How can I implement user authentication in an Express.js app?

How can I implement user authentication in an Express.js app?

You can use libraries like Passport.js or JWT for user authentication in Express.js. Would you like a code example?

Yes, please provide a code example using Passport.js.

Sure! First, install Passport and its dependencies. Then, set up a local strategy for username and password authentication. Here's a basic example:

const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;

passport.use(new LocalStrategy((username, password, done) => {
    // Find user in your database and verify password
}));

What about using JWT instead of sessions?

Using JWT is a great choice for stateless authentication. You can sign a token upon login and send it to the client. Here's a simple example:

const jwt = require('jsonwebtoken');

app.post('/login', (req, res) => {
    const token = jwt.sign({ userId: user.id }, 'your_jwt_secret');
    res.json({ token });
});