js写法下拉框
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
body,ul,li{ margin:0; padding:0;}
.box{ width:400px; margin:50px auto;}
.box li{ list-style:none; cursor:pointer;}
.box ul{ float:left; width:100px; margin-right:10px; text-align:center; height:30px; line-height:30px; background:#999;}
.box ul li ul{ display:none; width:100px; text-align:center; }
.box li ul li{ background:#CCC; height:30px; line-height:30px;}
</style>
</head>
<body>
<div class="box">
<ul>
<li onMouseOver="document.getElementById('list_1').style.display='block';" onMouseOut="document.getElementById('list_1').style.display='none';"><a href="#" target="_blank">平面设计</a>
<ul id="list_1">
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
</ul>
</li>
</ul>
<ul>
<li onMouseOver="document.getElementById('list_2').style.display='block';" onMouseOut="document.getElementById('list_2').style.display='none';"><a href="#" target="_blank">平面设计</a>
<ul id="list_2">
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
</ul>
</li>
</ul>
<ul>
<li onMouseOver="document.getElementById('list_3').style.display='block';" onMouseOut="document.getElementById('list_3').style.display='none';"><a href="#" target="_blank">平面设计</a>
<ul id="list_3">
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
<li><a href="#" target="_blank">平面设计</a></li>
</ul>
</li>
</ul>
</div>
</body>
</html>
