Simplest/Cleanest way to implement singleton in JavaScript?

Question

What is the simplest/cleanest way to implement singleton pattern in JavaScript?

Answer 1

If you want to use classes:

class Singleton {
  constructor(name, age) {
    this.name = name;
    this.age = age;
    if(this.constructor.instance)
      return this.constructor.instance;
    this.constructor.instance = this;
  }
}
let x = new Singleton('s',1);
let y = new Singleton('k',2);

Output for the above will be:

console.log(x.name,x.age,y.name,y.age) // s 1 s 1

Another way of writing Singleton using function

function AnotherSingleton (name,age) {
  this.name = name;
  this.age = age;
  if(this.constructor.instance)
    return this.constructor.instance;
  this.constructor.instance = this;
}

let a = new AnotherSingleton('s',1);
let b = new AnotherSingleton('k',2);

Output for the above will be:

console.log(a.name,a.age,b.name,b.age)// s 1 s 1