javaScript（ajax）（一）—— xmlhttp.onreadystatechange 执行顺序
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<script type="text/javascript" src="<%=request.getContextPath() %>/jQuery/jquery-1.8.3.js"></script>
<script language="javascript">
function js_ajax(){
var xmlhttp;
if( window.XMLHttpRequest ){
xmlhttp = new XMLHttpRequest();
alert("IE6以上");
}else{
xmlhttp = new ActiveXObject( "Microsoft.XMLHTTP" );
alert("IE5或IE6");
}
xmlhttp.onreadystatechange = function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
document.getElementById("jQuery_div").innerText = xmlhttp.responseText;
}
}
xmlhttp.open("GET","<%=request.getContextPath()%>/TestServlet?name=jQuery",true);
xmlhttp.send();
alert("xmlhttp.readyState:"+xmlhttp.readyState+"***xmlhttp.status:"+xmlhttp.status);
/* xmlhttp.onreadystatechange = run();
function run(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
document.getElementById("jQuery_div").innerText=xmlhttp.responseText;
}
} */
/* xmlhttp.onreadystatechange = function(){ 这段代码放在这不能执行？
if (xmlhttp.readyState==4 && xmlhttp.status==200){
document.getElementById("jQuery_div").innerText=xmlhttp.responseText;
}
} */
}
</script>
<body>
<form name="form" id="form" action="" method="post">
<input type="button" onClick="js_ajax()" value="javascript_ajax">
<div id="jQuery_div" ></div>
</form>
</body>
</html>
