原生js实现随机点名功能

时间:2021-04-02 人气:0
原生js实现随机点名，js部分有注释
<!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>Document</title>
  <style>
    *{
      padding: 0;
      margin: 0;
      
    }
    .wrapper{
      width: 800px;
      margin: 10px auto;
      border: 2px solid #ccc; 
      text-align: center;
    }
    .lucking{
      width: 200px;
      height: 180px;
      border: 1px solid #000;
      position: relative;
    }
    .lucking img{
      position: absolute;
      left: 0;
      bottom: 0;
    }
    .wrapper ul li{
      width: 100px;
      height: 50px;
      line-height: 50px;
      text-align: center;
      margin: 4px;
      border:2px solid #ccc;
      border-radius: 5px;
      /* 不设置float:left的原因
      1： 浮动不能让父盒子撑开高度 
      2： display:inline-block 具有行内元素的属性特征，给父盒子加text-align:center 可使其居中
      */
      display: inline-block;
    }
    .wrapper button{
      margin-top: 20px;
      width: 80px;
      height: 40px;
      border: none;
      background-color: #ddd;
      border-radius: 5px;
      font-weight: 700;
      outline: none;
      cursor: pointer;
    }
    .wrapper .active{
      background-color: #f1084a;
      font-weight: 700;
    }
  </style>
</head>
<body>
  <div class="wrapper" id="_wrapper">
    <ul id="_ul"></ul>
    <button class="start">开始点名</button>
    <button class="stop">停止</button>
    <div class="lucking" id="_lucking">
      <p></p>
      <img src="1.gif" alt="">
    </div>
  </div>
</body>
</html>
<script>
  var array = ['杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦','李易峰','杨雨婷','张蓓','王洁','邓伦'];
  // 获取元素
  var _wrapper = document.getElementById('_wrapper');
  var ul = document.getElementById('_ul');;
  var timer = null;
  init();

  function init(){
  // 动态创建li
  for(var i = 0; i < array.length;i++)
  {
    var oli = document.createElement('li');
    oli.innerHTML = array[i];
    ul.appendChild(oli);
  }
  // 点击
    click();
  }
  function click(){
    // 获取start按钮
    var start = _wrapper.getElementsByTagName('button')[0];
    var stop = _wrapper.getElementsByTagName('button')[1];
    var lucking = document.getElementById('_lucking');
    // 定时器
    start.addEventListener('click',function(){
      clearInterval(timer);
      timer = setInterval(function(){
        // 获得随机数
        var random = Math.floor(Math.random()*array.length);
        for(var i = 0;i < array.length;i++)
        {
          ul.children[i].className = '';
        }
        ul.children[random].className = 'active';
      },50);
    });
    stop.addEventListener('click',function(){
      clearInterval(timer);
      // 找到此时的元素
      var active = document.getElementsByClassName('active')[0];
      lucking.children[0].innerText = "幸运儿：" + active.innerText;
    })
  }
</script>
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