Node.js Examples

Express Basic Server

Create a simple Express server

const express = require('express');
const app = express();
const PORT = 3000;

app.get('/', (req, res) => {
  res.send('Hello from Express!');
});

app.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}`);
});

Middleware Usage

Example of logging middleware

app.use((req, res, next) => {
  console.log(`${req.method} ${req.url}`);
  next();
});

JWT Authentication Middleware

Protect routes with JWT verification

const jwt = require('jsonwebtoken');

function authMiddleware(req, res, next) {
  const token = req.headers['authorization'];
  if (!token) return res.status(401).send('Access denied');

  try {
    const verified = jwt.verify(token, process.env.JWT_SECRET);
    req.user = verified;
    next();
  } catch (err) {
    res.status(400).send('Invalid token');
  }
}

app.get('/protected', authMiddleware, (req, res) => {
  res.send('This is a protected route');
});