Server middleware checks the token?

Short answer: 📌 Middleware example: function auth(req, res, next) { const token = req.headers.authorization?.split(' ')[1]; if (!token) return res.status(401).send('Unauthorized'); try { const user = jwt.verify(token, 'secret'); req.user = user; next(); } catch { res.status(403).send('Invalid token'); } }

Example code

📌 Middleware example: function auth(req, res, next) { const token = req.headers.authorization?.split(' ')[1];
if (!token) return res.status(401).send('Unauthorized'); try { const user = jwt.verify(token, 'secret');
req.user = user; next(); } catch { res.status(403).send('Invalid token'); }
}

Real-world example (ShopNest)

Express middleware authenticates JWT, then the /orders route handler creates the order.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.