js实现鼠标拖拽多选功能

在JavaScript中实现一个基本的鼠标拖拽多选功能，可以通过监听鼠标事件来完成。以下是一个简单的实现示例：



<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Drag Select</title>
<style>
  .select-area {
    width: 400px;
    height: 200px;
    position: relative;
    border: 1px solid #000;
  }
  .select-box {
    background: rgba(0, 0, 255, 0.3);
    position: absolute;
    border: 1px dashed #000;
    pointer-events: none;
  }
  .item {
    width: 100px;
    height: 50px;
    position: absolute;
    top: 0;
    left: 0;
    border: 1px solid #000;
    margin: 10px;
  }
</style>
</head>
<body>
 
<div class="select-area">
  <div class="item">Item 1</div>
  <div class="item">Item 2</div>
  <div class="item">Item 3</div>
  <!-- More items here -->
</div>
 
<script>
  const selectArea = document.querySelector('.select-area');
  let startX, startY, isDragging = false;
 
  selectArea.addEventListener('mousedown', function(e) {
    startX = e.pageX - this.offsetLeft;
    startY = e.pageY - this.offsetTop;
    isDragging = true;
    const selectBox = document.createElement('div');
    selectBox.classList.add('select-box');
    selectArea.appendChild(selectBox);
  });
 
  selectArea.addEventListener('mousemove', function(e) {
    if (isDragging) {
      const selectBox = this.querySelector('.select-box');
      const x = Math.min(e.pageX - this.offsetLeft, startX);
      const y = Math.min(e.pageY - this.offsetTop, startY);
      const width = Math.abs(e.pageX - this.offsetLeft - startX);
      const height = Math.abs(e.pageY - this.offsetTop - startY);
      selectBox.style.left = `${x}px`;
      selectBox.style.top = `${y}px`;
      selectBox.style.width = `${width}px`;
      selectBox.style.height = `${height}px`;
 
      // 选中交集中的所有项
      const items = this.querySelectorAll('.item');
      items.forEach(item => {
        const itemRect = item.getBoundingClientRect();
        if (x < itemRect.left && itemRect.left < x + width
          && y < itemRect.top && itemRect.top < y + height) {
          item.classList.add('selected'); // 添加自定义的selected类来标记选中
        } else {
          item.classList.remove('selected');
        }
      });
    }
  });
 
  selectArea.addEventListener('mouseup', function() {
    isDragging = false;
    const selectBox = this.querySelector('.select-box');
    if (selectBox) {
      selectArea.removeChild(selectBox);
    }
  });
</script>
 
</body>
</html>
在这个例子中，当
js实现鼠标拖拽多选功能

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