源：https://www.oschina.net/code/snippet_2318153_54763
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>原生js 当前时间 倒计时代码</title>
<style>
*{margin:0;padding:0;}
body{text-align:center;}
.text{margin-top:150px;font-size:14px;}
</style>
<script>
window.onload=function(){
getMyTime();
getMyTime1();
}
//1.前面补0
function p(n){
return n<10?'0'+n:n;
}
//2.倒计时
function getMyTime(){
var startDate=new Date();
var endDate=new Date('2017/4/17 11:15:00');
var countDown=(endDate.getTime()-startDate.getTime())/1000;
var day=parseInt(countDown/(24*60*60));
var h=parseInt(countDown/(60*60)%24);
var m=parseInt(countDown/60%60);
var s=parseInt(countDown%60);
document.getElementById('time').innerHTML=day+'天'+p(h)+'时'+p(m)+'分'+p(s)+'秒';
setTimeout('getMyTime()',500);
if(countDown<=0){
document.getElementById('time').innerHTML='活动结束';
}
}
//3.当前时间
function getMyTime1(){
var myDate=new Date();
var year=myDate.getFullYear();
var month=myDate.getMonth()+1;
var day=myDate.getDate();
var week=myDate.getDay();
var array=['星期日','星期一','星期二','星期三','星期四','星期五','星期六'];
var hour=myDate.getHours();
var minute=myDate.getMinutes();
var second=myDate.getSeconds();
document.getElementById('time1').innerHTML=year+'年'+month+'月'+day+'日'+' '+array[week]+' '+p(hour)+':'+p(minute)+':'+p(second);
setTimeout('getMyTime1()',500);
}
</script>
</head>
<body>
<div class="text">
<p>倒计时间：<span id="time"></span></p>
<p>当前时间：<span id="time1"></span></p>
</div>
</body>
</html>