ajax技术始终出去发送状态

ajaxphp

if($id=$_GET[id]){
  for($i=1;$i<=5;$i++){echo $i;
//sleep(2);
   }
   exit();
}
<html>
<head>
<title> </title>
<script type="text/javascript" src='jquery-1.4.2.min.js'></script></head>
<script type="text/javascript">
var xmlHttp;
function S_xmlhttprequest(){
if(window.ActiveXObject){
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp=new XMLHttpRequest();
}
}
function funphp100(url){
S_xmlhttprequest();
xmlHttp.open("GET","test.php?id="+url,true);
xmlHttp.onreadystatechange=byphp;
xmlHttp.send(null);
}
function byphp(){
if(xmlHttp.readyState==1){
document.getElementById('php100').innerHTML="loading....";
}
if(xmlHttp.readyState==4){ var byphp100 = xmlHttp.responseText;
document.getElementById('php100').innerHTML=byphp100; } }</script>
<body>
<a href= "#" onclick="funphp100('o')">o</a>
<a href= "#" onclick="funphp100('t')">t</a>
<a href= "#" onclick="funphp100('x')">x</a>
<br>
<div id="php100"></div>
</body>
</html>
else if(widow.XMLHttpRequest){
       xmlHttp=new XMLHttpRequest();
    }
window

ajax技术 始终出去发送状态