examples/checkout.json

{
  "title": "A safer path from cart to order",
  "files": [
    {
      "path": "checkout.ts",
      "before": "import { OrderStore, Cart } from './orders';\n\n/** Turn the customer's cart into an order. */\nexport function placeOrder(cart: Cart) {\n  const store = new OrderStore();\n  const total = calculateTotal(cart);\n  return store.save(cart, total);\n}\n\n/** Add up the price of every item. */\nfunction calculateTotal(cart: Cart) {\n  return cart.items.reduce((sum, item) => sum + item.price, 0);\n}\n",
      "after": "import { OrderStore, Cart } from './orders';\n\n/** Turn the customer's cart into an order. */\nexport function placeOrder(cart: Cart) {\n  if (!hasItems(cart)) return { error: 'Your cart is empty' };\n  const store = new OrderStore();\n  const total = calculateTotal(cart);\n  return store.save(cart, total);\n}\n\n/** Check that there is something to order. */\nfunction hasItems(cart: Cart) {\n  return cart.items.length > 0;\n}\n\n/** Add up the price of every item, including its quantity. */\nfunction calculateTotal(cart: Cart) {\n  return cart.items.reduce((sum, item) => sum + item.price * item.quantity, 0);\n}\n"
    },
    {
      "path": "orders.ts",
      "before": "/** The items the customer wants to order. */\nexport interface Cart {\n  items: { name: string; price: number; quantity: number }[];\n}\n\n/** Keep the details of an order together. */\nexport class OrderStore {\n  /** Create an order record from a cart and its total. */\n  save(cart: Cart, total: number) {\n    return { items: cart.items, total, status: 'created' };\n  }\n}\n",
      "after": "/** The items the customer wants to order. */\nexport interface Cart {\n  items: { name: string; price: number; quantity: number }[];\n}\n\n/** Keep the details of an order together. */\nexport class OrderStore {\n  /** Create an order record from a cart and its total. */\n  save(cart: Cart, total: number) {\n    return { items: cart.items, total, status: 'created' };\n  }\n}\n"
    }
  ]
}