回調函數實例

var xmlHttpRequest;

function fnquery(){

var cypz = '${cpcyModel.cypz}';

var ajx = 'true';

xmlHttpRequest = new XMLHttpRequest(); 

        xmlHttpRequest.onreadystatechange = callback; 

        xmlHttpRequest.open("GET", "<%=webapp%>/cpcy/cpcyAction!list.dhtml?firstFlag=clear&ajax="+ajx, true);

        xmlHttpRequest.send(null);  

}

//回調函數 

   function callback() { 

   alert(xmlHttpRequest.readyState);

       //alert(xmlHttpRequest.readyState); 

       //5。接收響應數據 

       //判斷對象的狀態是交互完成 

       if (xmlHttpRequest.readyState == 4) { 

           //判斷http的交互是否成功 

           if (xmlHttpRequest.status == 200) { 

               //獲取服務器器端返回的數據 

               //獲取服務器段輸出的純文本數據 

              var responseText = xmlHttpRequest.responseText; 

               alert(responseText);

          if("true" == responseText) {

         

$("#form1").attr('action','cpcyAction!enterlist.dhtml');

$("#form1").attr('method','post');

$("#form1").submit();

}

           } else { 

               alert("出錯了！！！"); 

           } 

       } 

   }