html-拖放-Drag&Drop

用处及优势

提供专门的拖拽与投放的API
出发多个事件，可控制鼠标的形状与移动是的效果
可以跨页面拖放

拖放API的基本操作语法

　　draggabel属性

　　拖拽事件-ondragstart , drag , dragend

　　拖放事件-dragenter , dragover , drop

　　dataTransfer对象- setData / getData / setDragImage

实现拖拽垃圾桶效果

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    body{
      margin: 0;
    }
    ul{
      overflow: hidden;
      padding: 0;
      margin: 0;
    }
    li{
      width: 100px;
      height: 50px;
      line-height: 50px;
      text-align: center;
      border: 1px solid #000;
      /* margin: 20px; */
      float: left;
      list-style: none;
    }
    #out{
      width: 100px;
      height: 150px;
      line-height: 150px;
      margin: 50px;
      border: 1px solid #000;
      text-align: center;
    }
  </style>
</head>
<body style="position:relative">

  <ul>
    <li draggable="true">白色垃圾</li>
    <li draggable="true">生活垃圾</li>
    <li draggable="true">厨余垃圾</li>
    <li draggable="true">有害垃圾</li>
    <li draggable="true">可回收垃圾</li>
  </ul>

  <p id="txt"></p>


  <div id="out">垃圾箱</div> 

</body>
  <script type="text/javascript">
    window.onload=function(){
      let ali=document.getElementsByTagName('li')
      let oDiv=document.getElementById("out")
      let txt=document.getElementById("txt")
      let targetLi=null  //用来储存当前拖拽的dom元素
      let img=document.createElement('img')//定义拖拽的图片
      img.src='img/1111.jpg'
      //给没给拖拽元素赋方法
      for(var i=0;i<ali.length;i++){
        //开始
        ali[i].ondragstart=function(ev){
          this.style.background='yellow'
          targetLi=this
          ev.dataTransfer.setData('Text',this.innerHTML) //文本数据的携带
          // ev.dataTransfer.setDragImage(img,20,20)
        }
        //结束
        ali[i].ondragend=function(e){
          
          this.style.background=''
        }
      }
      oDiv.ondragenter=function(){
        this.style.borderColor='red'
      }
      oDiv.ondragover=function(e){
        // console.log(e)
        e.preventDefault()
      }
      oDiv.ondragleave=function(e){
        this.style.borderColor='#000'
      }
      oDiv.ondrop=function(ev){
        this.style.borderColor='#000'
        let oText=ev.dataTransfer.getData('Text')
        txt.innerHTML='删除的是:'+ oText
        targetLi.parentNode.removeChild(targetLi)
      }
    }
  </script>
</html>

实现拖动效果

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    body{
      margin: 0;
    }
    ul{
      overflow: hidden;
      padding: 0;
      margin: 0;
    }
    li{
      width: 100px;
      height: 50px;
      line-height: 50px;
      text-align: center;
      border: 1px solid #000;
      /* margin: 20px; */
      float: left;
      list-style: none;
    }
  </style>
</head>
<body style="position:relative">

  <ul>
    <li draggable="true">白色垃圾</li>
    <li draggable="true">生活垃圾</li>
    <li draggable="true">厨余垃圾</li>
    <li draggable="true">有害垃圾</li>
    <li draggable="true">可回收垃圾</li>
  </ul>

</body>
  <script type="text/javascript">
    window.onload=function(){
      let ali=document.getElementsByTagName('li')
      let oDiv=document.getElementById("out")
      let txt=document.getElementById("txt")
      let targetLi=null  //用来储存当前拖拽的dom元素
      let img=document.createElement('img')//定义拖拽的图片
      img.src='img/1111.jpg'
      let pageY=0 //start偏移量
      let pageX=0
      //给没给拖拽元素赋方法
      for(var i=0;i<ali.length;i++){
        //开始
        ali[i].ondragstart=function(ev){
          console.log(ev,1)
          pageY=ev.pageY
          pageX=ev.pageX
          this.style.background='yellow'
          targetLi=this
          ev.dataTransfer.setData('Text',this.innerHTML) //文本数据的携带
          // ev.dataTransfer.setDragImage(img,20,20)
        }
        //结束
        ali[i].ondragend=function(e){
          this.style.position='absolute'
          let top=this.style.top?Number(this.style.top.replace('px','')):0
          let left=this.style.left?Number(this.style.left.replace('px','')):0
          this.style.top=top+e.pageY-pageY+'px'
          this.style.left=left+e.pageX-pageX+'px'
          this.style.background=''
        }
      }
    }
  </script>
</html>