link: Session Management

Web Local Storage

Overview

Web local storage, also known as browser local storage, is a feature of HTML5 that allows Web applications to store data locally within the user’s browser. Unlike Cookies, which are sent with every HTTP request, local storage data is only accessible within the browser and is not transmitted to the server. This makes local storage a suitable option for storing data that needs to persist across sessions but doesn’t require server-side interaction.

How Web Local Storage Works

How Web Local Storage Works

1. Data Storage: Data is stored as key-value pairs in the browser’s storage space.
2. Access: JavaScript is used to read from and write to local storage.
3. Persistence: Data in local storage persists even after the browser is closed and reopened, until explicitly deleted.

Pros/Cons

Pros

• Persistence: Data remains available even after the browser is closed, providing a persistent storage solution.
• Size Limit: Offers a larger storage capacity compared to Cookies (typically up to 5MB per domain).
• Performance: Local storage operations are fast and do not affect network performance since data is not transmitted with HTTP requests.

Cons

• Security: Data stored in local storage can be accessed by any script running on the same domain, making it vulnerable to cross-site scripting (XSS) attacks.
• Limited Storage: Although larger than cookies, local storage still has storage limits that might not be sufficient for some applications.
• No Expiration: Unlike Cookies, local storage data does not expire automatically and must be managed by the application.

Common Use Cases

Use Cases

• Storing User Preferences: Saving user settings and preferences that persist across sessions.
• Offline Applications: Storing data locally for offline access and synchronization when the user is back online.
• Shopping Carts: Keeping track of items in a shopping cart across multiple sessions without requiring server interaction.

Implementation Example

Here’s a basic example of using web local storage with JavaScript:

Javascript

// Store data
localStorage.setItem('username', 'JohnDoe');
 
// Retrieve data
const username = localStorage.getItem('username');
console.log(username); // Output: JohnDoe
 
// Remove data
localStorage.removeItem('username');
 
// Clear all data
localStorage.clear();