Private data from public methods in stampit

main.js

import User from './User';

const user_a = User();
const user_b = User();


console.log(user_a.getID());
console.log(user_a.getName());
console.log(user_b.getID());
console.log(user_b.getName());

User.js

import stampit from 'stampit';

let numUsers = 0;
let map = new WeakMap();

function setData(object, key, value) {
	let data = map.get(object);
	data[key] = value;
}

function getData(object, key) {
	let data = map.get(object);
	return data[key];
}

export default stampit().init(function() {
	map.set(this, {});
	setData(this, 'id', ++numUsers);
	setData(this, 'name', 'User ' + getData(this, 'id'));
}).methods({
	getID() {
		return getData(this, 'id');
	},
	getName() {
		return getData(this, 'name')
	}
});