ASP.NET Tutorial/HTML Controls/Hidden
Hidden field
<source lang="csharp">
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default_aspx" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">
<title>HiddenField Control</title>
</head> <script language=javascript>
function ChangeHiddenValue() { alert("Entering ChangeHiddenValue"); var hdnId = "<%=hdnSecretValue.ClientID%>" var hdn = document.getElementById(hdnId); var txt = document.getElementById("txtSecretValue"); hdn.value = txt.value; alert("Value changed"); }
</script> <body>
<form id="form1" runat="server">
HiddenField Control
This page was posted at <% =DateTime.Now.ToString() %>.
<asp:HiddenField ID="hdnSecretValue" runat="server" OnValueChanged="hdnSecretValue_ValueChanged" /> Enter secret value: <asp:TextBox ID="txtSecretValue" runat="server" />
<input type=button value="Change hidden value" onclick="ChangeHiddenValue()" /> <asp:Button ID="btnPost" runat="server" Text="Post" />
<asp:Label ID="lblMessage" runat="server" Text=""/>
</form>
</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class Default_aspx : System.Web.UI.Page {
protected void hdnSecretValue_ValueChanged(object sender, EventArgs e) { HiddenField hdn = (HiddenField)sender; lblMessage.Text = "The new value is " + hdn.Value + "."; } }</source>