What are the potential security risks associated with using JavaScript in PHP applications?

Potential security risks associated with using JavaScript in PHP applications include Cross-Site Scripting (XSS) attacks, where malicious scripts are injected into web pages to steal sensitive information or perform unauthorized actions. To mitigate this risk, it is important to properly sanitize and validate user input before using it in JavaScript code to prevent XSS vulnerabilities.

// Sanitize and validate user input before using it in JavaScript code
$user_input = $_POST['user_input'];

// Sanitize user input to prevent XSS attacks
$clean_input = htmlspecialchars($user_input, ENT_QUOTES, 'UTF-8');

// Use the sanitized input in JavaScript code
echo "<script> var userInput = '" . $clean_input . "'; </script>";