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

<!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>Kontrolka HiddenField</title>
</head>

<script language=javascript>
   function ChangeHiddenValue()
   {
      alert('Wprowadzanie ChangeHiddenValue');

      var hdnId = '<%=hdnSecretValue.ClientID%>'
      var hdn = document.getElementById(hdnId);

      var txt = document.getElementById('txtSecretValue');

      hdn.value = txt.value;
      alert('Warto zostaa zmieniona');
   }
</script>

<body>
   <form id="form1" runat="server">
   <div>
      <h1>Kontrolka HiddenField</h1>
      <h2>Strona zostaa odwieona o <% =DateTime.Now.ToString() %>.</h2>
      <asp:HiddenField ID="hdnSecretValue" runat="server"
         OnValueChanged="hdnSecretValue_ValueChanged" />
      Wprowad tajn warto:
      <asp:TextBox ID="txtSecretValue" runat="server" />
      <br />
      <br />
      <input type=button value="Zmiana ukrytej wartoci"
         onclick="ChangeHiddenValue()" />
      <asp:Button ID="btnPost" runat="server" Text="Odwie" />
      <br />
      <br />
      <asp:Label ID="lblMessage" runat="server" Text=""/>
   </div>
   </form>
</body>
</html>
