原生态的Ajax写法

<script language="javascript" type="text/javascript">
     var request = false;
     try {
       request = new XMLHttpRequest();  // 在IE7及非IE浏览器中可以用
     } catch (trymicrosoft) {
       try {
         request = new ActiveXObject("Msxml2.XMLHTTP"); //在较新的IE版本
       } catch (othermicrosoft) {
         try {
           request = new ActiveXObject("Microsoft.XMLHTTP"); // 在IE7 以前的版本中可以用
         } catch (Failed) {
           request = false;
         }   
       }
     }
     if (!request)
       alert("Error initializing XMLHttpRequest!");


     function getCustomerInfo() {
       var phone = document.getElementById("phone").value;   //获取请求参数
       var url = "/cgi-local/lookupCustomer.PHP?phone=" + escape(phone);  //拼接URL
      xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");   //  规定编码  用post方式请求 一定要加
      xmlhttp.setRequestHeader("Content-length",params.length); // 可设可不设   规定长度
       request.open("GET",url,true);  //选择请求方式 获取数据
       request.onreadystatechange = updatePage;  调用回调函数
       request.send(null);//里面是参数 例如：request.send(“ajax=1&b=2”);
     }

//回调函数
  function updatePage() {
     if (request.readyState == 4) {
       if (request.status == 200) {
         var response = request.responseText.split("|");
         document.getElementById("order").value = response[0];
         document.getElementById("address").innerHTML =
         response[1].replace(/\n/g,"");
       } else
         alert("status is " + request.status);
     }
   }


</script>