<p id="labTime">
<script type="text/javascript">
//取客户端时间
setInterval("labTime.innerText=new Date().toLocaleString()", 1000) //每1000毫秒(即1秒) 执行一次本段代码
</script>
</p>
获取服务器时间：
var xmlHttp = false;
//获取服务器时间
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e2) {
xmlHttp = false;
}
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
xmlHttp = new XMLHttpRequest();
}
xmlHttp.open("GET", "null.txt", false);
xmlHttp.setRequestHeader("Range", "bytes=-1");
xmlHttp.send(null);
severtime = new Date(xmlHttp.getResponseHeader("Date"));
//获取服务器日期
var year = severtime.getFullYear();
var month = severtime.getMonth() + 1;
var date = severtime.getDate();
//获取服务器时间
var hour = severtime.getHours();
var minu = severtime.getMinutes();
var seco = severtime.getSeconds();
var week = ' 星期' + '日一二三四五六'.charAt(severtime.getDay());
//格式化输出服务器时间
function getSeverTime() {
seco++;
if (seco == 60) {
minu += 1;
seco = 0;
}
if (minu == 60) {
hour += 1;
minu = 0;
}
if (hour == 24) {
date += 1;
hour = 0;
}
//日期处理
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
if (date == 32) {
date = 1;
month += 1;
}
} else if (month == 4 || month == 6 || month == 9 || month == 11) {
if (date == 31) {
date = 1;
month += 1;
}
} else if (month == 2) {
if (year % 4 == 0 && year % 100 != 0) {//闰年处理
if (date == 29) {
date = 1;
month += 1;
}
} else {
if (date == 28) {
date = 1;
month += 1;
}
}
}
if (month == 13) {
year += 1;
month = 1;
}
sseco = addZero(seco);
sminu = addZero(minu);
shour = addZero(hour);
sdate = addZero(date);
smonth = addZero(month);
syear = year;
innerdata = "现在时间：";
document.getElementById("servertime").innerHTML = innerdata + syear + "-" + smonth + "-" + sdate + " " + shour + ":" + sminu + ":" + sseco + " " + week;
setTimeout("getSeverTime()", 1000);
setTimeout("getClientTime()", 100);
}
function addZero(num) {
num = Math.floor(num);
return ((num <= 9) ? ("0" + num) : num);
}
<body onload="getSeverTime();" > //放到body里面让浏览器加载时运行
<p id="servertime"></p> //把这个放在要显示的地方
</body>
原文：https://blog.csdn.net/bingle14/article/details/50965666