate(setImmediate(function(){
  console.log('Message will not be displayed');
}));

Console

Module console. Console cap for old browsers and some additional functionality.

console
  .{...console API}
  .enable() -> void
  .disable() -> void

// Before:
if(window.console && console.log)console.log(42);
// After:
console.log(42);

// Before:
setTimeout(console.log.bind(console, 42), 1000);
[1, 2, 3].forEach(console.log, console);
// After:
setTimeout(console.log, 1000, 42);
[1, 2, 3].forEach(console.log);

console.disable();
console.warn('Console is disabled, you will not see this message.');
console.enable();
console.warn('Console is enabled again.');

Object

Module object.

Object
  .isObject(var) -> bool
  .classof(var) -> string 
  .define(target, mixin) -> target
  .make(proto | null, mixin?) -> object

Object classify examples:

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:

// 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);
console.log(vector.xy);  // => 15
console.log(vector.xyz); // => 25
vector.y++;
console.log(vector.xy);  // => 15.811388300841896
console.log(vector.xyz); // => 25.495097567963924

Dict

Module dict. Based on TC39 discuss / strawman.

[new] Dict(itarable (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
  .turn(object, fn(memo, val, key, @), memo = new @) -> memo

Dict create object without prototype from iterable or simple object. Example:

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 return iterators for objects, examples:

var dict = {a: 1, b: 2, c: 3};

for(var key of Dict.keys(dict))console.log(key); // => 'a', 'b', 'c'

for(var [key, val] of Dict.entries(dict)){
  console.log(key); // => 'a', 'b', 'c'
  console.log(val); // => 1, 2, 3
}

$for(Dict.values(dict)).of(console.log); // => 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}

Other methods of Dict module are static equialents of Array.prototype methods for dictionaries, examples:

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'

Dict.turn(dict, function(memo, it, key){
  memo[key + key] = it;
});     // => {aa: 1, bb: 2, cc: 3}
Dict.turn(dict, function(memo, it, key){
  it % 2 && memo.push(key + it);
}, []); // => ['a1', 'c3']

Partial application

Module binding.

Function
  #part(...args | _) -> fn(...args)
  #by(object | _, ...args | _) -> boundFn(...args)
  #only(num, that /* = @ */) -> (fn | boundFn)(...args)
Object
  #[_](key) -> boundFn

Function#part partial apply function without this binding. Uses global variable _ (core._ for builds without extension of native objects) as placeholder. Examples:

var fn1 = console.log.part(1, 2);
fn1(3, 4);    // => 1, 2, 3, 4

var fn2 = console.log.part(_, 2, _, 4);
fn2(1, 3);    // => 1, 2, 3, 4

var fn3 = console.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

Method Function#by is analogue of Function#bind with the ability to use placeholder:

var fn = console.log.by(console, _, 2, _, 4);
fn(1, 3, 5); // => 1, 2, 3, 4, 5

Method Object#[_] extracts bound method from object, examples:

['foobar', 'foobaz', 'barbaz'].filter(/bar/[_]('test')); // => ['foobar', 'barbaz']

var has = {}.hasOwnProperty[_]('call');

log(has({key: 42}, 'foo')); // => false
log(has({key: 42}, 'key')); // => true

var array = []
  , push  = array[_]('push');
push(1);
push(2, 3);
log(array); // => [1, 2, 3];

Method Function#only limits number of arguments. Example:

[1, 2, 3].forEach(log.only(1)); // => 1, 2, 3

Date formatting

Module date. Much more simple and compact (~60 lines with en & ru locales) than Intl or Moment.js. Use them if you need extended work with Date.

Date
  #format(str, key?) -> str
  #formatUTC(str, key?) -> str
core
  .addLocale(key, object) -> core
  .locale(key?) -> key

Token	Unit	Sample
s	Seconds	0-59
ss	Seconds, 2 digits	00-59
m	Minutes	0-59
mm	Minutes, 2 digits	00-59
h	Hours	0-23
hh	Hours, 2 digits	00-23
D	Date	1-31
DD	Date, 2 digits	01-31
W	Weekday, string	Вторник
N	Month	1-12
NN	Month, 2 digits	01-12
M	Month, string	Ноябрь
MM	Of month, string	Ноября
Y	Year, full	2014
YY	Year, 2 digits	14
Examples:

new Date().format('W, MM D, YY, h:mm:ss');        // => 'Friday, November 28, 14, 18:47:05'
new Date().formatUTC('W, MM D, YY, h:mm:ss');     // => 'Friday, November 28, 14, 12:47:05'

new Date().format('W, D MM Y г., h:mm:ss', 'ru'); // => 'Пятница, 28 Ноября 2014 г., 18:07:25'

core.locale('ru');
new Date().format('W, D MM Y г., h:mm:ss');       // => 'Пятница, 28 Ноября 2014 г., 18:07:25'

new Date().format('DD.NN.YY');         // => '28.11.14'
new Date().format('hh:mm:ss');         // => '18:47:05'
new Date().format('DD.NN.Y hh:mm:ss'); // => '28.11.2014 18:47:05'
new Date().format('W, D MM Y года');   // => 'Пятница, 28 Ноября 2014 года'
new Date().format('D MM, h:mm');       // => '28 Ноября, 16:47'
new Date().format('M Y');              // => 'Ноябрь 2014'

