Node.js — Express

Installation

npm install express

Basic Express App

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

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

app.listen(3000, () => {
    console.log('Server running on port 3000');
});

Routing

// GET
app.get('/users', (req, res) => {
    res.json(users);
});

// POST
app.post('/users', (req, res) => {
    const user = req.body;
    users.push(user);
    res.status(201).json(user);
});

// PUT
app.put('/users/:id', (req, res) => {
    const id = parseInt(req.params.id);
    const user = users.find(u => u.id === id);
    Object.assign(user, req.body);
    res.json(user);
});

// DELETE
app.delete('/users/:id', (req, res) => {
    users = users.filter(u => u.id !== parseInt(req.params.id));
    res.sendStatus(204);
});

Middleware

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

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

Mini Practice

1. Create an Express app
2. Set up routes
3. Add middleware
4. Handle different HTTP methods

Up Next

Continue with Middleware — Express middleware patterns.