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我有一个包含 6 个“部分”的页面，我正在尝试将其添加到当前部分，一旦它到达视口的顶部。但是我想要它，以便在任何时候只有 1 个部分具有“活动”类。所以我需要它来添加 'active 到当前的并从所有其他人中删除它。我可以获得第一部分，但无法将其从所有其他部分中删除？

到目前为止，这是我的代码：

HTML：

    <!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">
  <link rel="stylesheet" href="/site.css">
  <title>Home</title>
</head>

<style>
  section {
    height: 100vh;
    padding: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .section1 {
    background: blue;
  }

  .section2 {
    background: red;
  }

  .section3 {
    background: green;
  }

  .section4 {
    background: purple;
  }

  .section5 {
    background: orange;
  }

  .section6 {
    background: hotpink;
  }
</style>

<body class="homepage">
  <!-- Main -->
  <main>
    <!-- Section 1 -->
    <section class="section1">
      <p>Section 1</p>
    </section>
    <!-- Section 2 -->
    <section class="section2" id="firstSection">
      <p>Section 2</p>
    </section>
    <!-- Section 3 -->
    <section class="section3">
      <p>Section 3</p>
    </section>
    <!-- Section 4 -->
    <section class="section4">
      <p>Section 4</p>
    </section>
    <!-- Section 5 -->
    <section class="section5">
      <p>Section 5</p>
    </section>
    <!-- Section 6 -->
    <section class="section6">
      <p>Section 6</p>
    </section>
  </main>

</body>
<script src="/dev.js"></script>

</html>

JS：

function getSection() {
  let sections = document.querySelectorAll('section');

  for (let a = 0; a < sections.length; a++) {
    let thisSection = sections[a];
    let bounding = thisSection.getBoundingClientRect().top;
    let height = thisSection.clientHeight;

    if (bounding <= 0) {
      thisSection.classList.add('active');
    } else {
      thisSection.classList.remove('active');
    }
  }
}

window.addEventListener("scroll", getSection);
4

1 回答 1

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如果使用 Jquery 很容易解决。您可以使用两个变量来保存目标 DOM 之前和之后的 DOM。这是一个演示

for (let a = 0; a < sections.length; a++) {
    let thisSection = sections[a];
    const beforeSection = a > 0 ? sections[a - 1] : ''
    const lastSection = a < sections.length ? sections[a + 1] : ''
    let bounding = thisSection.getBoundingClientRect().top;
    let height = thisSection.clientHeight;



    if (bounding <= 0) {
        thisSection.classList.add('active');
        if (beforeSection) {
            beforeSection.classList.remove('active')
        }
        if (lastSection) {
            lastSection.classList.remove('active')
        }
    } else {
        thisSection.classList.remove('active');
    }
}

你可以试试这个。

于 2020-06-24T09:46:54.020 回答