<html>
<head>
<meta charset="UTF-8">
<title>js简单时分秒倒计时</title>
<script type="text/javascript">
function countTime() {
//获取当前时间
var date = new Date();
var now = date.getTime();
//设置截止时间
var str="2018/12/17 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0-9的数字前面加上0，例1变为01
d = checkTime(d);
h = checkTime(h);
m = checkTime(m);
s = checkTime(s);
function checkTime(i){
if (i<10) {
i = "0"+i;
}
return i;
}
//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 >
<body onload="countTime()" >
<div>
<span id="_d">00</span>
<span id="_h">00</span>
<span id="_m">00</span>
<span id="_s">00</span>
</div>
</body>
</html>