XSS (Cross-Site Scripting) is one of the most common security attacks on web applications.
In an XSS attack, a hacker injects malicious JavaScript into a page so it runs in other users’ browsers.
Preventing XSS is a critical skill for every JavaScript developer because it protects users from data theft, session hijacking, and fake actions.
How XSS Attacks Happen
- When user input is displayed without validation
- When innerHTML is used carelessly
- When form data is trusted blindly
- When dynamic content is not sanitized
Any place that shows user data can become an attack point.
This code allows the script to run inside the page.
An attacker can steal cookies, user data, or control the session.
Using textContent ensures that the browser does not execute the input as code.
This simple change blocks most XSS attacks.
These examples show how dangerous XSS attacks can be and how easy they are to prevent.
By following safe output methods and sanitizing input, students gain the ability to build secure JavaScript applications that protect users and meet professional security standards.