express-rest-api

Express REST API Skill

Master building robust, scalable REST APIs with Express.js, the de-facto standard for Node.js web frameworks.

Quick Start

Build a basic Express API in 5 steps:

Setup Express - npm install express Create Routes - Define GET, POST, PUT, DELETE endpoints Add Middleware - JSON parsing, CORS, security headers Handle Errors - Centralized error handling Test & Deploy - Use Postman/Insomnia, deploy to cloud Core Concepts 1. Express Application Structure const express = require('express'); const app = express();

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

// Routes app.use('/api/users', userRoutes); app.use('/api/products', productRoutes);

// Error handling app.use(errorHandler);

app.listen(3000, () => console.log('Server running'));

1. RESTful Route Design // GET /api/users - Get all users // GET /api/users/:id - Get user by ID // POST /api/users - Create user // PUT /api/users/:id - Update user // DELETE /api/users/:id - Delete user

const router = express.Router();

router.get('/', getAllUsers); router.get('/:id', getUserById); router.post('/', createUser); router.put('/:id', updateUser); router.delete('/:id', deleteUser);

module.exports = router;

1. Middleware Patterns // Authentication middleware const authenticate = (req, res, next) => { const token = req.headers.authorization; if (!token) return res.status(401).json({ error: 'Unauthorized' }); // Verify token... next(); };

// Validation middleware const validate = (schema) => (req, res, next) => { const { error } = schema.validate(req.body); if (error) return res.status(400).json({ error: error.message }); next(); };

// Usage router.post('/users', authenticate, validate(userSchema), createUser);

1. Error Handling // Custom error class class APIError extends Error { constructor(message, statusCode) { super(message); this.statusCode = statusCode; } }

// Global error handler app.use((err, req, res, next) => { const statusCode = err.statusCode || 500; res.status(statusCode).json({ success: false, error: err.message, ...(process.env.NODE_ENV === 'development' && { stack: err.stack }) }); });

Learning Path Beginner (2-3 weeks) ✅ Setup Express and create basic routes ✅ Understand middleware concept ✅ Implement CRUD operations ✅ Test with Postman Intermediate (4-6 weeks) ✅ Implement authentication (JWT) ✅ Add input validation ✅ Organize code (MVC pattern) ✅ Connect to database Advanced (8-10 weeks) ✅ API versioning (/api/v1/, /api/v2/) ✅ Rate limiting and security ✅ Pagination and filtering ✅ API documentation (Swagger) ✅ Performance optimization Essential Packages { "dependencies": { "express": "^4.18.0", "helmet": "^7.0.0", // Security headers "cors": "^2.8.5", // Cross-origin requests "morgan": "^1.10.0", // HTTP logger "express-validator": "^7.0.0", // Input validation "express-rate-limit": "^6.0.0" // Rate limiting } }

Common Patterns Response Format // Success { success: true, data: {...} }

// Error

// Pagination { success: true, data: [...], pagination: { page: 1, limit: 10, total: 100 } }

HTTP Status Codes 200 OK - Successful GET/PUT 201 Created - Successful POST 204 No Content - Successful DELETE 400 Bad Request - Validation error 401 Unauthorized - Auth required 403 Forbidden - No permission 404 Not Found - Resource not found 500 Internal Error - Server error Project Structure src/ ├── controllers/ # Route handlers ├── routes/ # Route definitions ├── middlewares/ # Custom middleware ├── models/ # Data models ├── services/ # Business logic ├── utils/ # Helpers └── app.js # Express setup

Production Checklist ✅ Environment variables (.env) ✅ Security headers (Helmet) ✅ CORS configuration ✅ Rate limiting ✅ Input validation ✅ Error handling ✅ Logging (Morgan/Winston) ✅ Testing (Jest/Supertest) ✅ API documentation Real-World Example

Complete user API:

const express = require('express'); const router = express.Router(); const { body } = require('express-validator');

// GET /api/users router.get('/', async (req, res, next) => { try { const { page = 1, limit = 10 } = req.query; const users = await User.find() .limit(limit) .skip((page - 1) * limit);

res.json({ success: true, data: users });

} catch (error) { next(error); } });

// POST /api/users router.post('/', body('email').isEmail(), body('password').isLength({ min: 8 }), async (req, res, next) => { try { const user = await User.create(req.body); res.status(201).json({ success: true, data: user }); } catch (error) { next(error); } } );

module.exports = router;

When to Use

Use Express REST API when:

Building backend for web/mobile apps Creating microservices Developing API-first applications Need flexible, lightweight framework Want large ecosystem and community Related Skills Async Programming (handle async operations) Database Integration (connect to MongoDB/PostgreSQL) JWT Authentication (secure your APIs) Jest Testing (test your endpoints) Docker Deployment (containerize your API) Resources Express.js Official Docs REST API Best Practices MDN HTTP Guide