Node.js Express API Development

Last updated: 2025-09-25 12:47:03

Building APIs with Node.js and Express

Express.js is a fast, unopinionated web framework for Node.js, perfect for building RESTful APIs.

Basic Express Server

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

// Middleware
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// Routes
app.get('/', (req, res) => {
  res.json({ message: 'Welcome to our API!' });
});

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

CRUD Operations

// Sample data
let users = [
  { id: 1, name: 'John Doe', email: 'john@example.com' },
  { id: 2, name: 'Jane Smith', email: 'jane@example.com' }
];

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

// 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);
});

// CREATE new user
app.post('/api/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name,
    email: req.body.email
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

// 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' });
  
  user.name = req.body.name || user.name;
  user.email = req.body.email || user.email;
  res.json(user);
});

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

Error Handling Middleware

// 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' });
});