Express-session middleware in Express?

Express-session is an Express.js middleware that manages user sessions, storing user-specific data on the server and tracking it via cookies. It’s commonly used for login persistence, authentication, and maintaining state across multiple requests.

Steps to Use Express-session Middleware

Follow these steps to set up and use express-session for managing user sessions in your Express app.

Step 1: In the first step, we will create the new folder by using the below command in the VS Code terminal.

mkdir folder-name
cd folder-name

Step 2: After creating the folder, initialize the NPM using the below command. Using this the package.json file will be created.

npm init-y

Step 3: Now, we will install the express dependency for our project using the below command.

npm i express

Step 4: As we need to use the express-session middleware, we need to install it using npm. So for this article, we will be using third-party middleware as a express-session. So install it using the below command.

npm i express-session

Project Structure:

The updated dependencies in package.json file will look like.

"dependencies": {
    "express": "^4.18.2",
    "express-session": "^1.17.3"
}

Example: Write the following code in App.js file

//app.js
const express = require('express');
const session = require('express-session');
const app = express();
const port = 3000;
// setting the session middleware
app.use(session({
    secret: 'gfg-key',
    resave: false,
    saveUninitialized: true
}));
// set session in the / route
app.get('/', (req, res) => {
    // session variable
    req.session.gfgUser = 'geeksforgeeks';
    res.send(`Hey Geek! Session is set! Now Go to 
        <a href="/get">/get</a> to retrieve the session.`);
});
// get session in the /get route
app.get('/get', (req, res) => {
    // retrieve the session variable
    const gfgUser = req.session.gfgUser || 'No session set';
    res.send(`Session variable: ${gfgUser}`);
});
app.listen(port, () => {
    console.log(`Server is running on http://localhost:${port}`);
});

To run the application, we need to start the server by using the below command.

node app.js

Output: