index.js代码：
/* 时间倒计时 */
function TimeDown(id, endDateStr) {
//结束时间
var endDate = new Date(endDateStr);
//当前时间
var nowDate = new Date();
//相差的总秒数
var totalSeconds = parseInt((endDate - nowDate) / 1000);
//天数
var days = Math.floor(totalSeconds / (60 * 60 * 24));
//取模（余数）
var modulo = totalSeconds % (60 * 60 * 24);
//小时数
var hours = Math.floor(modulo / (60 * 60));
modulo = modulo % (60 * 60);
//分钟
var minutes = Math.floor(modulo / 60);
//秒
var seconds = modulo % 60;
//输出到页面
//document.getElementById(id).innerHTML = "还剩:" + days + "天" + hours + "小时" + minutes + "分钟" + seconds + "秒";
document.getElementById(id).innerHTML = minutes + "分" + seconds + "秒";
//延迟一秒执行自己
setTimeout(function () {
TimeDown(id, endDateStr);
}, 1000)
}
/**
* 时间倒计时
* @param id
* @param totalSeconds 倒计时多少秒
*/
function TimeDown(id, totalSeconds) {
if( totalSeconds<=0 ){
document.getElementById(id).innerHTML = "0分" + "0秒";
}else{
//天数
var days = Math.floor(totalSeconds / (60 * 60 * 24));
//取模（余数）
var modulo = totalSeconds % (60 * 60 * 24);
//小时数
var hours = Math.floor(modulo / (60 * 60));
//再取模（余数）
modulo = modulo % (60 * 60);
//分钟
var minutes = Math.floor(modulo / 60);
//再取模（秒）
var seconds = modulo % 60;
//输出到页面
//document.getElementById(id).innerHTML = "还剩:" + days + "天" + hours + "小时" + minutes + "分钟" + seconds + "秒";
document.getElementById(id).innerHTML = minutes + "分" + seconds + "秒";
//延迟一秒执行自己
setTimeout(function () {
TimeDown(id, totalSeconds-1);
}, 1000)
}
}
页面：
<!DOCTYPE html>
<html lang="en">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>时间倒计时</title>
<script src="index.js"></script>
</head>
<body>
<div id="downtime1"></div>
<div id="downtime2"></div>
<script type="text/javascript">
TimeDown1("downtime1", "2019-12-11 23:50:20");
TimeDown2("downtime2", 600);
</script>
</body>
</html>
下图使用：TimeDown2("downtime2", 600);
