Javascript抽奖应用：九宫格抽奖

作者：Terry2020.11.10来源：Web前端之家浏览：5562评论:0

关键词：js

分享个Javascript抽奖应用：九宫格抽奖，原生JS开发，试试吧。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>9宫格抽奖活动 - Web前端之家https://www.jiangweishan.com/</title>
    <style>
        .wrapper {
          width: 300px;
          height: 300px;
          display: flex;
          flex-flow: row wrap;
          position: absolute;
          top: 0;
          left: 0;
          right: 0;
          bottom: 0;
          margin: auto;
          border: 1px solid red;
        }
         
        .wrapper div {
          flex: none;
          width: 100px;
          height: 100px;
          box-sizing: border-box;
          border: 1px solid red;
          display: flex;
          align-items: center;
          justify-content: center;
        }
         
        .active {
          background-color: red;
        }
         
        .wrapper div:nth-child(5) {
          cursor: pointer;
        }
         
        .result {
          height: 100px;
          display: inline-block;
          position: absolute;
          top: 50px;
          left: 0;
          right: 0;
          margin: auto;
          text-align: center;
          line-height: 100px;
          font-size: 40px;
          font-weight: 700;
          color: #ff4400;
        }
    </style>
</head>
<body>
    <div class="wrapper">
        <div>谢谢惠顾</div>
        <div>十万元现金</div>
        <div>谢谢惠顾</div>
        <div>iphone12</div>
        <div>抽奖</div>
        <div>美的冰箱</div>
        <div>谢谢惠顾</div>
        <div>50元红包</div>
        <div>谢谢惠顾</div>
      </div>
    <div class="result"></div>

    <script>
        var t, m, num, time, index, target, current;
        //以索引值为0，1，2，5，8，7，6，3的div元素为循环目标，
        //因为以num总数递减的方式进行循环，故将数组倒序定义
        var arr = [3, 6, 7, 8, 5, 2, 1, 0];
        var div = document.querySelectorAll('.wrapper div');
        var result = document.querySelector('.result');
        div[4].onclick = function() {
          clearInterval(time);
          div[4].innerHTML = '抽奖中...';
          result.innerHTML = '';
          //中奖目标设为0到7的随机整数
          target = Math.floor(Math.random() * 8);
          //起始位置设为随机，且以num为总的循环数
          num = Math.floor(Math.random() * 8) + 40;
          //将总循环数的2/3保存，方便调整速率峰值出现的时间
          //若m为总循环的1/2，则速度峰值会在总时长的中间出现
          m = Math.floor(num * 2 / 3);
          //此处if语句可限制中奖，从第一个开始外圈顺时针分别对应7，6，5，4，3，2，1，0
          //如设置target == 6 即限制中十万元现金，以下代码为100%不中奖
          if (target == 6|| target == 4 || target == 2 || target == 0) { 
             target++;
           }
          speed();
     
          function speed() {
            //将循环目标div的索引值转换为循环总数的表达式
            index = arr[num % 8];
            //给当前循环元素添加样式，并移除之前的样式
            if (current) {
              current.remove('active');
            }
            div[index].classList.add('active');
            current = div[index].classList;
            //速度函数，可调试速率
            t = Math.floor(Math.pow((num - m), 2) + 20);
            //一次性定时器，嵌套递归循环控制速度
            time = setTimeout(function() {
                speed()
              }, t)
            //判断中奖结果
            if (num == target) {
              clearTimeout(time);
              div[4].innerHTML = '抽奖';
              switch (target) {
                case 6:
                  result.innerHTML = '恭喜您抽中' + div[arr[target % 8]].innerHTML + '大奖';
                  break;
                case 4:
                  result.innerHTML = '恭喜您抽中' + div[arr[target % 8]].innerHTML;
                  break;
                case 2:
                  result.innerHTML = '恭喜您抽中' + div[arr[target % 8]].innerHTML;
                  break;
                case 0:
                  result.innerHTML = '恭喜您抽中' + div[arr[target % 8]].innerHTML;
                  break;
                default:
                  result.innerHTML = div[arr[target % 8]].innerHTML;
              }
            }
            num--;
          }
        }
     
     
    </script>
</body>
</html>

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