Shopfront Guide

npm install
export DATABASE_URL=postgres://localhost:5432/shopfront   # your local database
npm run dev        # API on :4000, client on :5173

const request = require('supertest');
const app = require('../server');
test('rejects an empty cart', async () => {
  await request(app).post('/api/orders').send({ items: [] }).expect(400);
});

const express = require('express');
const app = express();
app.use(express.json());                 // req.body for JSON requests

const items = express.Router();
app.use('/api/items', items);            // items' routes live under /api/items

module.exports = app;                    // export for tests; listen elsewhere

items.get('/:id', (req, res) => {
  res.json({ id: req.params.id, q: req.query.q });   // params are strings
});

items.post('/', (req, res) => {
  if (!req.body.name) return res.status(400).json({ error: 'name required' });
  res.status(201).json({ name: req.body.name });
});

function requireKey(req, res, next) {
  if (req.get('X-Example-Key') !== '<expected-value>') {
    return res.sendStatus(403);          // stop here
  }
  next();                                // pass to the next handler
}
app.use('/api/private', requireKey, privateRouter);

items.get('/:id/details', async (req, res, next) => {
  try {
    const item = await loadItem(req.params.id);  // your async lookup
    res.json(item);
  } catch (err) {
    next(err);                           // Express 4 won't do this for you
  }
});

app.use((err, req, res, next) => {     // four arguments, registered last
  res.status(err.status || 500).json({ error: 'something went wrong' });
});

const res = await fetch('/api/orders', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },   // needed for express.json()
  body: JSON.stringify({ items: [{ productId: 42, qty: 1 }] }),
});
if (!res.ok) throw new Error(`Order failed: ${res.status}`);  // fetch doesn't throw on 4xx/5xx
const { id } = await res.json();

curl http://localhost:4000/api/products/42
curl -X POST http://localhost:4000/api/orders \
  -H 'Content-Type: application/json' \
  -d '{"items": [{"productId": 42, "qty": 1}]}'

const request = require('supertest');
const app = require('../server');

test('GET an item', async () => {
  const res = await request(app).get('/api/items/42');
  expect(res.status).toBe(200);
  expect(res.body.id).toBe('42');
});

POST /api/orders HTTP/1.1
Content-Type: application/json

{"items": [{"productId": 42, "qty": 1}]}

const app = express();
app.use(express.json());
app.use('/api/products', products);
app.use('/api/orders', orders);
app.use('/api/admin', requireStaff, products.admin);

router.post('/', createOrder);
router.get('/:id', async (req, res) => res.json((await db.query('select * from orders where id=$1', [req.params.id])).rows[0]));

async function createOrder(req, res) {
  if (!Array.isArray(req.body.items) || !req.body.items.length) return res.status(400).json({ error: 'empty cart' });
  const { rows } = await db.query('insert into orders(items) values ($1) returning id', [JSON.stringify(req.body.items)]);
  res.status(201).json({ id: rows[0].id });
}

const { Pool } = require('pg');
module.exports = new Pool({ connectionString: process.env.DATABASE_URL });

npm test   # runs test/orders.test.js: POST /api/orders with an empty cart → 400

npm run dev   # API on :4000
curl -i -X POST http://localhost:4000/api/orders \
  -H 'Content-Type: application/json' -d '{"items": []}'   # → 400 {"error":"empty cart"}

router.post('/:id/cancel', async (req, res, next) => {
  try {
    const { rows } = await db.query('update orders set status = $2 where id = $1 returning id', [req.params.id, 'cancelled']);
    if (!rows[0]) return res.status(404).json({ error: 'no such order' });
    res.json({ id: rows[0].id, status: 'cancelled' });
  } catch (err) {
    next(err); // Express 4 won't do this for you
  }
});

test('cancel needs a real order', async () => {
  await request(app).post('/api/orders/999/cancel').expect(404);
});

npx codemod@latest @expressjs/v5-migration-recipe
npm install express@5 && npm test

npm run dev     # API + client, with hot reload
npm test        # Jest + Supertest
npm run lint    # ESLint
npm run build   # production client bundle