js实现拖拽排序

在 JavaScript 中实现拖拽排序，通常会结合 HTML5 的拖放 API 来完成。以下是一个基础的示例代码，展示如何实现列表项的拖拽排序功能：

<!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">
  <style>
    .draggable-list {
      list-style-type: none;
      padding: 0;
    }

    .draggable-item {
      padding: 10px;
      border: 1px solid #ccc;
      margin-bottom: 5px;
      cursor: move;
    }
  </style>
</head>

<body>
  <ul class="draggable-list" id="draggableList">
    <li class="draggable-item" draggable="true">Item 1</li>
    <li class="draggable-item" draggable="true">Item 2</li>
    <li class="draggable-item" draggable="true">Item 3</li>
    <li class="draggable-item" draggable="true">Item 4</li>
  </ul>

  <script>
    const list = document.getElementById('draggableList');
    let draggedItem = null;

    list.addEventListener('dragstart', (e) => {
      draggedItem = e.target;
      e.dataTransfer.effectAllowed = 'move';
    });

    list.addEventListener('dragover', (e) => {
      e.preventDefault();
      const overItem = e.target.closest('.draggable-item');
      if (overItem && overItem !== draggedItem) {
        const rect = overItem.getBoundingClientRect();
        const offset = e.clientY - rect.top;
        if (offset < rect.height / 2) {
          list.insertBefore(draggedItem, overItem);
        } else {
          list.insertBefore(draggedItem, overItem.nextSibling);
        }
      }
    });

    list.addEventListener('dragend', () => {
      draggedItem = null;
    });
  </script>
</body>

</html>

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