PROSAGA码农传奇-JS-如何操作每个滚动运动的值？

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    移动
     <code>
      var sum = 0
    </code>
     超出触发功能。它在您的实现中的每个滚动上设置为零：
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       <pre class="snippet-code-js lang-js prettyprint-override">
        <code>
          var sum = 0;

$(window).on('wheel', function(e) {

var delta = e.originalEvent.deltaY;
    
    if (delta > 0){
        sum++;
        console.log("going down");
        console.log(sum);

} else {
        if (sum > 0) {
          sum--;
        }
        console.log("going up");
        console.log(sum);
    }
    return false;
});
        </code>
      </pre>
       <pre class="snippet-code-css lang-css prettyprint-override">
        <code>
          html,
  body{
    height: 100%;
  }
  #firstbox{
    background: red;
  }

#second_box{
    background: blue;
  }

#third_box{
    background: black;
  }

.general{
    width: 100%;
    height: 100%;
  }

header{
      width: 100%;
      height: 100%;
  }
  img{
      width: 100%;
      height: 100%;
  }
        </code>
      </pre>
       <pre class="snippet-code-html lang-html prettyprint-override">
        <code>
          <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="firstbox" class="general">
      <header><img src="https://cdn.pixabay.com/photo/2017/06/05/20/10/blue-2375119_960_720.jpg" alt="image here"></header>
  </div>
  <div id="second_box" class="general">

</div>

</div>
        </code>
      </pre>
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