Native JS Realizes Jiugongge Lucky Draw

In this paper, we share the specific code of JS to realize the 9-grid lottery for your reference. The specific contents are as follows

On the code:

<div class="wrapper">
    <div> Thank you for your patronage </div>
    <div>10 Ten thousand yuan in cash </div>
    <div> Thank you for your patronage </div>
    <div>iphone11</div>
    <div> Lucky draw </div>
    <div> Beautiful refrigerator </div>
    <div> Thank you for your patronage </div>
    <div>50 Yuan red envelope </div>
    <div> Thank you for your patronage </div>
  </div>
<div class="result"></div>

CSS style code:

<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>

JS code:

<script>
    var t, m, num, time, index, target, current;
    // With index value as 0 , 1 , 2 , 5 , 8 , 7 , 6 , 3 Adj. div Element is the loop target, 
    // Because with num The total number is decreasing, so the array is defined in reverse order 
    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 = ' In the lottery ...';
      result.innerHTML = '';
      // The winning goal is set to 0 To 7 Random integer of 
      target = Math.floor(Math.random() * 8);
      // The starting position is set to random, and the num Is the total number of cycles 
      num = Math.floor(Math.random() * 8) + 40;
      // Of the total number of cycles 2/3 Save, easy to adjust the time when the rate peak appears 
      // If m For the total cycle 1/2 The peak velocity appears in the middle of the total duration 
      m = Math.floor(num * 2 / 3);
      // Here if Statement can limit the winning, starting from the 1 The starting outer rings correspond clockwise respectively 7 , 6 , 5 , 4 , 3 , 2 , 1 , 0
      // Such as setting target == 6  That is, under restriction 10 Ten thousand yuan in cash, the following code is 100% Don't win a prize 
      if (target == 6|| target == 4 || target == 2 || target == 0) { 
         target++;
       }
      speed();

      function speed() {
        // Will loop the target div To an expression that converts the index value of to the total number of loops 
        index = arr[num % 8];
        // Adds a style to the current loop element and removes the previous style 
        if (current) {
          current.remove('active');
        }
        div[index].classList.add('active');
        current = div[index].classList;
        // Speed function, adjustable speed 
        t = Math.floor(Math.pow((num - m), 2) + 250);
        //1 Secondary timer, nested recursive loop control speed 
        time = setTimeout(function() {
            speed()
          }, t)
        // Judge the winning result 
        if (num == target) {
          clearTimeout(time);
          div[4].innerHTML = ' Lucky draw ';
          switch (target) {
            case 6:
              result.innerHTML = ' Congratulations on your winning ' + div[arr[target % 8]].innerHTML + ' Grand prize ';
              break;
            case 4:
              result.innerHTML = ' Congratulations on your winning ' + div[arr[target % 8]].innerHTML;
              break;
            case 2:
              result.innerHTML = ' Congratulations on your winning ' + div[arr[target % 8]].innerHTML;
              break;
            case 0:
              result.innerHTML = ' Congratulations on your winning ' + div[arr[target % 8]].innerHTML;
              break;
            default:
              result.innerHTML = div[arr[target % 8]].innerHTML;
          }
        }
        num--;
      }
    }


</script>