<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.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;
}
a{
text-decoration: none;
}
#fa{
display: block;
width: 100px;
height: 30px;
line-height: 30px;
text-align: center;
background: green;
color: yellow;
}
#fa:hover{
background: orange;
color: black;
}
#son{
width: 100px;
list-style: none;
display: none;
}
ul a{
display: block;
width: 100px;
height: 30px;
background: #CCC;
line-height: 30px;
text-align: center;
border-bottom: 4px solid red;
color: green;
}
</style>
<script type="text/javascript">
function in(){
var lo=document.getElementById('son');
if (lo.style.display==none)
{
lo.style.display='block';
}
else{
lo.style.display='none';
}
}
</script>
</head>
<body>
<a id="fa" href="#" onmouseover="in()">我是父目录</a>
<ul id="son">
<li><a href="#">我是子目录</a></li>
<li><a href="#">我是子目录</a></li>
<li><a href="#">我是子目录</a></li>
</ul>
<!-- <input type="button" value="点击取消！" onclick="reset()" /> -->
</body>
</html>
1、ul未使用定位不知道是否有关；
2、js初学，if的用法搞不懂对不对。
PS：0基础在家自学，不懂的没人指导，求指点！！！！