Build HTTP APIs with routing, middleware, validation, controllers, and error handling.
Lessons
Choose between require and import module styles in an Express project.
ESM vs CommonJS in Express 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());
app.get('/api/lessons', (req, res) => {
res.json([{ slug: 'express-routing', title: 'Express Routing' }]);
});
app.post('/api/lessons', (req, res) => {
res.status(201).json({ created: true, title: req.body.title });
});
app.listen(process.env.PORT || 3000);Practice the ESM vs CommonJS in Express example in a small scratch file, then explain what changed and why.