如何从后端asp.net上的文本框中获取新值

Question

我想点击保存按钮时从文本框控件中获取文本。

    <tr id="comsec2_2">

                    <td style="font-size: 12px; width: 109px;">Comments:<img class="popup2" id="popup_2_2" src="magnifier-left.png" alt="" /></td>
                    <td>
                        <asp:TextBox ID="TXT_Comments_Section2_2" ClientIDMode="Static" runat="server" Width="500px" Height="50px" TextMode="MultiLine"></asp:TextBox>
                    </td>

                </tr>

当img tapped对话框打开以添加新评论时。保存按钮保存TXT_Comments_Section2_2旧评论和新评论。

 function ShowDialog2(id) {
        console.log(id);
        var tt2 = "";
        if (id == "2_2") tt2 = $("#TXT_Comments_Section2_2").val();


        $('#ROlbl1234').html(tt2);
        $('#lbl1234').html("");
        $("#dialog2").dialog({
            height: 600,
            width: 800,
            modal: true,
            buttons: {
                'Save': function () {
                    if (id == "2_2") document.getElementById('TXT_Comments_Section2_2').value = $("#lbl1234").val() + "\n" + $("#ROlbl1234").val();

                    $("#dialog2").dialog("close");
                }
            },
        });
    }

当我点击完成按钮并尝试获取文本

Protected Sub BTN_Save_Total2_Click(sender As Object, e As EventArgs) Handles BTN_Save_Total2.Click
Steps = TXT_Steps.Text
BTN_Save_Total2.Enabled = False
Dim Web As SPWeb = SPContext.Current.Web
Dim List As SPList = Web.Lists("ConsultancyForm")

    'Update list items
    If (hiddenCurrentItemId.Value = String.Empty) Then
        Dim UpdateItem As SPListItem = List.Items.Add()

        UpdateItem("Comments") = vbCrLf & vbCrLf & "----" & now.ToString(format) & "----" & vbCrLf & TXT_Comments_Section2_2.Text

        UpdateItem.Update()
....

控件没有新值。当我从控制台调用.val（）时，我获得了新的价值。