在ASP.net Ajax中防止用戶多次提交

   var btnSubmit = "<%=btnSubmit.ClientID %>";
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    prm.add_initializeRequest(onInitializeRequest);
  
    
   function onInitializeRequest(sender,args)
    ...{
        if(prm.get_isInAsyncPostBack()&&args.get_postBackElement().id == btnSubmit)
       ...{
            args.set_cancel(true);
            //給用戶提示正在處理中
       }
       $get(btnSubmit).disabled = true;
    }

 PS: btnSubmit爲頁面提交按鈕