Concepts and examples of javascript's ajax functionality
AJAX即“Asynchronous Javascript And XML”（异步JavaScript和XML）。
个人理解：ajax就是无刷新提交，然后得到返回内容。
对应的不使用ajax时的传统网页如果需要更新内容（或用php做处理时），必须重载整个网页页面。
示例：
html代码如下
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Ajax示例</title>
<style>
#loginForm {
border-collapse: collapse;
}
#loginForm,#loginForm td {
border:#550 1px solid;
text-align:center;
}
</style>
</head>
<body>
<table id="loginForm">
<tr>
<td>用户名：</td>
<td><input type="text" id="userName"/></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="password" id="password"/></td>
</tr>
<tr>
<td colspan=2><input id="submitBtn" type="submit" value="ajax提交"/></td>
</tr>
</table>
<script type="text/javascript" language="javascript">
document.getElementById('submitBtn').addEventListener('click', clickSubmit);
function clickSubmit() {
makeRequest('./test.php');
}
var req = false;
/**
* 创建ajax请求
* url 处理请求的php位置
*/
function makeRequest(url) {
req = false;
//创建一个XMLHTPP实例
if (window.XMLHttpRequest) { // ie9以上和w3c浏览器的对象
req = new XMLHttpRequest();
if (req.overrideMimeType) {
//如果服务器的响应没有XML mime-type header,某些Mozilla浏览器可能无法正常工作.
//为了解决这个问题, 如果服务器响应的header不是text/xml,可以调用其它方法修改该header.
req.overrideMimeType('text/xml');
}
} else if (window.ActiveXObject) { // IE678专用
try {
req = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
alert('new window.ActiveXObject() failed!');
}
}
if (!req) {
alert('Giving up :( Cannot create an XMLHTTP instance');
return false;
}
//指定处理响应的JavaScript函数名.
req.onreadystatechange = alertContents;
//测试传递 用户名和密码
var user_name = document.getElementById('userName').value;
var user_pwd = document.getElementById('password').value;
//open(请求方式，准确的本域域名，是否异步);
//GET或POST方式
//----GET方式请求------
//req.open('GET', url+'?user_name='+user_name+'&user_pwd='+user_pwd, true);
//req.send(null);
//----POST方式请求------
//发送请求 如果open是POST方式可以发送字符串给服务器,也可以在open的第二个参数同时加上get传输
////req.open('POST', url+'?get1='+user_name+'&get2='+user_pwd, true);
req.open('POST', url, true);
req.setRequestHeader("Content-type","application/x-www-form-urlencoded");
req.send('user_name='+user_name+'&user_pwd='+user_pwd);
}
/**
* ajax请求的回调处理函数
*/
function alertContents() {
if (req.readyState == 4) {
console.log(req.status);
if (req.status == 200) {
alert(req.response);
} else {
alert('There was a problem with the request.');
}
}
}
</script>
</body>
</html>./test.php代码如下
<?phpheader('content-type:text/html;charset=utf-8');var_dump($_POST);//获取到post传递的数据var_dump($_GET);
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