CSS滚动特效

主要思路：让奇数的盒子左移至视窗外，偶数的盒子右移至视窗外，然后window对象添加滚动监听事件，滚动到相应区域，外移的盒子就移动回来

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Scroll Animation</title>

  <link rel="stylesheet" href="style.css">
</head>
<body>
  <h1>Scroll to see the animation</h1>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>
  <div class="box">
    <h2>content</h2>
  </div>

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

*{
  box-sizing: border-box;
}

body{
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  overflow-x: hidden;
}

/* h1{
  margin: 10px;
} */


.box{
  display: flex;
  justify-content: center;
  align-items: center;
  width: 400px;
  height: 200px;
  background-color: cyan;
  color: #fff;
  font-size: 32px;
  margin: 10px;
  border-radius: 10px;
  box-shadow: 2px 4px 5px rgba(0,0,0,0.3);
  transition: transform 2s ease;
}


/* 所有奇数元素 */
.box:nth-of-type(odd) {
  transform: translateX(-400%);
}

/* 所有偶数元素 */
.box:nth-of-type(even) {
  transform: translateX(400%);
}

.box.show{
  transform: translateX(0);
}

const boxList = document.querySelectorAll('.box')

window.addEventListener('scroll', checkBox)

checkBox()

function checkBox() {
  // window.innerHeight为浏览器内容区域高度
  const showTop = window.innerHeight * 4 / 5
  
  boxList.forEach(box => {
    // box.getBoundingClientRect().top为box元素距离顶部的距离
    const boxTop = box.getBoundingClientRect().top

    if (boxTop < showTop) {
      box.classList.add('show')
    } else {
      box.classList.remove('show')
    }
  })
}