Provides support for ES6
Symbol API in ES5
for older JS environments i.e. older browsers or NodeJS.
ES6 Symbol polyfill in pure ES5.
Install it from npm
and require
it before any other modules:
$ npm install --save symbol-es6
If you prefer CDN, then just insert it into your HTML page on the top of other scripts:
<script src="https://cdn.jsdelivr.net/npm/symbol-es6/dist/symbol-es6.min.js"></script>
"use strict"; var ES6 = require("symbol-es6"); console.log(Symbol("bar") === Symbol("bar")); //false var sym = Symbol.for("bar"); var sym2 = Symbol("bar"); console.log(Symbol.for("bar") === sym); //true console.log(sym === sym2); //false console.log(Symbol.keyFor(sym)); //bar console.log(Symbol.keyFor(sym2)); //undefined console.log(Array.from("Hello")); //[ 'H', 'e', 'l', 'l', 'o' ] var it = [1, 2].entries(); console.log(it.next()); //{ done: false, value: [ 0, 1 ] } console.log(it.next()); //{ done: false, value: [ 1, 2 ] } console.log(it.next()); //{ done: true, value: undefined } it = [1, 2].keys(); console.log(it.next()); //{ done: false, value: 0 } console.log(it.next()); //{ done: false, value: 1 } console.log(it.next()); //{ done: true, value: undefined } function Bar() { } console.log(Object.prototype.toString.call(new Bar())); //[object Object] Bar.prototype[Symbol.toStringTag] = "Bar"; console.log(Object.prototype.toString.call(new Bar())); //[object Bar] it = "Bar"[Symbol.iterator](); console.log(it.next()); //{ done: false, value: 'B' } console.log(it.next()); //{ done: false, value: 'a' } console.log(it.next()); //{ done: false, value: 'r' } console.log(ES6.isSymbol({})); //fasle console.log(ES6.isSymbol(sym)); ///true function Baz() { } console.log(ES6.instanceOf(89, Baz)); //false Object.defineProperty(Baz, Symbol.hasInstance, { value: function (value) { return typeof value === "number"; } }); console.log(ES6.instanceOf(89, Baz)); //true ES6.forOf([1, 2], function (v) { console.log(v); }); //1 //2 console.log(ES6.spreadOperator([]).spread("Bar").array()); //[ 'B', 'a', 'r' ] function TestSpread() { return Array.prototype.reduce.call(arguments, function (acc, currvalue) { return acc + currvalue; }, 0); } console.log(ES6.spreadOperator(TestSpread).spread([1, 2, 3, 4, 5]).call()); //15 function Student(name, roll) { this.name = name; this.roll = roll; } console.log(ES6.spreadOperator(Student).spread(["Ariyan", 10]).new().name); //Ariyan
Symbol
for()
keyFor
@@hasInstance
@@isConcatSpreadable
@@iterator
@@toStringTag
Symbol.prototype.toString()
Symbol.prototype.valueOf()
Function
Function.prototype[@@hasInstance]()
Array
Array.prototype.concat()
(ES6 version, addition of @@isConcatSpreadable
support)Array.prototype[@@iterator]()
Array.from()
Array.prototype.entries()
Array.prototype.keys()
Object
Object.prototype.toString()
(ES6 version, addition of @@toStringTag
support)String
String.prototype[@@iterator]()
Some ES6
features can't be implemented in ES5
natively like spread operator
, for..of
loop, ES6
version of instanceOf
operator etc. So this module exports a object named ES6
globally, that provides some approximate equivalent implementation of those features.
This object provides,
isSymbol()
(It can be used as equivalent API of: typeof symbol === 'symbol'
)instanceOf()
(Provides ES6 version of instanceOf
)forOf()
(This method behaves exactly same as ES6 for...of
loop)spreadOperator
(Gives same functionality of the spread operator
of ES6)Your PRs and stars are always welcome.
Please, try to follow:
develop
branch.$ git clone https://github.com/rousan/symbol-es6.git $ cd symbol-es6 $ git checkout develop $ npm i $ npm run build
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