值改变后触发后台代码 HTML文本框的值改变后触发后台代码的方法

onfocus="WdatePicker({maxDate:'%y-%M-%d',isShowClear:false,readOnly:true})"
                        onpropertychange="showValue(this.value)" ></asp:TextBox>

日
                    <asp:HiddenField ID="hiddenDate" runat="server"

OnValueChanged="hiddenDate_ValueChanged"
                        EnableViewState="false" />
 <div style="display: none;">
                        <asp:ImageButton ID="btnHid" runat="server"

ImageUrl="~/Resource/images/Btn_Find.gif"
                            CausesValidation="false" align="absmiddle"

OnClick="btnHid_Click" />
                    </div>

        //格式化当前“月”，“日”格式。
        if ((today.getMonth() + 1) < 10) {
            todayMonth = "0" + (today.getMonth() + 1);
        }
        if (today.getDate() < 10) {
            todayDate = "0" + today.getDate();
        }

        //获得当前的日期。
        var oldValue = //www.qb5200.com/Health/archive/2012/02/10/today.getFullYear() +"-" + todayMonth + "-" + todayDate;

        function showValue(obj) {
            //当查询日期不为空时，就触发查询按钮。
            if (obj != "" && obj != oldValue) {
                oldValue = //www.qb5200.com/Health/archive/2012/02/10/obj;
                $('#txtName').get(0).select();
                $("#hiddenDate").val(obj);
                $('#btnHid').trigger("click");
                return false;
            }
        }
    </script>

    //根据用户选择的时间查询。
    protected void btnHid_Click(object sender, ImageClickEventArgs e)
    {
        //后台代码
    }