Как сделать AJAX-подгрузку подкатегорий в модуле mod_virtuemart_category? - Joomla 3.x: Общие вопросы

<div class="calc-wrapper">

<select>
<?php foreach ($categories as $category) {
	$active_menu = '';
	$caturl = JRoute::_('index.php?option=com_virtuemart&view=category&virtuemart_category_id='.$category->virtuemart_category_id);
	$cattext = $category->category_name;
	if (in_array( $category->virtuemart_category_id, $parentCategories)) {
		$active_menu = 'class="active"';
	} ?>
	<option <?php echo $active_menu ?> alt="<?php echo $caturl; ?>">
			<?php echo $cattext ?>
	</option>
	
	<?php
} ?>
</select>


<select>
<?php foreach ($categories as $category) { ?>

		<?php if (!empty($category->childs)) { ?>
		
			<?php
				foreach ($category->childs as $child) {
					$caturl = JRoute::_('index.php?option=com_virtuemart&view=category&virtuemart_category_id='.$child->virtuemart_category_id);
					$cattext = vmText::_($child->category_name);
			?>
			<option>
				<?php echo $cattext; ?>
			</option>
			<?php } ?>
		
		<?php } ?>
	<?php
} ?>
</select>
</div>