What are the potential security implications of relying solely on JavaScript for form validation in PHP applications?

Relying solely on JavaScript for form validation in PHP applications can lead to security vulnerabilities as client-side validation can be bypassed by users with malicious intent. To ensure secure form validation, it is essential to perform server-side validation in addition to client-side validation.

// Server-side form validation example
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST["name"];
    $email = $_POST["email"];
    
    if (empty($name) || empty($email)) {
        echo "Please fill out all required fields.";
    } else {
        // Process form data
    }
}