1. Introduction

In this tutorial, we aim to guide you through managing cookies in Express.js. Cookies are a critical part of maintaining state between server and client requests. By the end of this tutorial, you will be able to create, read, update, and delete cookies using Express.js.

Before beginning, you should have a basic understanding of JavaScript, Node.js, and Express.js.

2. Step-by-Step Guide

Express.js doesn't handle cookies by default, we need to use a middleware called cookie-parser.

First, install cookie-parser:

npm install cookie-parser

After installing cookie-parser, we can include it in our application:

const express = require('express');
const cookieParser = require('cookie-parser');

const app = express();
app.use(cookieParser());

Now we are ready to manage cookies.

Creating Cookies

You can create cookies using the response.cookie() function. This function accepts three parameters: cookie name, cookie value, and options object.

app.get('/set', (req, res) => {
   res.cookie('cookieName', 'cookieValue', {expire: 360000 + Date.now()});
   res.send('Cookie is set');
});

Reading Cookies

Cookies can be read from the request.cookies object.

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

Updating Cookies

Updating a cookie can be done by setting the cookie again with the new value.

app.get('/update', (req, res) => {
   res.cookie('cookieName', 'newCookieValue', {expire: 360000 + Date.now()});
   res.send('Cookie updated');
});

Deleting Cookies

You can delete cookies using the response.clearCookie() function.

app.get('/clear', (req, res) => {
   res.clearCookie('cookieName');
   res.send('Cookie cleared');
});

3. Code Examples

Here is a complete example demonstrating all the actions we can perform on cookies.

const express = require('express');
const cookieParser = require('cookie-parser');

const app = express();
app.use(cookieParser());

// Set a new cookie
app.get('/set', (req, res) => {
   res.cookie('myCookie', 'express', {expire: 360000 + Date.now()});
   res.send('Cookie has been set');
});

// Get all cookies
app.get('/get', (req, res) => {
   res.send(req.cookies);
});

// Update a cookie
app.get('/update', (req, res) => {
   res.cookie('myCookie', 'updatedExpress', {expire: 360000 + Date.now()});
   res.send('Cookie has been updated');
});

// Clear a cookie
app.get('/clear', (req, res) => {
   res.clearCookie('myCookie');
   res.send('Cookie has been cleared');
});

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

4. Summary

In this tutorial, we have covered how to manage cookies in Express.js. We learned how to create, read, update, and delete cookies using cookie-parser middleware.

To continue learning, you can explore more about cookie options like HttpOnly, Secure, Domain, Path, and SameSite.

Additional resources:
- Express.js Documentation
- MDN Web Docs on HTTP Cookies

5. Practice Exercises

1. Create an Express.js server that sets a user's name in a cookie.
2. Update the previous exercise to display a welcome message to the user using the value in the cookie.
3. Create an Express.js server that sets a counter in a cookie. Every time a user visits the site, increment the counter.

Solutions and explanations will be provided upon request. You can explore more about cookies and their options for more practice.