[WordPress] add select2 to wp-admin panel

// Ajouter select2 à l'admin
function enqueue_select2_jquery() {
    wp_register_style('select2css', '//cdnjs.cloudflare.com/ajax/libs/select2/3.4.8/select2.css', false, '1.0', 'all');
    wp_register_script('select2', '//cdnjs.cloudflare.com/ajax/libs/select2/3.4.8/select2.js', array('jquery'), '1.0', true);
    wp_enqueue_style('select2css');
    wp_enqueue_script('select2');
}
add_action('admin_enqueue_scripts', 'enqueue_select2_jquery');
function custom_admin_js_css() {
    echo '<script>
            jQuery(document).ready(function($) {
                $(\'[name="post_author_override"]\').select2();
            });
        </script>
        <style>
            .select2-container {
                width:100%;
            }
        </style>';
}
add_action('admin_footer', 'custom_admin_js_css');