Singleton Pattern in JavaScript

What is Singleton Pattern?

The singleton pattern is a design pattern that restricts the instantiation of a class to one object, much inspired from singleton set {0}.

Where is it useful?

• Controlling concurrent access to a shared resource.

• Abstract Factory implementation.

• One time read variables. etc

What is the use of it?

Well despite the arguments and down votes for Singleton Pattern, it’s still surviving! And in JS it’s useful for :

• Encapsulation of members & functions.

• Creating Namespace.

• Encourages code reuse.

• Logically organisation of code gets easier.

Singleton implementation with JavaScript :

function SalarySingleton() {

if (typeof Singleton.salary === ‘object’) {

return Singleton.salary;

}

this.setSalary = function(amt) {

this.amt = amt;

} this.getSalary = function() {

return this.amt;

}

Singleton.salary = this;

}

var emp1 = new SalarySingleton(); emp1.setSalary(60000);

Do express your <3 towards singleton pattern!

EDIT 0 : iife to avoid new.

var singleton = (function () {

var amt; 
return { 
    getSalary: function () { return amt; }, 
    setSalary: function (amount) { amt = amount; }}; 
}

());