步骤1：将以下代码添加到变量中。php文件位于woocommerce插件中（单个产品/添加到购物车）

<?php
    $product_variations = $product->get_available_variations();

    echo \'<ul class="attr_avail_custom dnone">\';
    foreach ($product_variations as $variation)  {
        $var_data = $variation[\'attributes\'];

        if(!$variation[\'is_in_stock\']) {
            echo \'<li>\';
            foreach ($var_data as $vk => $vv) {

                echo "<span data-key=$vk data-value=$vv >$vv</span>";
            }
            echo \'</li>\';
        }

    }
    echo \'</ul>\';
?>

    //SOLD OUT text jquery for Prdocut detailed pages...
    if( jQuery(\'ul.attr_avail_custom\').length > 0 ) { /*loading jQuery only if the current page is product\'s detail page*/

        //On hovering mouse over the SIZE dropdown - adding SOLD OUT text according to the hidden \'out of stock\' attributes available in \'ul.attr_avail_custom\'...
        jQuery(\'select[id*="size"]\').hover(function () {
            var selected_color = jQuery(\'select[id*="colour"]\').val();

            //firslty removing SOLD OUT from all if added previously...
            jQuery(\'select[id*="size"] option:not([value=""])\').each(function () {
                jQuery(this).text(jQuery(this).val());
            });

            /*checking if the selected colour is in the SOLD OUT pair printed (above select boxes) in hidden and coded in this file woocommerce (single-product\\add-to-cart\\variable.php) */
            jQuery(\'ul.attr_avail_custom [data-key*="colour"][data-value="\' + selected_color + \'"]\').each(function () { /*out of stock size loop fro selected colour*/
                var out_stock_colour_val = jQuery(this).data(\'value\');
                var out_stock_size_val = jQuery(this).parent().find(\'[data-key*="size"]\').data(\'value\');

                //Finally adding SOLD OUT text...
                jQuery(\'select[id*="size"] option[value="\' + out_stock_size_val + \'"]\').text(out_stock_size_val + \' - SOLD OUT\');

            });
        });

        //if mouse is hover over COLOUR dropdown - we must have to (1) Flush the SIZE if seleceted and (2) Triggering clicks on both Dropdowns to prevent AJAX conflicts... (this is required)
        jQuery(\'select[id*="colour"]\').hover(function () {
            //Flushing selecrted SIZE and triggering click..
            jQuery(\'select[id*="size"]\').trigger(\'click\');

            jQuery(\'select[id*="size"] option:eq(0)\').attr(\'selected\',\'selected\');

            //triggering click on COLOUR dropdown..
            jQuery(\'select[id*="colour"]\').trigger(\'click\');

        });
    }