JS倒计时
浏览器界面倒计时，用js就实现
设置时间戳，进行倒计时。比如距离活动结束时间等等
代码如下：
1 <html>
2 <head>
3 <meta charset="UTF-8">
4 <title>js简单时分秒倒计时</title>
5 <script type="text/javascript">
6 function countTime() {
7 //获取当前时间
8 var date = new Date();
9 var now = date.getTime();
10 //设置截止时间
11 var str="2017/9/26 00:00:00";
12 var endDate = new Date(str);
13 var end = endDate.getTime();
14
15 //时间差
16 var leftTime = end-now;
17 //定义变量 d,h,m,s保存倒计时的时间
18 var d,h,m,s;
19 if (leftTime>=0) {
20 d = Math.floor(leftTime/1000/60/60/24);
21 h = Math.floor(leftTime/1000/60/60%24);
22 m = Math.floor(leftTime/1000/60%60);
23 s = Math.floor(leftTime/1000%60);
24 }
25 //将倒计时赋值到div中
26 document.getElementById("_d").innerHTML = d+"天";
27 document.getElementById("_h").innerHTML = h+"时";
28 document.getElementById("_m").innerHTML = m+"分";
29 document.getElementById("_s").innerHTML = s+"秒";
30 //递归每秒调用countTime方法，显示动态时间效果
31 setTimeout(countTime,1000);
32
33 }
34 </script>
35 </head >
36 <body onload="countTime()" >
37 <div>
38 <span id="_d">00</span>
39 <span id="_h">00</span>
40 <span id="_m">00</span>
41 <span id="_s">00</span>
42 </div>
43 </body>
44 </html>
运行结果：
