How can developers ensure smooth functioning of PHP-based websites after updating templates and CMS platforms like Joomla?

To ensure smooth functioning of PHP-based websites after updating templates and CMS platforms like Joomla, developers should thoroughly test the updated templates and CMS platforms in a staging environment before deploying them to the live website. They should also review and update any custom PHP code to ensure compatibility with the new templates and CMS version. Additionally, developers should keep track of any deprecated functions or features in the updated templates and CMS platforms and make necessary changes to their code accordingly.

// Example code snippet for updating custom PHP code to ensure compatibility with updated templates and CMS platforms

// Check if a deprecated function is being used
if (function_exists('deprecated_function')) {
    // Update the code to use the new function
    $new_function_result = new_function();
} else {
    // Keep using the old function
    $deprecated_function_result = deprecated_function();
}