WooCommerce - Create a product categories dropdown list in a shortcode

gistfile1.php

<?php

/**
 * WooCommerce Extra Feature
 * --------------------------
 *
 * Register a shortcode that creates a product categories dropdown list
 *
 * Use: [product_categories_dropdown orderby="title" count="0" hierarchical="0"]
 *
 */
add_shortcode( 'product_categories_dropdown', 'woo_product_categories_dropdown' );

function woo_product_categories_dropdown( $atts ) {

  extract(shortcode_atts(array(
  	/* changing count to show_count for removing the warnings on the page */
    'show_count'         => '0',
    'hierarchical'  => '0',
    'orderby' 	    => ''
    ), $atts));
	
	ob_start();
	
	$c = $count;
	$h = $hierarchical;
	$o = ( isset( $orderby ) && $orderby != '' ) ? $orderby : 'order';
		
	// Stuck with this until a fix for http://core.trac.wordpress.org/ticket/13258
	woocommerce_product_dropdown_categories( $c, $h, 0, $o );

	?>
	<script type='text/javascript'>
	/* <![CDATA[ */
		var product_cat_dropdown = document.getElementById("dropdown_product_cat");
		function onProductCatChange() {
			if ( product_cat_dropdown.options[product_cat_dropdown.selectedIndex].value !=='' ) {
				location.href = "<?php echo home_url(); ?>/?product_cat="+product_cat_dropdown.options[product_cat_dropdown.selectedIndex].value;
			}
		}
		product_cat_dropdown.onchange = onProductCatChange;
	/* ]]> */
	</script>
	<?php
	
	return ob_get_clean();
	
}