WooCommerce - Adds stock status to the dropdown on product pages

dropdown-stock-status.php

<?php 

add_action( 'woocommerce_after_add_to_cart_form', 'dropdown_waitlist_label' );

function dropdown_waitlist_label() {
	echo "
		<script>
		jQuery(document).ready(function($) {
			var variation_data = $('form.variations_form').attr('data-product_variations');
			var variation_data = JSON.parse(variation_data);
			$('#pa_size > option').each(function() {
				for (var i = 0; i < variation_data.length; i++) {
					var variation = variation_data[i];
					if ($(this).val() == variation.attributes.attribute_pa_size) {
						if ( false == variation.is_in_stock ) {
							$(this).text( variation.attributes.attribute_pa_size + '\u00A0\u00A0\u00A0–\u00A0\u00A0\u00A0\u00A0Out of Stock');
						}
						if ( variation.min_qty == 1 && variation.max_qty == 1 ) {
							$(this).text( variation.attributes.attribute_pa_size + '\u00A0\u00A0\u00A0–\u00A0\u00A0\u00A0\u00A01 left in stock' );
						}
					}
				}
			});
		});
	</script>";
}