React实现轮播
思路
- 使用全局的state进行状态管理
- 设置全局下标，对当前的图片下表进行样式划分
- 定时循环人物便利改变全局下标
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<style>
ul{
width: 100%;
text-align: center;
list-style-type: circle;
}
ul>li{
width: 2%;
float: left;
}
img{
width: 100%;
}
</style>
<title>轮播事件</title>
</head>
<body>
<div id="root" style="max-width: 700px;margin: 0 auto;"></div>
</body>
<script src="./js/react.development.js"></script>
<script src="./js/react-dom.development.js"></script>
<script src="./js/babel.min.js"></script>
<script type="text/babel">
window.οnlοad=()=>{
class Img extends React.Component{
constructor(props) {
super(props);
this.state={
listImg:[
'./img/banner1.jpg',
'./img/banner2.jpg',
'./img/banner3.jpg',
'./img/banner4.jpg',
'./img/banner5.jpg',
],
index:0
}
}
//计时器执行
indexChange(){
if(this.state.index == this.state.listImg.length-1){
this.setState({
index:0
})
}else{
// this.state.index++;
this.setState({
index:this.state.index+1
})
console.log(this.state.index);
}
}
componentDidMount(){
setInterval(()=>{
this.indexChange();
},2000)
}
render(){
let {listImg,index} = this.state;
let imgList=listImg.map((item,imgIndex)=>{
return <img src={item} key={imgIndex} style={{'display':index == imgIndex ? 'block' : 'none'}} className='img'/>
})
let liList=listImg.map((item2,imgIndex2)=>{
return <li key={imgIndex2} style={{'listStyleType':index == imgIndex2 ? 'initial' :'circle'}}></li>
})
return (
<div>
{imgList}
<div>
<ul>
{liList}
</ul>
</div>
</div>
)
}
}
ReactDOM.render(
<Img />,
document.getElementById("root")
)
}
</script>
</html>