如何使用jQuery确定表行是第一行还是最后一行

您可以尝试在tr上使用prevAll()和nextAll()。如果没有返回结果,则表示所述tr是第一个子或最后一个子。

$(".up,.down").click(function(){
    var row = $(this).parents("tr:first");
    if ($(this).is(".up")) {
        row.insertBefore(row.prev());
        if(row.prevAll().length == 0){
           //you just moved a row to the top. this is where you disable the button
           row.find('.up').find('input').attr('disabled','true');
           //the row that was the top before had its up disabled, enable it
           row.prev().find('.up').find('input').removeAttr('disabled');
        } 
    } else {
        row.insertAfter(row.next());
        //do same kind of thing here with nextAll
    }
});