<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<h1 id="date_time"></h1>
<script type="text/javascript">
function getweek(option){
// switch (option){
// case 0:
// return "星期日";
// case 1:
// return "星期一";
// case 2:
// return "星期二";
// case 3:
// return "星期三";
// case 4:
// return "星期四";
// case 5:
// return "星期五";
// case 6:
// return "星期六";
// default:
// break;
var iweek="日一二三四五六".charAt(option);
return "星期"+iweek;
}
function showTime(){
var dateTime=new Date();
var year=dateTime.getFullYear();
var mouth=dateTime.getMonth()+1;
mouth=mouth<10?"0"+mouth:mouth;
var date=dateTime.getDate();
date=date<10?"0"+date:date;
var hour=dateTime.getHours();
hour=hour<10?"0"+hour:hour;
var minute=dateTime.getMinutes();
minute=minute<10?"0"+minute:minute;
var second=dateTime.getSeconds();
second=second<10?"0"+second:second;
var day=dateTime.getDate()+1;
var week=getweek(day);
dateTime=year+"年"+mouth+"月"+date+"日"+" "+week+" "+hour+":"+minute+":"+second;
document.getElementById("date_time").innerHTML=dateTime;
}
showTime();
setInterval("showTime()",1000);//间隔多少毫秒执行一次方法
</script>
</body>
</html>
原文：https://www.cnblogs.com/ll1130/p/14849352.html