<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>JS</title>
<style>
#box{
width:600px;
height:200px;
padding:20px;
border:1px solid #999;
}
</style>
</head>
<body>
<h1>ajax</h1>
<hr>
<button onclick="loadHtml()">加载</button>
<div id="box"></div>
<script>
function loadHtml(){
// ①实例化 XMLHttpRequest对象
if (window.XMLHttpRequest) {
//非IE IE7+
var xhr = new XMLHttpRequest();
} else {
//IE 6
var xhr = new ActiveXObject(‘Microsoft.XMLHTTP‘);
}
//② 给xhr 绑定事件， 检测请求的过程
xhr.onreadystatechange = function(){
console.log(xhr.readyState);
//如果成功介绍到响应
if (xhr.status == 200 && xhr.readyState == 4) {
document.getElementById(‘box‘).innerHTML = xhr.responseText;
}
}
//③ 进行请求的初始化
xhr.open(‘get‘, ‘http://localhost/s32/JS10_Jquery01/lessson/1.php‘, true);
//④ 正式发送请求
xhr.send();
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/shanyansheng/p/5060817.html