initializerequest.aspx

ajax实例,可以了解ajax的原理

<%@ Page Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="InitializeRequest.aspx.cs"
    Inherits="ClientScripting_SysWebForms_InitializeRequest" Title="InitializeRequest" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">

    <script runat="Server">
        protected void Button1_Click(object sender, EventArgs e)
        {
            System.Threading.Thread.Sleep(3000);
        }
    </script>

    <asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="0" DynamicLayout="false">
        <ProgressTemplate>
            Loading...
        </ProgressTemplate>
    </asp:UpdateProgress>
    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            <%= DateTime.Now %>
            <br />
            <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
            &nbsp;&nbsp;
            <asp:Button ID="Button2" runat="server" Text="cancel属性测试" OnClick="Button1_Click" />
        </ContentTemplate>
    </asp:UpdatePanel>
    <p>
        <textarea id="TraceConsole" style="width: 500px; height: 300px;"></textarea>
    </p>

    <script type="text/javascript" language="javascript">
	
	    Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(initializeRequestHandler);
	    
		function initializeRequestHandler(sender, e)
		{
		    // postBackElement - 产生回发事件的元素
		    if (e.get_postBackElement().id == "<%= Button2.ClientID %>")
		    {
		        // InitializeRequestEventArgs继承自Sys.CancelEventArgs 
		        // 取消回发
		        e.set_cancel(true);
		    }
		    else
		    {
		        // 获得页面的PageRequestManager类的实例
				var prm = Sys.WebForms.PageRequestManager.getInstance();
			
			    Sys.Debug.trace(e.get_postBackElement().id);
    			
    			// Sys.WebForms.PageRequestManager的isInAsyncPostBack属性 - 是否正在异步回发过程中
			    Sys.Debug.trace(prm.get_isInAsyncPostBack());
		    }
		}
    </script>

</asp:Content>