Why won't WordPress load thickbox and media-upload scripts?

Question

I'm working on a plugin that uses thickbox and media-upload to set some images. Neither will load using this code:

  function add_my_files() {
        echo 'happy happy happy';
        wp_register_style( 'adminstyles', plugins_url('/css/slider.css', __FILE__));
        wp_enqueue_style( 'adminstyles' );
        wp_enqueue_style('thickbox');

        wp_enqueue_script('media-upload');
        wp_enqueue_script('thickbox');

        wp_register_script('hdjs',plugins_url('/js/slider.js', __FILE__),array('media-upload','thickbox'),'',true);
        wp_enqueue_script('hdjs');
    }

add_action( 'admin_init', 'add_my_files' );

my css and js files load but not thickbox and media-upload.

Thanks

Answer 1

The correct hook to include your asset files in WP is admin_enqueue_scripts:

NOTE: I recommend you too use get_current_screen (see is_my_admin_screen() definition below) to just include your js/css files when you actually needed.

add_action('admin_enqueue_scripts', 'add_my_files');

function add_my_files()
{
    /*
     * a good WP citizen only loads
     * their javascript/css where it is needed
     */
    if ( ! is_my_admin_screen()) // defined below
        return;

    wp_register_style('adminstyles', plugins_url('/css/slider.css', __FILE__));
    wp_enqueue_style('adminstyles');
    wp_enqueue_style('thickbox');

    wp_enqueue_script('media-upload');
    wp_enqueue_script('thickbox');

    wp_register_script('hdjs', plugins_url('/js/slider.js', __FILE__), array('media-upload', 'thickbox'), '', true);
    wp_enqueue_script('hdjs');
}

function is_my_admin_screen()
{
    $screen = get_current_screen();

    if (is_object($screen) && $screen->id == 'my_plugin_page_id') // var_dump($screen->id); find your own id
        return true;
    else
        return false;
}

ref: http://codex.wordpress.org/Plugin_API/Action_Reference/admin_enqueue_scripts ref: http://codex.wordpress.org/Function_Reference/get_current_screen

---

Besides hopefully you are using a class to wrap all your plugin or you will have worse problems than this.

Please feedback. I am very interested in this issue because WP plugins puts food and beers on my table.