Singleton ES6 class

class.js

let instance = null;

export class Cache{  
    constructor() {
        if(!instance){
              instance = this;
        }

        this.time = new Date()

        return instance;
      }
}

index.js

import {Cache} from './class.js';

 let cache = new Cache();
 console.log(cache.time);

 setTimeout(function() {
   let cache = new Cache();
   console.log(cache.time);
 },4000);