Building APIs with Express

Introduction to Express

Express.js is a minimal, unopinionated web framework for Node.js. It provides the tools needed to build web applications and APIs without imposing structure.

Setting Up Express

Install Express and start building:

npm install express
  const express = require('express');
  const app = express();
  app.listen(3000, () => console.log('Server running on port 3000'));

Routing

Define routes for different HTTP methods:

app.get('/users', (req, res) => {
    res.json({ users: [] });
  });

  app.post('/users', (req, res) => {
    // Create user logic
    res.status(201).json({ message: 'User created' });
  });

Middleware

Middleware functions can execute code, modify requests/responses, or end the request cycle. Use built-in middleware for parsing JSON:

app.use(express.json());

Create custom middleware for authentication, logging, or CORS handling.

Error Handling

Implement error handling middleware at the end of your middleware stack:

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

Best Practices

• Use middleware for cross-cutting concerns
• Structure routes logically (group related routes)
• Validate input using libraries like Joi or express-validator
• Implement rate limiting to prevent abuse
• Use environment variables for configuration

Express provides a solid foundation for building scalable APIs. Combine it with databases like MongoDB or PostgreSQL for full-stack applications.