@CharlieJustUs在使用Fiddle时会自动为您设置$变量。当脚本尝试在站点上运行时，该变量未设置，并且失败。

请试试这个。

jQuery(document).ready(function($) {
    $(function() {
        $(\'ul.clearfix\').each(function() {
            var $select = $(\'<select class="dropdown-toggle" />\');
            $(this).find(\'a\').each(function() {
                var $option = $(\'<option />\');
                $option.attr(\'value\', $(this).attr(\'href\')).html($(this).html());
                $select.append($option);
            });
            $(this).replaceWith($select);
        });
    });

    // This will grab the value the select is being set to and redirect to the link
    $(\'select.dropdown-toggle\').on(\'change\', function(){
       window.location.href = $( this ).val();
    });
});