<!DOCTYPE html>
<html >
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<img src="img/1.jpeg" id="flower">
<br>
<button id="prve">上</button>
<button id="next">下</button>
<script>
// 获取id
var flower=document.getElementById('flower');
var nextbtn=document.getElementById('next');
var prve=document.getElementById('prve');
var minindex=1; maxindex=4;currentindex=minindex;
//定义点击事件
nextbtn.onclick=function(){
currentindex++;
if(currentindex==maxindex)
{
currentindex=1;
}
flower.setAttribute('src','img/'+currentindex+'.jpeg')
}
prve.onclick=function(){
currentindex--;
if(currentindex==minindex)
{
currentindex=4;
}
flower.setAttribute('src','img/'+currentindex+'.jpeg')
}
</script>
</body>
</html>