Ajax使用示例

/***************************by
garcon1986********************************/
Index.php:
<script type="text/javascript" src="ajax.js" ></script>
<a href="#" onclick="funphp('S')" >S</a>
<a href="for.php?url=E" >E</a>
<div id="idiv"></div>
for.php:
<?php
error_reporting(E_ALL ^ E_NOTICE);
if($url = $_GET[url]){
for($i=1;$i<10;$i++){
echo $url;
}
exit();
}
?>
Ajax.js:
//首先声明变量
var xmlHttp;
//创建对象函数
function GetXmlHttpObject(){
try{
//Firefox, Opera, Safari
xmlHttp = new XMLHttpRequest();
}
catch(e){
try{
//MS IE 6.0+
xmlHttp = new ActiveXObject(Msxml2.XMLHTTP);
}
catch(e){
try{
//MS IS 5.5+
xmlHttp = new ActiveXObject(Microsoft.XMLHTTP);
}
catch(e){
alert("您的浏览器不支持AJAX！");
return false;
}
}
}
}
//发送请求函数
function funphp(t){
//调用GetXmlHttpObject函数
GetXmlHttpObject();
//open() 方法需要三个参数。第一个参数定义发送请求所使用的方法（GET 还是 POST）。第二个参数规定服务器端脚本的
URL。第三个方法规定应当对请求进行异步地处理。
xmlHttp.open("GET","for.php?url="+t, true);
//指定响应函数
xmlHttp.onreadystatechange = effect;
//发送请求。当使用GET方法时，一般send里的参数是null。如果是POST会有所不同。
xmlHttp.send(null);
}
//处理返回信息函数
function effect(){
if(xmlHttp.readyState == 4){
if(xmlHttp.status == 200){
var cao = xmlHttp.responseText;
document.getElementById('idiv').innerHTML = cao;
}
}
}
注释：
xmlHttpRequest.readyState的5种状态：
0 (Uninitialized)
The object has been created, but not initialized (the open method has
not been called).
1 (Open)
The object has been created, but the send method has not been called.
2 (Sent)
The send method has been called. responseText is not available.
responseBody is not available.
3 (Receiving)
Some data has been received. responseText is not available. responseBody
is not available.