Cookies

What is Cookie?

Cookies are small pieces of data stored on a user's device by websites they visit. They serve various purposes in web development.

Example Cookies use cases.

1. Session Management

2. Personalization

3. Tracking and Analytics

4. Advertising

5. Shopping Carts

6. Security

EX: Find cookies in YouTube.

1. open dev tools in YouTube tab. (Usually use F12 to open it.) 
2. go to Application tab.

   

3. Here's your YouTube cookies information is displayed.

   

   
   

    

Try Using cookies in your web server.

1. Init your server project
Here I will teach you how to create a project by terminal.
(windows PowerShell in windows or bash, sh, zsh in MacOS & Linux)
You can also create it in your comfortable ways.

1.  Create your project folder and enter it with: 

   mkdir backend_w3
   cd backend_w3
   
   # for mac users (sh, bash and etc..) you can use && to sequently run the commands
   mkdir backend_w3 && cd backend_w3
   # for windows PowerShell use ; instead
   mkdir backend_w3 ; cd backend_w3

   mkdir -> make directory (AKA folder)
   cd -> change working directory (AKA change folder)
   
   
2. Initialize your project and install node modules dependencies with  npm:

   npm init -y
   npm i express nodemon

   -y is for accept all default configurations.
   
   

3. Create index.js as main server file.

   const express = require('express');
   
   const app = express();
   const port = 4000;
   
   app.get('/', (req, res) => res.send('Hello World!'));
   
   app.listen(port, () => console.log(`Server running on port ${port}`));
   

4. Create an endpoint for sending cookie in index.js before app.listen:

   app.get('/getCookie', (req, res) => {
   	try {
   		const name = 'MyCookie';
   		const value = 'This is my cookie';
   		res.cookie(name, value);
   		return res.send('Cookie set');
   	} catch (error) {
   		console.log(error);
   		return res.status(500).send('Cookie not set');
   	}
   });

5. Now let's run our server. As some of you saw on the dependencies there is one new deps we install called nodemon. From the beginning us mentors tell you to run the server with node index.js and you have to always restart the server yourself every time you edited something now that where's nodemon solve this issue. Nodemon is a node dependency that use for running the node and automatically restart the node server by itself every time the codes are updated. Now let's try nodemon index.js instead. Or if some of you need to go further by using npm run dev as a running command you can go edit the package.json file here:
   Add the "dev": "nodemon index.js" in script section. And don't forget to add the ,(comma) on the above line if there're any.
6. Now you if you go to localhost:4000/getCookie and inspect it you will see your cookie there.
   

   

7. But as you see your cookies information is not private and that is some critical privacy issue due to the use cases of cookies sometime store sensitive information of users or even our own website. So, we're heading to our next topic: JWT