Add "Low Stock" badge to WooCommerce catalog products

low-stock.php

<?php

/**
 * Add low stock badge.
 */
function iconic_add_low_stock_badge() {
	global $product;

	$manage_stock = $product->get_manage_stock();
	$stock = $product->get_stock_quantity();

	if ( ! $manage_stock || $stock > 10 ) {
		return;
	}
	?>
	<span class="iconic-badge iconic-badge--low-stock"><?php _e( 'Low Stock', 'iconic' ); ?></span>
	<?php
}

add_action( 'woocommerce_before_shop_loop_item', 'iconic_add_low_stock_badge', 10 );