jQuery实现倒计时

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4 <meta charset="UTF-8">
 5 <script src="jquery-3.1.1.min.js"></script>
 6 <title></title>
 7 <style>
 8 .clock{width:200px;height:100px;margin:200px auto;}
 9 .hour,.min,.sec{width:40px;height:30px;font-size:20px;line-height:30px;display:inline-block;text-align: center;background:#572019;color:#FFFFFF;}
10 span:nth-child(2),span:nth-child(4){font-size:20px;}
11 </style>
12 <script>
13 $(function(){
14 function getRTime(){
15 var dateFinal=new Date("2018/07/31 14:00:00");   //截止时间
16 var dateNow=new Date();     //获得系统当前时间
17 var t=dateFinal.getTime()-dateNow.getTime();    //获取差值，单位毫秒
18 var h=(Math.floor(t/1000/60/60%24));
19 var m=(Math.floor(t/1000/60%60));
20 var s=(Math.floor(t/1000%60));
21 $(".hour").text(toDouble(h));
22 $(".min").text(toDouble(m));
23 $(".sec").text(toDouble(s));
24 }
25 function toDouble(num){
26 if(num<10){
27 return "0"+num;
28 }else{
29 return ""+num;
30 }
31 }
32 setInterval(getRTime,1000);
33 })
34 </script>
35 <head>
36 <body>
37 <div class="clock">
38 <span class="hour">00</span>
39 <span>:</span>
40 <span class="min">00</span>
41 <span>:</span>
42