Singleton Design Pattern JavaScript
JavaScript: Singleton Design Pattern with Real Time Example
Singleton Design Pattern:
It is Creational Patterns which focus on how to instantiate an object.
Singleton Design Pattern ensure that a class has only one instance, and provides a way to access it globally.
In other words, Singletons are used to create an instance of a class if it does not exist or else return the reference of the existing one.
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Singleton Design Pattern using IIFE
var Singleton = (function() {
var instance;
function createInstance() {
var object = new Object("I am the instance");
return object;
}
return {
getInstance: function() {
if (!instance) {
instance = createInstance();
}
return instance;
}
};
})();
function myFunc() {
var instance1 = Singleton.getInstance();
var instance2 = Singleton.getInstance();
console.log(instance1 === instance2);
}
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Singleton Design Pattern using ES6
class Singleton {
static instance;
constructor() {
if (instance) {
return instance;
}
this.state = "Singleton ES6";
this.instance = this;
}
}
export default Singleton;
let instance1 = new Singleton();
let instance2 = new Singleton();
console.log(instance1 === instance2);
//output: true