In what scenarios would it be more efficient to use server-side PHP code to modify CSS classes for navigation links, rather than client-side JavaScript?

When the navigation links need to be dynamically modified based on server-side data or user authentication, it is more efficient to use server-side PHP code rather than client-side JavaScript. This ensures that the navigation links are accurately generated before being sent to the client, reducing the need for additional client-side processing.

<?php
// Sample PHP code to dynamically modify CSS classes for navigation links
$loggedIn = true; // Example variable indicating user authentication status

// Define CSS class based on user authentication status
$navClass = ($loggedIn) ? 'nav-link-authenticated' : 'nav-link';

// Output navigation link with dynamic CSS class
echo '<a href="#" class="' . $navClass . '">Home</a>';
?>