限制 JavaScript 中的功能范围（滑块用例）？

Question

在下面的脚本中，当有一个滑块时代码有效，但是当页面上的滑块数量超过一个时，下一个滑块不起作用。

当我们在页面上有多个滑块时，如何更改此脚本以使每个滑块“可拖动功能”单独工作且不重叠？

需要进行哪些更改才能使此代码 “可拖动功能” 对每个滑块单独工作？

如何使用“querySelectorAll”和“forEach”来处理这个问题？

const slider = document.querySelector('.items');
let isDown = false;
let startX;
let scrollLeft;

slider.addEventListener('mousedown', (e) => {
  isDown = true;
  slider.classList.add('active');
  startX = e.pageX - slider.offsetLeft;
  scrollLeft = slider.scrollLeft;
});
slider.addEventListener('mouseleave', () => {
  isDown = false;
  slider.classList.remove('active');
});
slider.addEventListener('mouseup', () => {
  isDown = false;
  slider.classList.remove('active');
});
slider.addEventListener('mousemove', (e) => {
  if (!isDown) return;
  e.preventDefault();
  const x = e.pageX - slider.offsetLeft;
  const walk = (x - startX) * 3; //scroll-fast
  slider.scrollLeft = scrollLeft - walk;
});

.items,
.items_1 {
  position: relative;
  width: 90%;
  background: green;
  overflow-x: scroll;
  overflow-y: hidden;
  white-space: nowrap;
  transition: all 0.2s;
  transform: scale(0.98);
  will-change: transform;
  user-select: none;
  cursor: pointer;

  margin: 2rem auto;
  border: 3px solid violet;

}

.item {
  display: inline-block;
  background: red;
  min-height: 50px;
  min-width: 150px;
  margin: .5rem;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <title>slider</title>
  <link rel="stylesheet" href="./style.css">
</head>


<body>

  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>


  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>

  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>


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

</body>

</html>

Answer 1

How can I handle this with " querySelectorAll " and " forEach " ?

只需将声明状态变量并将事件处理程序附加到一个滑块的代码放入这样的循环中：

const sliders = document.querySelectorAll('.items');
for (const slider of sliders) {
  let isDown = false;
  let startX;
  let scrollLeft;

  slider.addEventListener('mousedown', (e) => {
    isDown = true;
    slider.classList.add('active');
    startX = e.pageX - slider.offsetLeft;
    scrollLeft = slider.scrollLeft;
  });
  slider.addEventListener('mouseleave', () => {
    isDown = false;
    slider.classList.remove('active');
  });
  slider.addEventListener('mouseup', () => {
    isDown = false;
    slider.classList.remove('active');
  });
  slider.addEventListener('mousemove', (e) => {
    if (!isDown) return;
    e.preventDefault();
    const x = e.pageX - slider.offsetLeft;
    const walk = (x - startX) * 3; //scroll-fast
    slider.scrollLeft = scrollLeft - walk;
  });
}

.items {
  position: relative;
  width: 90%;
  background: green;
  overflow-x: scroll;
  overflow-y: hidden;
  white-space: nowrap;
  transition: all 0.2s;
  transform: scale(0.98);
  will-change: transform;
  user-select: none;
  cursor: pointer;

  margin: 2rem auto;
  border: 3px solid violet;

}
.items.active {
  border-color: blue;
}

.item {
  display: inline-block;
  background: red;
  min-height: 50px;
  min-width: 150px;
  margin: .5rem;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <title>slider</title>
  <link rel="stylesheet" href="./style.css">
</head>


<body>

  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>


  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>

  <div class="items">

    <div class="item"></div>
    <div class="item"></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>
    <div class="item "></div>

  </div>


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

</body>

</html>

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