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Tag Archives: Javascript Lazy Load

In the previous post (JavaScript Singleton pattern), we saw the basic structure of JavaScript Singleton pattern. Then what is the need of JavaScript Lazy loading Singleton pattern? You can understand that JavaScript Singleton pattern which explain in previous post becomes performance issue if the code inside singleton object becomes more and more because the ananimous function executes immediately and returns properties, function, etc into singleton object immediately when .js files loads.

So it is wise to execute the function when it requires really. For that we need to define getInstance() method which checks to see whether the singleton has been instantiated. If not, it will instantiated and returned.  If it has, a stored copy is returned.

NameSpace.Singleton = (function(){
	var instance;
	function constructor() { // normal singlton goes here
		// Private members
		var privateAttr1 = false;
		var privateAtrr2 = [1,2,3];
		function privateMethod1(){
			// code goes here
		function privateMethod2(){args
			// code goes here
		return {  // Public members
			publicAttr1 : true;
			publicAttr2 : 25,
			publicMethod1 : function() {
				// code goes here
			publicMethod2 : function(args) {
				// code goes here
	return {
		getInstance : function(){
			if(!instance) {  // check already exists
				instance = constructor();
			return instance;

// Here is how the public function get called.