house.js

class House {
	constructor() {
  	this.rooms = [];
  }
  getRooms() {
  	return this.rooms;
  }
  addRoom(name, props) {
  	this.rooms.push({ name, props });
  }
}

const myHouse = new House();
// This is what you want ppl to do
myHouse.addRoom('master', { sqFt: 300 });
// The problem is, what's stopping someone
// from doing this?
// No private fields in JS..
myHouse.rooms.push("i am just a string");

console.log(myHouse.rooms)