Multiton design pattern in ES6

Question

I want to create Multiton Design Pattern as part of my user module in my node.js application. And I need good examples of it.

Answer 1

Ok I have found answer by myself

class User {
    constructor(user_id) {
        console.log('constructor');
        this.user_id = user_id;
    }
}

const map = new Map();

const user_factory = {
    get_user(user_id) {
        let user = map.get(user_id);
        if (user === undefined) {
            user = new User(user_id);
            map.set(user_id, user);
        }
        return user;
    }
};

module.exports = user_factory;