class test 

{

    constructor()

    {

        console.log("new object created");

        this.test = { arr : {} };

    }

​

    static init()

    {

      return new test();

    }

​

    add()

    {

        let user_id = Math.floor(Math.random() * 10000);

        if(this.test.arr["u_" + user_id] === undefined)

        {

            this.test.arr["u_" + user_id] = [];

        }

        this.test.arr["u_" + user_id].push({"somedata": "here"});

​

        console.log("new item added - " + this.length() + " items ttl");

    }

​

    length()

    {

      return Object.keys(this.test.arr).length;

    }

​

}

​

var x = test.init();

x.add();

x.add();

console.log(x.length());

console.log(JSON.stringify(x));