Implementing Cookies in benhall/express-demo

Scenario:

You are building a web application using the benhall/express-demo project, and you need to manage cookies in your Express application. Cookies are small pieces of data that can be stored on the client-side by the browser and sent back to the server with each request. They are commonly used for session management, authentication, and storing user preferences.

Solution:

To implement cookies in your Express application built with benhall/express-demo, you will use a cookie middleware, configure the cookie options, and handle cookie data.

Step 1: Install the cookie-parser middleware First, you need to install the cookie-parser middleware, which is used to parse cookie headers into a JavaScript object. You can install it using npm by running the following command in your project directory:

npm install cookie-parser

Step 2: Import and use the cookie-parser middleware Next, import the cookie-parser middleware in your app.js file and use it as middleware:

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

const app = express();

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

Step 3: Set cookies To set cookies, you can use the res.cookie() method provided by the cookie-parser middleware. Here’s an example of setting a cookie named sessionId with a value of abc123 and a max age of one hour:

app.get('/set-cookie', (req, res) => {
res.cookie('sessionId', 'abc123', { maxAge: 3600000 });
res.send('Cookie set');
});

Step 4: Read cookies To read cookies, you can access them as properties of the req object:

app.get('/read-cookie', (req, res) => {
const sessionId = req.cookies.sessionId;
res.send(`Cookie value: ${sessionId}`);
});

Step 5: Delete cookies To delete cookies, you can set the maxAge property to a negative value:

app.get('/delete-cookie', (req, res) => {
res.cookie('sessionId', '', { maxAge: -1 });
res.send('Cookie deleted');
});

Tests:

To verify the implementation of cookies in your Express application, you can write tests using a testing framework like Mocha and Chai. Here’s an example of a test file that checks if cookies are set and read correctly:

const request = require('supertest')(app);
const assert = require('assert');

describe('Cookies', () => {
it('should set and read a cookie', async () => {
const res = await request.get('/set-cookie');
assert.strictEqual(res.text, 'Cookie set');

const res2 = await request.get('/read-cookie');
assert.notStrictEqual(res2.text, 'Cookie set');
assert.strictEqual(res2.text, `Cookie value: abc123`);
});

it('should delete a cookie', async () => {
await request.get('/set-cookie');
const res = await request.get('/read-cookie');
assert.strictEqual(res.text, `Cookie value: abc123`);

await request.get('/delete-cookie');
const res2 = await request.get('/read-cookie');
assert.strictEqual(res2.text, 'Cookie deleted');
});
});

Make sure to run your tests using a testing framework like Mocha and Chai to ensure that your implementation of cookies in your Express application is working correctly.