版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq_38355456/article/details/78542803
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS实现倒计时(天数,时,分,秒)</title>
</head>
<body>
<h2>剩余时间:</h2>
<div id="timer"></div>
<script language="javascript" type="text/javascript">
timer('2018-11-20 12:00:00','day');
/**
* 入参第一个为时间字符串，第二个参数为模式选择，如果传入'day'，按天数倒计时到秒，不传值，按小时精确到秒
* @param timeStr
* @param item
*/
function timer(timeStr,item){
setInterval(function(){
let nowTime = new Date(timeStr) - new Date;
let minutes = parseInt(nowTime / 1000 / 60 % 60, 10);//计算剩余的分钟
let seconds = parseInt(nowTime / 1000 % 60, 10);//计算剩余的秒数
minutes = checkTime(minutes);
seconds = checkTime(seconds);
if(item==='day'){
let days = parseInt(nowTime / 1000 / 60 / 60 / 24, 10); //计算剩余的天数
let hours = parseInt(nowTime / 1000 / 60 / 60 % 24, 10); //计算剩余的小时
days = checkTime(days);
hours = checkTime(hours);
document.getElementById('timer').innerHTML=days + "天" + hours + "小时" + minutes + "分" + seconds + "秒";
}else{
let hours = parseInt(nowTime / ( 1000 * 60 * 60), 10); //计算剩余的小时
hours = checkTime(hours);
document.getElementById("timer").innerHTML = hours + "小时" + minutes + "分" + seconds + "秒";
}
},1000);
}
function checkTime(i) { //将0-9的数字前面加上0，例1变为01
if (i < 10) {
i = "0" + i;
}
return i;
}
</script>
</body>
</html>