3.
Express JS-Cookies, Sessions, Authentication
a. Write a program for session management using cookies and sessions
Step-1:
Open VS Code and open (or create) your project folder
Step-2:
Open integrated terminal
• The terminal opens at your project folder path.
Step-3:
Initialize npm and install dependencies
Run these commands in the terminal:
• npm init -y
• npm install express express-session
Step-4:
• In VS Code explorer, click New File.
• Name it app.js.
• Paste the following code inside app.js:
const express = require('express');
const session = require('express-session');
const app = express();
const port = 3000;
app.use(session({
secret: 'mySecretKey123',
resave: false,
saveUninitialized: true,
cookie: { maxAge: 60000 }
}));
app.use(express.urlencoded({ extended: true }));
app.get('/', (req, res) => {
if (req.session.views) {
req.session.views++;
res.send(`<h1>Session Demo</h1>
<p>You visited this page ${req.session.views} times.</p>
<p><a href="/logout">Logout</a></p>`);
} else {
req.session.views = 1;
res.send(`<h1>Welcome! This is your first visit.</h1>
<p><a href="/">Refresh</a> | <a href="/logout">Logout</a></p>`);
}
});
app.get('/logout', (req, res) => {
req.session.destroy(err => {
if (err) {
return res.send('Error logging out');
}
res.clearCookie('connect.sid');
res.send('<h1>Logged out</h1><p><a href="/">Login again</a></p>');
});
});
app.listen(port, () => {
console.log(`Server started on http://localhost:${port}`);
});
Step-5:
In the terminal inside VS Code, run:
• node app.js
You should see:
• Server started on http://localhost:3000
Step-6:
Open your browser and visit:
http://localhost:3000
Output:
b. write a program for user authentication
Step-1:
Open VS Code and open (or create) your project folder
Step-2:
Open integrated terminal
• The terminal opens at your project folder path.
Step-3:
Initialize npm and install dependencies
Run these commands in the terminal:
• npm init -y
• npm install express express-session
• npm install bcryptjs
Step-4:
• In VS Code explorer, click New File.
• Name it app.js.
• Paste the following code inside app.js:
const express = require('express');
const session = require('express-session');
const bcrypt = require('bcrypt');
const app = express();
const port = 3000;
const users = [];
app.use(express.urlencoded({ extended: true }));
app.use(session({
secret: 'secretKey123',
resave: false,
saveUninitialized: false,
}));
function isAuthenticated(req, res, next) {
if (req.session.userId) {
next();
} else {
res.redirect('/login');
}
}
app.get('/', (req, res) => {
if (req.session.userId) {
res.send(`
<h1>Welcome user!</h1>
<p><a href="/protected">Go to protected page</a></p>
<p><a href="/logout">Logout</a></p>
`);
} else {
res.send(`
<h1>Home</h1>
<p><a href="/login">Login</a> | <a href="/register">Register</a></p>
`);
}
});
app.get('/register', (req, res) => {
res.send(`
<h1>Register</h1>
<form method="POST" action="/register">
<input name="username" placeholder="Username" required /><br/>
<input name="password" type="password" placeholder="Password" required
/><br/>
<button type="submit">Register</button>
</form>
<p><a href="/">Home</a></p>
`);
});
app.post('/register', async (req, res) => {
const { username, password } = req.body;
if (users.find(u => u.username === username)) {
return res.send('User already exists. <a href="/register">Try again</a>');
}
const hashedPassword = await bcrypt.hash(password, 10);
users.push({ username, password: hashedPassword });
res.send('Registration successful! <a href="/login">Login now</a>');
});
app.get('/login', (req, res) => {
res.send(`
<h1>Login</h1>
<form method="POST" action="/login">
<input name="username" placeholder="Username" required /><br/>
<input name="password" type="password" placeholder="Password" required
/><br/>
<button type="submit">Login</button>
</form>
<p><a href="/">Home</a></p>
`);
});
app.post('/login', async (req, res) => {
const { username, password } = req.body;
Output:
