JavaScript实现随机点名器的完整代码与思路

function show(){
 var box=window.document.getElementById("box");
 var num=Math.floor((Math.random()*100000))%namelist.length;
 box.innerHTML=namelist[num];
 mytime=setTimeout("show()",1);
 }

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title>点击按钮随机点名-样式布局参考</title>
  <style type="text/css">  
   #box {
    margin: auto;
    width: 660px;
    font-size: 66px;
    height: 94px;
    color: #138eee;
    text-align: center;
    margin-top: 200px;
   }   
   #bt {
    margin: auto;
    width: 200px;
    text-align: center;
    margin-top: 75px;
    color: #fff;
    font-size: 25px;
    cursor: pointer;
   }
  </style>
   <script type="text/javascript">
   var namelist=["张三","李四","王五","赵六","孙七"];
 var mytime=null;
 
 function doit(){
 var bt=window.document.getElementById("bt");
 if(mytime==null){
  bt.innerHTML="停止";
  show();
 }
 else{
  bt.innerHTML="开始点名";
  clearTimeout(mytime);
  mytime=null;
 }
 }
 
 function show(){
 var box=window.document.getElementById("box");
 var num=Math.floor((Math.random()*100000))%namelist.length;
 box.innerHTML=namelist[num];
 mytime=setTimeout("show()",1);
 }
   </script>
 </head>
 <body id="bodybj" style="background-color: black;">
  <div id="box">亲，准备好点名了吗？</div>
  <div id="bt" onclick="doit()">开始点名</div>
 </body>
</html>