What are the potential security risks associated with using JavaScript to close web pages in PHP?

Using JavaScript to close web pages in PHP can introduce security risks such as cross-site scripting (XSS) attacks if the JavaScript code is not properly sanitized. To mitigate this risk, it is important to validate and sanitize any user input before using it to generate JavaScript code.

// Sanitize user input before using it in JavaScript code
$user_input = htmlspecialchars($_POST['user_input']);

// Output sanitized user input in JavaScript code to close the web page
echo "<script> window.close(); </script>";