客户端代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>动态显示时间</title>
</head>
<script language="javascript">
var xmlHttp;
function createXMLHttpRequest(){
if(window.ActiveXObject){
xmlHttp = new ActiveXObject("microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
else{
alert("创建请求失败");
}
}
function sendRequest(){
createXMLHttpRequest();
url = "time_check.php";
xmlHttp.onreadystatechange = callback;
xmlHttp.open('GET',url,true);
xmlHttp.send(null);
}
function callback(){
if(xmlHttp.readyState ==4){
if(xmlHttp.status == 200){
document.getElementById("time").innerHTML = xmlHttp.responseText;
setTimeout("sendRequest()",1000);
}
}
}
</script>
<body>
<input type="button" value="check it" onclick="sendRequest();" />
<br/>
<span id="time"></span>
</body>
</html>
服务器端代码：
<?php
header("cache-control:no-cache,must-revalidate"); //取消php页面缓存的设置
header('Content-type: text/html;charset=GB2312');
$showtime = date("北京时间Y年m月d日H:i:s");
echo $showtime;
?>