Actually, this is an ongoing problem. While Andy is right about the downloaded source, .val(...) and .attr('value',...) don't seem to actually modify the html. I think this is a javascript problem and not a jquery problem. If you had used firebug even you would have had the same question. While it seems that if you submit the form with the modified values it will go through, the html does not change. I ran into this issue trying to create a print preview of the modified form (doing [form].html()) it copies everything okay, including all changes except values changes. Thus, my modal print preview is somewhat useless... my workaround may have to be to 'build' a hidden form containing the values they have added, or generate the preview independently and make each modification the user makes also modify the preview. Both are inoptimal, but unless someone figures out why the value-setting behavior does not change the html (in the DOM i'm assuming) it will have to do.

简单地使用get和set下面的语法

GET

//Script 
var a = $("#selectIndex").val();

这里一个变量将保存hiddenfield(selectindex)的值

服务器端

<asp:HiddenField ID="selectIndex" runat="server" Value="0" />

SET

var a =10;
$("#selectIndex").val(a);

<javascript>


slots=''; hidden=''; basket = 0;

    cost_per_slot = $("#cost_per_slot").val();
    //cost_per_slot = parseFloat(cost_per_slot).toFixed(2)

    for (i=0; i< check_array.length; i++) {
        slots += check_array[i] + '\r\n';
        hidden += check_array[i].substring(0, 8) + '|';
        basket = (basket + parseFloat(cost_per_slot));
    }

    // Populate the Selected Slots section
    $("#selected_slots").html(slots);

    // Update hidden slots_booked form element with booked slots
    $("#slots_booked").val(hidden);     

    // Update basket total box
    basket = basket.toFixed(2);
    $("#total").html(basket);

我也有同样的问题，我找到了问题所在。我把HTML定义为

<form action="url" method="post">
    <input type="hidden" id="email" />
<form>
<script>
    function onsomeevent()
    {
       $("#email").val("a@a.com");
    }
</script>

在服务器上读取表单值总是导致电子邮件为空。在绞尽脑汁(和无数次搜索)之后，我意识到错误在于没有正确定义表单/输入。在修改输入时(如下所示)，它就像一个咒语一样有效

<input type="hidden" id="email" name="email" />

添加到这个线程，以防其他人有同样的问题。

.val没有为我工作，因为我抓取值属性服务器端和值并不总是更新。所以我用了:

var counter = 0;
$('a.myClickableLink').click(function(event){
   event.preventDefault();
   counter++;

   ...
   $('#myInput').attr('value', counter);
}

希望它能帮助到别人。

在尝试了一切之后，devtools显示他们改变了id，这是有效的:

$("#form-field-{field_id}").value('free');