Singleton

singleton.js

class Singleton {
  constructor() {
    if (Singleton._instance) {
      return Singleton._instance;
    }
    Singleton._instance = this;
  }

  someFunction = () => {
    console.log("I am a singleton");
  }
}

const s1 = new Singleton();
const s2 = new Singleton();
assert(s1 === s2);