处理Asp.net Ajax框架12029,12007错误

<asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>

        <script language="javascript" type="text/javascript">
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
    function EndRequestHandler(sender, args)
    {
       
        if (args.get_error() != undefined)
        {
           if ((args.get_response().get_statusCode() == '12007') || (args.get_response().get_statusCode() == '12029'))
           {
                  
                  
                   document.writeln("服务器连接失败。");
                   window.onerror = false; //JS中遇到脚本错误时不做任何操作

            }
        }
    }
        </script>