Express.js ist das meistverbreitete Node.js-Framework. Minimalistisch, flexibel, riesiges Middleware-Ökosystem.
Grundlegende API¶
const express = require(‘express’); const app = express(); app.use(express.json()); const items = []; app.get(‘/api/items’, (req, res) => { res.json(items); }); app.post(‘/api/items’, (req, res) => { const item = { id: items.length + 1, …req.body }; items.push(item); res.status(201).json(item); }); app.listen(3000, () => console.log(‘Server on :3000’));
Middleware¶
// Logging middleware
app.use((req, res, next) => {
console.log(${req.method} ${req.path});
next();
});
// Auth middleware
const auth = (req, res, next) => {
const token = req.headers.authorization?.split(’ ‘)[1];
if (!token) return res.status(401).json({ error: ‘Unauthorized’ });
req.user = verifyToken(token);
next();
};
app.get(‘/api/profile’, auth, getProfile);
Wichtigste Erkenntnis¶
Express = Routing + Middleware. Jede Middleware ruft next() auf. Error-Middleware hat 4 Parameter.