Building RESTful APIs with Node.js and Express

Node.js and Express provide a powerful combination for building scalable web APIs. In this guide, we'll create a complete RESTful API from scratch.

Setting Up Your Project

First, let's initialize a new Node.js project:

npm init -y
npm install express cors helmet morgan
npm install -D nodemon

Basic Express Server

Create a simple Express server:

const express = require('express');
const cors = require('cors');
const helmet = require('helmet');
const morgan = require('morgan');

const app = express();
const PORT = process.env.PORT || 3000;

// Middleware
app.use(helmet());
app.use(cors());
app.use(morgan('combined'));
app.use(express.json());

// Routes
app.get('/api/health', (req, res) => {
  res.json({ status: 'OK', timestamp: new Date().toISOString() });
});

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Creating RESTful Routes

Let's build a complete CRUD API for a "users" resource:

// In-memory storage (use a database in production)
let users = [
  { id: 1, name: 'John Doe', email: 'john@example.com' },
  { id: 2, name: 'Jane Smith', email: 'jane@example.com' }
];

// GET /api/users - Get all users
app.get('/api/users', (req, res) => {
  res.json(users);
});

// GET /api/users/:id - Get user by ID
app.get('/api/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) {
    return res.status(404).json({ error: 'User not found' });
  }
  res.json(user);
});

// POST /api/users - Create new user
app.post('/api/users', (req, res) => {
  const { name, email } = req.body;
  
  if (!name || !email) {
    return res.status(400).json({ error: 'Name and email are required' });
  }
  
  const newUser = {
    id: users.length + 1,
    name,
    email
  };
  
  users.push(newUser);
  res.status(201).json(newUser);
});

// PUT /api/users/:id - Update user
app.put('/api/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  
  if (!user) {
    return res.status(404).json({ error: 'User not found' });
  }
  
  const { name, email } = req.body;
  if (name) user.name = name;
  if (email) user.email = email;
  
  res.json(user);
});

// DELETE /api/users/:id - Delete user
app.delete('/api/users/:id', (req, res) => {
  const userIndex = users.findIndex(u => u.id === parseInt(req.params.id));
  
  if (userIndex === -1) {
    return res.status(404).json({ error: 'User not found' });
  }
  
  users.splice(userIndex, 1);
  res.status(204).send();
});

Error Handling Middleware

Add proper error handling:

// Error handling middleware
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ error: 'Something went wrong!' });
});

// 404 handler
app.use('*', (req, res) => {
  res.status(404).json({ error: 'Route not found' });
});

Testing Your API

Test your endpoints using curl or Postman:

# Get all users
curl http://localhost:3000/api/users

# Create a new user
curl -X POST http://localhost:3000/api/users \
  -H "Content-Type: application/json" \
  -d '{"name":"Bob Johnson","email":"bob@example.com"}'

# Update a user
curl -X PUT http://localhost:3000/api/users/1 \
  -H "Content-Type: application/json" \
  -d '{"name":"John Updated"}'

Best Practices

• Use environment variables for configuration
• Implement proper authentication and authorization
• Add input validation with libraries like Joi
• Use a real database (MongoDB, PostgreSQL, etc.)
• Implement rate limiting and security measures
• Add comprehensive logging and monitoring

This foundation will help you build robust APIs that can scale with your application needs!