Simulating ES6 Symbols In ES5
Symbols , previously known as Names , are a new way to add real private properties to a generic object. // basic Symbol example var BehindTheScene = (function(){ var symbol = new Symbol; function BehindTheScene(){ this[symbol] = {}; } BehindTheScene.prototype.get = function(k) { return this[symbol][k]; }; BehindTheScene.prototype.set = function(k, v) { return this[symbol][k] = v; }; return BehindTheScene; }()); var obj = new BehindTheScene; obj.set('key', 123); obj.key; // undefined obj.get('key'); // 123 In few words symbol makes possible to attach properties directly without passing through a WeakMap. A similar behavior could be obtained indeed via WeakMaps: // similar WeakMap example var BehindTheScene = (function(){ var wm = new WeakMap; function BehindTheScene(){ wm.set(this, {}); } BehindTheScene.prototype.get = function(k) { return wm.get(this)[k]; }; BehindTheScene.prototype.set = function(k, v) { return wm.get...