TinyMCE button for WordPress shortcode

shortcodes.php

<?php

/**
 * Skeletal sample shortcode
 */
add_shortcode( 'pilau-sample', 'pilau_sample_shortcode' );
function pilau_sample_shortcode( $atts ) {
	extract( shortcode_atts( array(
		'text'	=> ''
	), $atts ) );
	return $text;
}

/**
 * Add TinyMCE buttons for shortcodes
 *
 * @link http://wp.smashingmagazine.com/2012/05/01/wordpress-shortcodes-complete-guide/
 * @link http://brettterpstra.com/adding-a-tinymce-button/
 */
add_action( 'init', 'pilau_tinymce_shortcode_buttons' );
add_filter( 'tiny_mce_version', 'pilau_refresh_tinymce' );
function pilau_tinymce_shortcode_buttons() {
	// Don't bother doing this stuff if the current user lacks permissions
	if ( ! current_user_can( 'edit_posts' ) && ! current_user_can( 'edit_pages' ) )
		return;
	// Add only in Rich Editor mode
	if ( get_user_option( 'rich_editing' ) == 'true' ) {
		add_filter( 'mce_external_plugins', 'pilau_tinymce_plugins' );
		add_filter( 'mce_buttons', 'pilau_register_tinymce_shortcode_buttons' );
	}
}
function pilau_register_tinymce_shortcode_buttons( $buttons ) {
	array_push( $buttons, "|", "pilau_sample" );
	return $buttons;
}
function pilau_tinymce_plugins( $plugin_array ) {
	$plugin_array['pilau_sample'] = get_template_directory_uri() . '/js/tinymce-buttons.js';
	return $plugin_array;
}
function pilau_refresh_tinymce( $ver ) {
	$ver += 3;
	return $ver;
}

tinymce-shortcode-buttons.js

/**
 * TinyMCE buttons for custom shortcodes
 */
( function() {
	tinymce.create( 'tinymce.plugins.PilauSample', {
		init: function( ed, url ) {
			ed.addButton( 'pilau-sample', {
				title: 'Insert Sample',
				image: url + '/img/tinymce-sample.png',
				onclick: function() {
					text = prompt( "Enter text", "" );
					ed.execCommand( 'mceInsertContent', false, '[pilau-sample text="' + text + '"]' );
				}
			});
		},
		createControl: function( n, cm ) { return null; },
	});
	tinymce.PluginManager.add( 'pilau-sample', tinymce.plugins.PilauSample );
})();