<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
*{
padding: 0;
margin: 0;
}
#uls{
width: 500px;
height: 500px;
margin: 50px auto;
}
li{
width: 150px;
height: 150px;
background: skyblue;
float: left;
list-style: none;
margin:5px;
color: #fff;
text-align: center;
line-height: 150px;
font-size: 20px;
font-weight: bold;
}
#uls li button{
width: 50px;
height: 30px;
}
.light{
width: 150px;
height: 150px;
background: #666;
color: #fff;
}
</style>
</head>
<body>
<ul id='uls'>
<li>600元优惠券</li>
<li>800元优惠券</li>
<li>1000元优惠券</li>
<li>800元优惠券</li>
<li><button id='btn1'>开始</button> <button id='btn2'>停止</button></li>
<li>600元优惠券</li>
<li>600元优惠券</li>
<li>1000元优惠券</li>
<li>800元优惠券</li>
</ul>
<script>
var btn1=document.getElementById("btn1");
var btn2=document.getElementById("btn2");
var arr=[0,1,2,5,8,7,6,3];//按这个下标依次旋转
var lis=document.getElementsByTagName("li");
var num=0; //定义初识下标
btn1.onclick=function(){
btn1.disabled=true;
time=setInterval(function(){
lis[arr[num]].className="";
num++;
if(num>7){
num=0;
}
lis[arr[num]].className="light";
},50)
}
btn2.onclick=function(){
btn1.disabled=false;
clearInterval(time);
}
</script>
</body>
</html
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