Gets a list of Woocommerce categories that have featured products and outputs them

featured_by_category.php

				<?php
					$types = get_terms( array(
						'taxonomy'			=> 'product_cat',
						'hide_empty'		=> true,
						'field'				=> 'slug'
					));
					foreach($types as $type) {
						$args = array(
							'post_type'			=> 'product',
							'tax_query'			=> array(
								array(
									'taxonomy'	=> 'product_cat',
									'field'		=> 'slug',
									'terms'		=> $type->name,
								),
								'relation' => 'AND',
								array(
									'taxonomy'	=> 'product_visibility',
									'field'		=> 'name',
									'terms'		=> 'featured',
								)
							)
						);
						$loop = new WP_Query($args);
						if($loop->have_posts()) :
				?>
        <h2><?php echo $type->name; ?></h2><!-- category title -->
				<?php
						while ($loop->have_posts()) : $loop->the_post();
        ?>
        <!-- loop stuff -->
        <?php
						endwhile;
						wp_reset_postdata();
						endif;
					}
				?>