Build HTTP APIs with routing, middleware, validation, controllers, and error handling.
Lessons
Version your API with URL prefixes or headers without breaking clients.
API Versioning is easiest to learn by reading the example, changing it, and observing the result.
import express from 'express';
const app = express();
app.use(express.json());
const lessons = [];
app.get('/api/v1/lessons', (req, res) => res.json({ data: lessons }));
app.post('/api/v1/lessons', (req, res) => {
const lesson = { id: lessons.length + 1, ...req.body };
lessons.push(lesson);
res.status(201).json({ data: lesson });
});
app.put('/api/v1/lessons/:id', (req, res) => res.json({ data: { id: req.params.id, ...req.body } }));
app.delete('/api/v1/lessons/:id', (req, res) => res.status(204).end());
app.listen(3000);Practice the API Versioning example in a small scratch file, then explain what changed and why.