Customizer enqueue 2

function mytheme_customizer_preview_js() {
   wp_enqueue_script( 'mytheme_customizer_preview', get_template_directory_uri() . '/js/customizer.js', array( 'customize-preview' ), '20160321', true );
   wp_localize_script( 'mytheme_customizer_preview', 'mythemeLocalizer', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ), ) );
}
add_action( 'customize_preview_init', 'mytheme_customizer_preview_js' );