Math.random()随机生成车牌号

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" lang="en">

   <head>
       <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
       <title>随机生成车辆号牌</title>
       <script type="text/javascript" src="js/jquery-1.8.3.min.js"></script>
       <script type="text/javascript">
           //
           //省的简称（一个汉字）
           //城市的编号
           //·对焦符号
           //五位的数字或者字母（不包含字母I和O）
           $(function() {
               $("#getCarId").click(function() {
                   console.debug("随机数：" + Math.random());
                   var shi = new Array("A", "B", "C");
                   var carId = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "A", "B", "C", "D", "E", "F", "G", "H", "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z");

                   var $objArr = $("input[name='choose']");
                   var count = 0;
                   for(var i = 0; i < $objArr.length; i++) {
                       if($objArr[i].checked) {
                           count = $($objArr[i]).val();
                       }
                   }
                   console.debug("选择生成" + count + "个号牌！");
                   $("div#main").empty();
                   for(var j = 0; j < count; j++) {
                       var shiIndex = parseInt(Math.random() * 3);
                       //console.debug("随机生成0-2之间的数（包含0和2）：" + shiIndex);
                       var carNumber = "云" + shi[shiIndex] + "·";
                       console.debug("随机生成车牌对焦点前面的内容：" + carNumber);
                       for(var i = 0; i < 5; i++) {
                           carNumber += carId[parseInt(Math.random() * carId.length - 1)];
                       }
                       console.debug("生成的号牌是：" + carNumber);

                       //添加到页面上
                       var $divObj = $("<div></div>");
                       $divObj.addClass("carId");
                       //$divObj.attr("class","carId");
                       $divObj.text(carNumber);
                       $("div#main").append($divObj);
                   }
               });
           });
       </script>
       <style type="text/css">
           div.carId {
               220px;
               height: 50px;
               background-color: mediumblue;
               color: white;
               font-family: "微软雅黑";
               font-size: 26pt;
               text-align: center;
               border: double 4px white;
               border-radius: 10px;
               float: left;
           }
       </style>
   </head>

   <body>
       <input type="radio" name="choose" value="10" />10个
       <input type="radio" name="choose" value="20" checked="checked" />20个
       <input type="radio" name="choose" value="50" />50个
       <input type="button" value="随机生成" id="getCarId" />
       <div id="main">
           
       </div>
   </body>

</html>