JS实现倒计时

<!DOCTYPE html>

<html>

<head>

<title>js倒计时</title>

function countTime() {

//获取当前时间

var date = new Date();

var now = date.getTime();

//设置截止时间

var str = "2020/3/28 00:00:00";

var endDate = new Date(str);

var end = endDate.getTime();

//时间差

var leftTime = end - now;

//定义变量 d,h,m,s保存倒计时的时间

var d, h, m, s;

if (leftTime >= 0) {

d = Math.floor(leftTime / 1000 / 60 / 60 / 24);

h = Math.floor(leftTime / 1000 / 60 / 60 % 24);

m = Math.floor(leftTime / 1000 / 60 % 60);

s = Math.floor(leftTime / 1000 % 60);

}

//将倒计时赋值到div中

document.getElementById("_d").innerHTML = d + "天";

document.getElementById("_h").innerHTML = h + "时";

document.getElementById("_m").innerHTML = m + "分";

document.getElementById("_s").innerHTML = s + "秒";

//递归每秒调用countTime方法，显示动态时间效果

setTimeout(countTime, 1000);

}

</script>

</head>

<div>

</div>

</body>

</html>