<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptManager1" runat="server" ScriptMode="Debug">
</asp:ScriptManager>
<div>
<asp:contentplaceholder id="ContentPlaceHolder1" runat="server">
</asp:contentplaceholder>
</div>
<br />
<div id="message" style="color:Red;"></div>
<script language="javascript" type="text/javascript">
var timeoutSeed = null;
function showMessage(message, timeout)
{
$get("message").innerHTML = message;
if (timeoutSeed)
{
window.clearTimeout(timeoutSeed);
}
timeoutSeed = window.setTimeout(
function(){ $get("message").innerHTML = ""; },
timeout 2500);
}
</script>
</form>
1_PrecedencePostBack.aspx
<%@ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="1_PrecedencePostBack.aspx.cs" Inherits="_1_PrecedencePostBack" Title="PrecedencePostBack" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="0" DynamicLayout="false">
<ProgressTemplate>
<span style="color:Red">Loading...</span>
</ProgressTemplate>
</asp:UpdateProgress>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<%= DateTime.Now %><br />
<asp:Label ID="Label1" runat="server" Text=""></asp:Label><br />
<asp:Button ID="btnPrecedence" runat="server" Text="Precedence" OnClick="Button_OnClick" />
<asp:Button ID="btnNormal" runat="server" Text="Normal" OnClick="Button_OnClick" />
</ContentTemplate>
</asp:UpdatePanel>
<script type="text/javascript" language="javascript">
var lastPostBackButtonId = null;
var btnPrecedenceId = "<%= this.btnPrecedence.ClientID %>";
Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(
function(sender, e)
{
var prm = Sys.WebForms.PageRequestManager.getInstance();
if (prm.get_isInAsyncPostBack())
{
if (lastPostBackButtonId == btnPrecedenceId)
{
e.set_cancel(true);
if (e.get_postBackElement().id == btnPrecedenceId)
{
showMessage("you cannot click btnPrecedence more than once.");
}
else
{
showMessage("please wait for the btnPrecedence to finish.");
}
return;
}
else if (e.get_postBackElement().id == btnPrecedenceId)
{
showMessage("you've clicked the btnPrecedence button, the btnNormal request will be cancelled.");
}
else
{
showMessage("you've clicked the btnNormal button more than once, only the last request will be processed.");
}
}
lastPostBackButtonId = e.get_postBackElement().id;
});
</script>
</asp:Content>
1_PrecedencePostBack.aspx
using System;
using System.Data;
using System.Configuration;
using System.Collections;
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;
using System.Threading;
public partial class _1_PrecedencePostBack : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button_OnClick(object sender, EventArgs e)
{
Thread.Sleep(3000);
Button button = sender as Button;
this.Label1.Text = String.Format("you've clicked ''{0}'' button", button.Text);
}
}
This code uses initializeRequest event to disallow user to click button more than once, or based on the priority to determine which button's request should be processed.
