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-es6require("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-
Symbolfor()keyFor@@hasInstance@@isConcatSpreadable@@iterator@@toStringTagSymbol.prototype.toString()Symbol.prototype.valueOf()
-
FunctionFunction.prototype[@@hasInstance]()
-
ArrayArray.prototype.concat()(ES6 version, addition of@@isConcatSpreadablesupport)Array.prototype[@@iterator]()Array.from()Array.prototype.entries()Array.prototype.keys()
-
ObjectObject.prototype.toString()(ES6 version, addition of@@toStringTagsupport)
-
StringString.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 ofinstanceOf)forOf()(This method behaves exactly same as ES6for...ofloop)spreadOperator(Gives same functionality of thespread operatorof ES6)
Your PRs and stars are always welcome.
Please, try to follow:
- Clone the repository.
- Checkout
developbranch. - Install dependencies.
- Add your new features or fixes.
- Build the project.
$ git clone https://github.com/rousan/symbol-es6.git
$ cd symbol-es6
$ git checkout develop
$ npm i
$ npm run build
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