<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
margin: 0;
padding: 0;
}
#box{
position: relative;
margin: 100px auto;
width: 300px;
}
li{
list-style: none;
}
ul li{
position: absolute;
left: 0;
top: 0;
}
ol li{
width: 20px;
height: 20px;
background: yellow;
border-radius: 50%;
float: left;
text-align: center;
line-height: 20px;
margin-right: 3px;
}
ol{
position: absolute;
right: 32px;
bottom: -180px;
z-index: 99999;
}
.red{
background: red;
}
</style>
</head>
<body>
<div id="box">
<ul id="up">
<li style="z-index: 1;"><img src="a.jpg" alt="" /></li>
<li><img src="b.jpg" alt="" /></li>
<li><img src="c.jpg" alt="" /></li>
<li><img src="d.jpg" alt="" /></li>
</ul>
<ol id="down">
<li class="red">1</li>
<li>2</li>
<li>3</li>
<li>4</li>
</ol>
</div>
</body>
</html>
<script type="text/javascript">
var index = 0;//控制下标和图片对应关系
var timer = null;
var olist = document.getElementById("down").children;
var ulist = document.getElementById("up").children;
timer = setInterval( autoPlay,1500 );
function autoPlay(){
index++;
//排他思想 将所有文字样式清除 所有图片隐藏
for( var i = 0 ; i < olist.length ; i++ ){
olist[i].className = "";
ulist[i].style.display = "none";
}
//判断index越界问题
if( index == olist.length ){
index = 0;
}
//控制index对应的图片和文字对应显示
olist[index].className = "red";
ulist[index].style.display = "block";
}
//鼠标移入移出到olist上 操作定时器的停止和启动
for( let i = 0 ; i <olist.length ; i++ ){
olist[i].onmouseover = function(){
clearInterval( timer );
//获取鼠标当前移入到li上的下标
index = i-1;
autoPlay();
}
olist[i].onmouseout = function(){
timer = setInterval( autoPlay,1500 );
}
}
</script>