Skip navigation

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.
NameSpace.Singleton.getInstance().publicMethod1();
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: