Express JS Tutorial #13 – Introduction to Sessions

Introduction:
Express JS is a popular and powerful web application framework for Node.js. In this tutorial, we will be discussing how to implement sessions in Express JS, which is essential for maintaining user authentication and managing state between client and server. This is the first part of a two-part series on sessions in Express JS.

What are sessions?
Sessions are a way to store and manage user data across multiple requests. When a user logs into a web application, a session is created to store the user’s data, which can then be accessed throughout the user’s visit. Sessions are typically stored on the server and identified by a unique session ID.

Why are sessions important?
Sessions are important for maintaining user authentication and managing state between client and server. By using sessions, you can keep track of users who are logged in, store user-specific data, and prevent unauthorized access to certain parts of your application.

Setting up sessions in Express JS:
To start using sessions in Express JS, you need to install the ‘express-session’ package. You can do this by running the following command in your terminal:

npm install express-session

Once the package is installed, you can require it in your Express application and use it to set up sessions. Here’s how you can do that:

const express = require('express');
const session = require('express-session');

const app = express();

app.use(session({
  secret: 'your_secret_key',
  resave: false,
  saveUninitialized: false
}));

In the code above, we are creating a new session middleware using the express-session package. We are passing in an object with three options: secret, resave, and saveUninitialized.

• secret: This is a string that is used to sign the session cookie. It should be a random, long, and unique string to enhance security.
• resave: This option determines whether the session should be saved back to the session store if it hasn’t changed during the request. Set this to false to prevent unnecessary updates to the session.
• saveUninitialized: This option determines whether a session should be created for a new but unmodified session. Set this to false if you don’t want to save uninitialized sessions.

Accessing and updating session data:
Once you have set up sessions in your Express application, you can access and update session data using the req.session object. Here’s an example of how you can set and get session data:

app.get('/', (req, res) => {
  req.session.username = 'john.doe';
  res.send(`Welcome, ${req.session.username}`);
});

app.get('/profile', (req, res) => {
  const username = req.session.username;
  res.send(`Profile page for ${username}`);
});

In the code above, we are setting the username property in the session object to ‘john.doe’ when a user accesses the home route. We then retrieve the username property from the session object and display it on the profile page.

Conclusion:
In this tutorial, we have learned how to set up sessions in Express JS using the express-session package. We have also seen how to access and update session data in your Express application. Sessions are crucial for maintaining user authentication and managing state between client and server, making them an essential feature for web applications. In the next part of this series, we will explore more advanced topics related to sessions in Express JS.