JavaScriptjQuery 倒计时 非常简单
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<span id="timespan"></span>
</body>
</html>
<script src="http://libs.baidu.com/jquery/1.11.3/jquery.min.js"></script>
<script>
var starttime = new Date("2020/11/20");
setInterval(function () {
var nowtime = new Date();
var time = starttime - nowtime;
var day = parseInt(time / 1000 / 60 / 60 / 24);
var hour = parseInt(time / 1000 / 60 / 60 % 24);
var minute = parseInt(time / 1000 / 60 % 60);
var seconds = parseInt(time / 1000 % 60);
$("#timespan").html(day + "天" + hour + "小时" + minute + "分钟" + seconds + "秒");
}, 1000);
</script>