Express.js Tutorial

Master Express.js fundamentals with our comprehensive tutorial. Learn through examples and hands-on practice.

Video Tutorial

Introduction to Express.js

Express.js is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

Examples:

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

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

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

A basic Express.js server setup

Express.js Routing

Routing refers to determining how your application responds to client requests to particular endpoints (URIs).

Examples:

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

// Handle GET request
app.get('/users', (req, res) => {
  res.json([{ name: 'John' }, { name: 'Jane' }]);
});

// Handle POST request
app.post('/users', (req, res) => {
  // Create new user
  res.status(201).send('User created');
});

// Route parameters
app.get('/users/:id', (req, res) => {
  res.send(`User ID: ${req.params.id}`);
});

Different types of route handlers in Express.js

Middleware in Express.js

Middleware functions are functions that have access to the request object, response object, and the next middleware function in the application's request-response cycle.

Examples:

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

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

// Use middleware
app.use(logger);

// Built-in middleware
app.use(express.json());
app.use(express.static('public'));

app.post('/api/data', (req, res) => {
  console.log(req.body); // Parsed JSON data
  res.json({ received: true });
});

Using built-in and custom middleware in Express.js