asp.net里面的javascript没有设置隐藏字段值

Question

我是Asp.net的新手。我试图使用GeoLocation获取纬度和经度，并尝试将值设置为PageLoad上的隐藏字段。

问题是隐藏字段的值始终为空。但是请在javascript调用中查看alert语句，警报会正确显示纬度和经度值。如何填充C＃代码中的隐藏字段，以便在页面加载时将这些值作为电子邮件发送。请帮忙

aspx代码：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <script>
       window.onload = getLocation();
       var x = document.getElementById("demo");
       function getLocation() {
           if (navigator.geolocation) {
               navigator.geolocation.getCurrentPosition(showPosition);
           }
           else { x.innerHTML = "Geolocation is not supported by this browser."; }
       }
        function showPosition(position) {
            document.getElementById('<%=Latitide.ClientID%>').value = position.coords.latitude;
            document.getElementById('<%=Longitude.ClientID%>').value = position.coords.longitude;
           alert("Latitude: " + position.coords.latitude +
               "<br>Longitude: " + position.coords.longitude);

       }

        </script>
</head>
<body>
    <form id="form1" runat="server">

    <br />
   <asp:HiddenField runat="server" ID="Latitide" ClientIDMode="Static" Value="" />
   <asp:HiddenField runat="server" ID="Longitude" ClientIDMode="Static" Value="" />
    </form>
</body>
</html>

代码背后：

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

        Response.Write("Latitude " + Latitide.Value + "-Longitude" + Request.Form["Longitude"]);
    }


}