JS原生代码之倒计时抢购

　　刚刚用了一点时间把完善了的倒计时抢购功能又做了一遍，这回用的是原声代码，没有引入jquery库，虽然明显感觉原生代码量要多一些，但是写出来个小功能还是很有成就感的。需要注意的就是代码顺序执行的问题，一定要思路清晰。要不然代码顺序写错，有些功能还是实现不了的。

　　学到了原声js改变input的disabled的属性值，因为想让倒计时结束的同时，抢购按钮可以被点击。代码为：document.getElementById("buy").disabled = "";或者disabled的值为false也可以。
　　下面是我编写的代码，哪里不完善，还请大神指点。

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>倒计时抢购</title>
 6 </head>
 7 <body>
 8     <span id="time"></span>
 9     <input type="button" value="开始抢购" id="buy" disabled="true">
10     <script>
11         function Time(){
12             var date = new Date();
13             var nowhour = date.getHours();
14             var nowmin = date.getMinutes();
15             var nowsec = date.getSeconds();
16             var finalhour = 22;
17             var finalmin = 22;
18             var finalsec = 22;
19             var finals = finalhour * 3600 + finalmin * 60 + finalsec;
20             var nows = nowhour * 3600 + nowmin * 60 + nowsec;
21             var showhour = parseInt((finals - nows)/3600);
22             var showmin = parseInt((finals - nows)%3600/60);
23             var showsec = (finals - nows)%60;
24              if(showsec<10){
25                 showsec = "0" + showsec;
26             }
27             if(showmin<10){
28                 showmin = "0" + showmin;
29             }
30             if(showhour<10){
31                 showhour = "0" + showhour;
32             }
33             document.getElementById("time").innerHTML = "距离22点22分22秒还有：" + showhour + ":" + showmin + ":" + showsec;
34             if(showhour == "00" && showmin == "00" && showsec =="00"){
35                 clearInterval(t);
36                 document.getElementById("buy").disabled="";
37             }
38         }
39         Time();
40         var t = setInterval(Time,1000);
41     </script>
42 </body>
43 </html>