Category menu with subcategories & shortcode

category-subcategory-menu.php

<?php

/**
 * Category menu with subcategories
 */

function bd_subategories_list($parent_cat_id = 100, $list_title = 'Category Name') { // category ID & name
?>
	<h3 class="widget-title"><?php echo $list_title ?></h3>
	<ul class="xoxo">
		<?php echo '<li><a href="' . get_category_link( $parent_cat_id ) . '">' . $list_title . '</a></li>'; ?>
		<ul class="xoxo">
			<?php
			wp_list_categories( array(
				'child_of' => $parent_cat_id,
				'title_li' => ''
			) );
			?>
		</ul>
	</ul>
<?php }

// Shortcode
function bd_subategories_list_shortcode() {

	return bd_subategories_list();
}
add_shortcode( 'subcategories-list', 'bd_subategories_list_shortcode' );