JavaScript概率函数

翻看以前的代码时，发现一个在没事的时候写的小玩意—概率函数，有点像游戏里装备升级成功率的那个玩意，权当自娱自乐。

 1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
 2 <html>
 3     <head>
 4         <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 5         <title>试试手气</title>
 6     </head>
 7     <body>
 8         <label>概率值请填写0-1之间的有效数字</label>
 9         <input id="val" type="text" value="0.000001">
10         <input id="click" type="button" value="试试手气">
11         <br/><br/>
12         <label>结果</label>
13         <input id="res" readonly="readonly" type="text" value="">
14         <script type="text/javascript">
15             function Probability(percentage, success, fail){
16                 var len = percentage.toString().length - percentage.toString().indexOf(".") - 1;
17                 var randomNum = Math.ceil(Math.random() * Math.pow(10, len));
18 
19                 if (randomNum <= percentage * Math.pow(10, len)) {
20                     success();
21                 } else {
22                     fail();
23                 }
24             }
25 
26             var probit = document.getElementById("val");
27             var result = document.getElementById("res");
28             document.getElementById("click").onclick = function(){
29                 Probability(probit.value, function(){
30                     result.value = "成功！";
31                 }, function(){
32                     result.value = "失败！";
33                 });
34             };
35         </script>
36     </body>
37 </html>