Building Scalable APIs with Node.js and Express

src/
├── routes/
├── controllers/
├── middleware/
├── services/
└── utils/

import express from 'express';
import cors from 'cors';
import helmet from 'helmet';

const app = express();

app.use(helmet());
app.use(cors());
app.use(express.json());

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

import { Router } from 'express';

const router = Router();

router.get('/users', async (req, res) => {
  const users = await userService.findAll();
  res.json(users);
});

router.get('/users/:id', async (req, res) => {
  const user = await userService.findById(req.params.id);
  if (!user) {
    return res.status(404).json({ error: 'User not found' });
  }
  res.json(user);
});

export default router;

import { Request, Response, NextFunction } from 'express';

export function errorHandler(
  err: Error,
  req: Request,
  res: Response,
  next: NextFunction
) {
  console.error(err.stack);
  res.status(500).json({ error: 'Internal server error' });
}

import { z } from 'zod';

const createUserSchema = z.object({
  email: z.string().email(),
  name: z.string().min(2),
  password: z.string().min(8),
});

router.post('/users', async (req, res) => {
  const result = createUserSchema.safeParse(req.body);
  if (!result.success) {
    return res.status(400).json({ errors: result.error.issues });
  }
  const user = await userService.create(result.data);
  res.status(201).json(user);
});