<!DOCTYPE html>
<html lang="en">
<head>
<Meta charset="utf-8">
<script type="text/javascript">
function $(id){
return document.getElementById(id);
}
var xmlhttp="";
function get_xmlhttp(){
xmlhttp=new XMLHttpRequest();
var url='/ajax/test.PHP';
var data='username='+$('name').value;
xmlhttp.open('post',url,true);//打开请求
xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded;");
xmlhttp.onreadystatechange=callback;//指定回调函数
xmlhttp.send(data);//发送数据,若get填null；若post，则填实际数据
}
function callback(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
var obj=xmlhttp.responseText;
obj=eval("("+obj+")");
document.getElementById('msg').value=obj.res;
}
}
</script>
</head>
<body>
<div id="container">
<div id="body">
<form action="#" method="post">
username:<input type="text" id="name" onKeyUp="get_xmlhttp();"/>
password:<input type="password" id="pwd"/>
<input type="submit" value="确定" onClick="get_xmlhttp();"/>
<input type="text" id="msg"/>
</form>
</div>
</body>
</html>
原文链接：https://www.f2er.com/ajax/162351.html