TYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
*{margin:0; padding:0;}
.abc{width:720px; height:450px; margin:0 auto;
position:relative; left:0; top:0;}
.www{width:120px; height:20px; padding:2px 0 2px 9px;
position:absolute; right:20px; bottom:20px;}
.www ul li{list-style:none; float:left; margin-right:10px; background:#F60;
width:20px; height:20px; text-align:center; color:white;
cursor:pointer; border-radius:50%;}
</style>
<script type="text/javascript">
function dianji(a){
document.getElementById('pic').src=a+'.jpg';
document.getElementById('bg'+a).style.backgroundColor='black';
}
</script>
</head>
<body>
<div class="abc">
<img src="1.jpg" id="pic"/>
<div class="www">
<ul id="bbb">
<li id="bg1" onclick="dianji(1)">1</li>
<li id="bg2" onclick="dianji(2)">2</li>
<li id="bg3" onclick="dianji(3)">3</li>
<li id="bg4" onclick="dianji(4)">4</li>
</ul>
</div>
</div>
</body>
</html>
新手刚开始自学JS，学到带参函数了，写了一个点击切图，假设点击②后大图片变了，小②的背景变成了黑色，怎么写才能点击③后②的黑色背景消失呢？就是点击另一个切图图标的时候其他的图标背景色恢复原状。。。利用简单地方法怎么写？新手求教了，谢谢了
