js实现随机点名程序

时间:2021-04-02 人气:0

最近用到了一下随机点名程序，就自己整理一下。代码实现后的截图如下。

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>随机点名</title>
 <style>
  #content{
   width: 600px;
   height: 400px;
   background: #000;
   margin: 100px auto;
   text-align: center;
   position: relative;
   line-height: 300px;
   color: dodgerblue;
   font-size: 70px;
  } 
  #btn1{
   background: #ccc;
   width: 180px;
   height: 80px;
   font-size: 30px;
   color: #f40;
   border-radius: 12px;
   position: absolute;
   bottom: 30px;
   left: 50%;
   margin-left: -90px;
   
  }
 
 </style>
</head>
<body>
 <div id="content">
  <span id="span1">
   点击开始
  </span>
  <button id="btn1">
   start
  </button>

 </div>

 <script>
  var arr = ['中国','英国','德国','美国','意大利','法国','西班牙','日本','阿联酋','荷兰','葡萄牙'];
  var $btn1 = document.getElementById('btn1');
  var $content = document.getElementById('content');
  var $span1 = document.getElementById('span1');
  var timer;//计时器
  var testNum = true;
  $btn1.onclick = function(){
   if(testNum){
    // console.log(1);
    start();
    $btn1.innerHTML = 'stop';
    testNum = false;
   }
   else{
    // console.log(0);
    stop();
    $btn1.innerHTML = 'start';
    testNum = true;
   }
  }
  function start(){
    timer = setInterval(function(){
     var num = random(0,arr.length - 1);
     $span1.innerHTML = arr[num];
    },50)
  }
  function stop(){
    clearInterval(timer);  
  }
  // 随机函数
  function random(a,b){
   var randomNum = Math.round(Math.random() * (b - a) + a);
   return randomNum;
  }  
 </script>
</body>
</html>

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