JavaScript Singleton using class

README.md

What the

Simple implementation of a Singleton Design Pattern in ES2016

ClassA.js

'use strict';
import Singleton from 'Singleton';

class ClassA extends Singleton {
    constructor() {
        super();
    }
    
    singletonMethod1() {
        // ...
    }
    
    singletonMethod2() {
        // ...
    }
    
    // ...
}

console.log(
    ClassA.instance === ClassA.instance,
    ClassA.instance === new ClassA,
    new ClassA === new ClassA
); // true, true, true

Singleton.js

'use strict';
const singleton = Symbol('singleton');

export default class Singleton {
    static get instance() {
        if(!this[singleton]) {
            this[singleton] = new this;
        }

        return this[singleton];
    }
    
    constructor() {
        let Class = new.target; // or this.constructor

        if(!Class[singleton]) {
            Class[singleton] = this;
        }

        return Class[singleton];
    }
}