15-举例.html

<div id='root'></div>
<script src="./react.js"></script>
<script src="./react-dom.js"></script>
<script src="./babel.min.js"></script>

<script type="text/babel">

 var arr=['aaa','bbb','ccc']

 function render(){
    ReactDOM.render((
      <div>{arr.map((item,index)=>{
      return (
        <div key={index}>
          {item}
          <button onClick={()=>moveUp(index)}>上移</button>
          <button onClick={()=>moveDown(index)}>下移</button>
        </div>
      )

    })}
    </div>),document.getElementById('root'))


 }

function moveDown(index){
  if(index===arr.length-1){
    alert('无法下移')
    return
  }
  let newArr=[]
  newArr=arr.splice(index,1)
  arr.splice(index+1,0,newArr[0])
  render()
}

function moveUp(index){
  if(index===0){
    alert('无法上移')
    return
  }
  let newArr=[]
  newArr=arr.splice(index,1)
  arr.splice(index-1,0,newArr[0])
  render()
}

render()

</script>