(typeof core != 'undefined' ? core : require('core-js/library')).addLocale('ru', {
  weekdays: 'Воскресенье,Понедельник,Вторник,Среда,Четверг,Пятница,Суббота',
  months: 'Январ:я|ь,Феврал:я|ь,Март:а|,Апрел:я|ь,Ма:я|й,Июн:я|ь,Июл:я|ь,Август:а|,Сентябр:я|ь,Октябр:я|ь,Ноябр:я|ь,Декабр:я|ь'
});

Array

Module array.

Array
  #turn(fn(memo, val, index, @), memo = []) -> memo

Method Array#turn reduce array to object, example:

[1, 2, 3, 4, 5].turn(function(memo, it){
  memo['key' + it] = !!(it % 2);
}, {}); // => {key1: true, key2: false, key3: true, key4: false, key5: true}

[1, 2, 3, 4, 5, 6, 7, 8, 9].turn(function(memo, it){
  it % 2 && memo.push(it * it);
  if(memo.length == 3)return false;
}); // => [1, 9, 25]

Number

Module number.

Number
  #@@iterator() -> iterator
  #random(lim = 0) -> num
  #{...Math} 

Number Iterator examples:

for(var i of 3)console.log(i); // => 0, 1, 2

$for(3).of(console.log); // => 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}

$for(10).filter(function(i){
  return i % 2;
}).array(function(i){
  return i * i;
});  // => [1, 9, 25, 49, 81]

Dict($for(3).map(function(i){
  return ['key' + i, !(i % 2)];
})); // => {key0: true, key1: false, key2: true}

Math methods in Number.prototype examples:

3..pow(3);           // => 27
(-729).abs().sqrt(); // => 27

10..random(20);         // => Random number (10, 20), for example, 16.818793776910752
10..random(20).floor(); // => Random integer [10, 19], for example, 16

var array = [1, 2, 3, 4, 5];
array[array.length.random().floor()]; // => Random element, for example, 4

Escaping characters

Module string.

String
  #escapeHTML() -> str
  #unescapeHTML() -> str

Examples:

'<script>doSomething();</script>'.escapeHTML(); // => '&lt;script&gt;doSomething();&lt;/script&gt;'
'&lt;script&gt;doSomething();&lt;/script&gt;'.unescapeHTML(); // => '<script>doSomething();</script>'

Install

// Node.js:
npm i core-js
// Bower:
bower install core.js

Browser builds: default, without extension of native objects, shim only.

Custom builds:

npm i -g grunt-cli
npm i core-js
cd node_modules/core-js && npm i
grunt build:date,console,library --path=custom uglify

Where date and console are module names, library is flag for not extension of native objects and custom is target file name.

Require in Node.js:

// Dafault
require('core-js');
// Without extension of native objects
var core = require('core-js/library');
// Shim only
require('core-js/shim');

Changelog

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 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 excluded from node.js default builds

0.3.2 - 2014.12.25

• added cap for ES5 freeze-family methods
• fixed console bug

0.3.1 - 2014.12.23 - Some fixes

0.3.0 - 2014.12.23 - Optimize Map & Set

• use entries chain on hash table
• fast & correct iteration
• iterators moved to es6 and es6_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

• some fixes
• added Math.fround (IE10+)

0.2.3 - 2014.12.15 - Symbols:

• 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 - ES6:

• added RegExp#flags (December 2014 Draft Rev 29)
• added String.raw

0.2.1 - 2014.12.12 - Repair converting -0 to +0 in native collections

0.2.0 - 2014.12.06

• added es7, es7_refs modules
• added String#at
• added real String Iterator, 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 - ES6:

• added Array#copyWithin
• added String#codePointAt
• added String.fromCodePoint

0.1.4 - 2014.11.27

• added Dict.mapPairs

0.1.3 - 2014.11.20 - TC39 November meeting:

• .contains -> .includes
  • String#contains -> String#includes
  • Array#contains -> Array#includes
  • Dict.contains -> Dict.includes
• removed WeakMap#clear
• removed WeakSet#clear

0.1.2 - 2014.11.19 - Map & Set bug fix

0.1.1 - 2014.11.18 - Public release