class Cart {
  items = [];
  discount = 0;
}
console.log(new Cart());

class Order {
  #total = 0;
  add(price) { this.#total += price; }
  get total() { return this.#total; }
}
const o = new Order();
o.add(220);
console.log(o.total, Object.keys(o));

class Order {
  static count = 0;
  constructor() { Order.count++; }
  static create() { return new Order(); }
}
Order.create();
Order.create();
console.log(Order.count);

class Menu {
  static prices = {};
  static {
    for (const [n, p] of [["Блокнот", 220], ["Пенал", 290]]) this.prices[n] = p;
  }
}
console.log(Menu.prices);

class Drink {
  constructor() {
    if (new.target === Drink) throw new Error("Только конкретный товар");
  }
}
class Latte extends Drink {}
console.log(new Latte() instanceof Drink);