pricing.ts

  static priceFromCartChoices (rst: Rst, menuId: number, cartChoices: CartChoices, quantity: number) {
    const options = this.choicesCombined(rst, menuId).map(c => c.options).flat() as Options
    const ids = cartChoices.map(c => c.options).flat()
    const selects = options.filter(o => ids.includes(o.id) && o.price) as OptionsWithPrices
    const extras = selects.reduce((a, b) => a + b.price, 0)
    return (this.menuFromId(rst, menuId).price + extras) * quantity
  }