知识库

html
<!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>Document</title>
  <style>
    #container {
      position: relative;
      width: 300px;
      height: 200px;
      border: 3px solid black;
      margin: 0 auto;
    }

    #box1 {
      width: 100px;
      height: 100px;  
      background-color: pink;
      position: absolute;
      cursor: move;
    }
  </style>
</head>
<body>
  <div id="container"></div>
  <div id="box1" draggable="true"></div>

  <script>
    /*
      H5的drag事件: 可以把一个元素从当前位置拖拽到指定容器中
        dragstart 开始拖拽触发
        dragend 拖拽结束触发
        dragover 元素在容器内拖拽时触发(鼠标不动也会一直触发)
        dragenter 元素进入容器时触发
        dragleave 元素离开容器时触发
        drop 结束拖拽时如果元素在容器中则触发

        给要拖拽的元素设置可被拖拽属性
        draggable="true"
    */

    box1.ondragstart = function (event) {
      // event -> DragEvent: 拖拽事件对象
      // 拖拽事件对象上有个属性 event.dataTransfer -> DataTransfer实例, 有三个方法
      // setData(类型标识, 值) 类型标识: text/plain text/html text/url-list... 值: 最后都会变为字符串
      // getData(类型标识) 只能在drop中得到
      // clearData(类型标识)
      event.dataTransfer.setData('text/plain', this.id)
    }

    container.ondragover = function (event) {
      event.preventDefault()
    }

    container.ondrop = function (event) {
      event.preventDefault()
      let id = event.dataTransfer.getData('text/plain')
      let ele = document.getElementById(id)
      container.appendChild(ele)
      ele.style.top = 0
      ele.style.left = 0
      ele.setAttribute('draggable', false)
    }
  </script>
</body>
</html>