function pw_load_scripts($hook) {
 
    global $pw_settings_page;
 
    if( $hook != $pw_settings_page ) 
        return;
 
    wp_enqueue_script( 'custom-js', plugins_url( 'js/custom.js' , dirname(__FILE__) ) );
}
add_action('admin_enqueue_scripts', 'pw_load_scripts');