在一个页面通过点不同的菜单换图的问题;

<a href=# onclick=javascript:tag(1);>菜单一</a> <a href=# onclick=javascript:tag(1);>菜单二</a> <a href=# onclick=javascript:tag(1);>菜单三</a>



<SCRIPT type=text/javascript>
function tag(id){
这中间部分如何写,如果点菜单一,那么a="img.jpg"
如点菜单二,那么a="img1.jpg";如果点菜单三,那么a="img2.jpg";
}
</SCRIPT>

我这怎么得不到呢,下面是代码:
<!--#include file="../../inc/conn.asp"-->
<%list=request("action")%>
<SCRIPT type=text/javascript>
function tag(id){
document.all.["images"].img1.src="img/img_top0"+(id)+".jpg";
}
</SCRIPT>
<link href="css/css.css" rel="stylesheet" type="text/css">
<table width="591" height="450" border="0" align="center" cellpadding="2" cellspacing="1" bgcolor="#666666">
<tr>
<td valign="top" bgcolor="#A2B19E"><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="392" height="400" valign="top" bgcolor="#FFFFFF"><table width="100%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td><img src="" id="img1" width="392" height="30" border="0" usemap="#Map" />
<map name="Map" id="Map">
<area shape="rect" coords="123,2,250,31" href="02.asp" target="list" onclick=javascript:tag(1);>
<area shape="rect" coords="249,2,392,36" href="03.asp" target="list" onclick=javascript:tag(2);>
<area shape="rect" coords="2,1,123,29" href="01.asp" target="list" onclick=javascript:tag(3);>
</map></td>
</tr>
</table>

<img src="img/img_top01.jpg" id="img1" width="392" height="30" border="0" usemap="#Map" />
原来图的路径是这样的,
http://www.ejieju.com/user/pindao/ejiejumsg1.asp这是地址,可看一下.
请帮忙,谢谢!

顶上去,大家帮忙解决一下.谢谢!

好了,谢谢islet版主!!