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

InheritSingleton.js

// Inherit JavaScript Singleton
function ParentConstructor() {}
ParentConstructor.prototype.publicProperty1=1;

var InheritSingleton=(function(parentConstructor) {
	// creating a variable to contain the instance
	var instance=null;
	// creating singleton constructor
	function Constructor() {
		// assigning instance to our variable
		instance=this;
	}
	// adding parent object to the singleton constructor prototype
	function F() {}
	F.prototype = (parentConstructor.getInstance?
		parentConstructor.getInstance():
		new parentConstructor()); 
	Constructor.prototype=new F();
	// here goes public method and properties
	Constructor.prototype.publicProperty2=2;
	Constructor.prototype.publicMethod2=function() {
		console.log('In public method 2.');
		_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;
})(ParentConstructor);

// Usage
var singleton=InheritSingleton.getInstance();
console.log(singleton.publicProperty1);
// 1
console.log(singleton.publicProperty2);
// 2