Part of my blog post Revisiting Singleton Design Pattern : https:///insertafter.com

SimpleSingleton.js

// Singleton pattern
var MySingleton=(function() {
	// creating a variable to contain the instance
	var instance=null;
	// here goes private stuff
	var _myPrivateVar=1;
	var _myPrivateFunction=function(){
		console.log('In private function.');
	};
	// creating singleton constructor
	function Constructor() {
		// assigning instance to our variable
		instance=this;
	}
	// here goes public method and properties
	Constructor.prototype.publicProperty=1;
	Constructor.prototype.publicMethod=function() {
		console.log('In public method.');
		_myPrivateFunction();
	};
	// creating a constructor to generate an exception
	var FakeContructor=function() {
		throw SyntaxError('Singleton : Use getInstance instead.');
	}
	// associating him getInstance()
	FakeContructor.getInstance=function(){
			return instance || new Constructor();
		};
	return FakeContructor;
})();

// Usage
var singleton=MySingleton.getInstance();
console.log(singleton===MySingleton.getInstance()
	&&singleton===MySingleton.getInstance()
	&&singleton===MySingleton.getInstance());
// true
console.log(singleton.publicProperty);
// 1
singleton.publicMethod();
// In public method.
// In private function.


// Misuse attempts
var singleton=new MySingleton();
// SyntaxError : Singleton : Use getInstance instead.