JS触碰主栏目显示子栏目

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function butong_net(obj,name)
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 var p = obj.parentNode.getElementsByTagName("td");
 //var p = new Array(menu1,menu2,menu3,menu4,menu5);
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<style type="text/css">
.dis {display:block}
.undis {display:none}
</style>

<table border="0" cellspacing="0" cellpadding="2">
<tr>
<td align="center" id='menu1' onMouseOver="butong_net(this,'butong_net1')">
&nbsp;
<a href=Main.asp?zMenuID=1 target='_self' class='zMenuCss'>了解麦点</a>
&nbsp;
</td>
<td align="center" id='menu2' onMouseOver="butong_net(this,'butong_net1')">
&nbsp;
<a href=Main.asp?zMenuID=2 target='_self' class='zMenuCss'>麦点服务</a>
&nbsp;
</td>
</tr>
</table>

<div id="butong_net1">
<div class="undis" name="f">
<span style=" float:left">
·<a href="Main.asp?zMenuID=1&fMenuID=5" target='_self' class='fMenuCss'>麦点简介</a>&nbsp;&nbsp;
·<a href="Main.asp?zMenuID=1&fMenuID=6" target='_self' class='fMenuCss'>麦点观点</a>&nbsp;&nbsp;
·<a href="Main.asp?zMenuID=1&fMenuID=7" target='_self' class='fMenuCss'>麦点团队</a>&nbsp;&nbsp;
</span>
</div>

<div class="undis" name="f">
<span style=" float:left">
·<a href="Main.asp?zMenuID=2&fMenuID=8" target='_self' class='fMenuCss'>营销策划服务</a>&nbsp;&nbsp;
·<a href="Main.asp?zMenuID=2&fMenuID=9" target='_self' class='fMenuCss'>平面设计印刷服务</a>&nbsp;&nbsp;
·<a href="Main.asp?zMenuID=2&fMenuID=10" target='_self' class='fMenuCss'>网站建设服务</a>&nbsp;&nbsp;
·<a href="Main.asp?zMenuID=2&fMenuID=11" target='_self' class='fMenuCss'>多媒体服务</a>&nbsp;&nbsp;
</span>
</div>
</div>