经测试代码如下：
<!DOCTYPE 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=gb2312 />
<title>双选择关联菜单</title>
</head>
<body>
<form name=doublecombo>
<p>
<select name=example size=1 onChange=redirect(this.options.selectedindex)>
<option>特效代码</option>
<option>网页语言</option>
<option>软件教程</option>
</select>
<select name=stage2 size=1>
<option value=/texiao/shubiao>鼠标类</option>
<option value=/texiao/chuangkou>窗口类</option>
<option value=/texiao/daohang>导航类</option>
</select>
<input type=button name=test value=Go!onClick=go()>
</p>
<script>
/**
* js 下拉框二级关联菜单
*
* @param
* @arrange (编程之家) jb51.cc
**/
<!--
var groups=document.doublecombo.example.options.length
var group=new Array(groups)
for (I=0; I<groups; I++)
group[I]=new Array()
group[0][0]=new Option(鼠标类,/texiao/shubiao)
group[0][1]=new Option(窗口类,/texiao/chuangkou)
group[0][2]=new Option(导航类,/texiao/daohang)
group[1][0]=new Option(ASP,/yuyan/asp)
group[1][1]=new Option(PHP,/yuyan/PHP)
group[1][2]=new Option(JSP,/yuyan/jsp)
group[2][0]=new Option(Dreamweaver,/ruanjian/Dreamweaver)
group[2][1]=new Option(Fireworks,/ruanjian/Fireworks)
group[2][2]=new Option(Flash,/ruanjian/Flash)
group[2][3]=new Option(Photoshop,/ruanjian/Photoshop)
var temp=document.doublecombo.stage2
function redirect(x){
for (m=temp.options.length-1;m>0;m--)
temp.options[m]=null
for (I=0;I<group[x].length;I++){
temp.options[I]=new Option(group[x][I].text,group[x][I].value)
}
temp.options[0].selected=true
}
function go(){
location=temp.options[temp.selectedindex].value
}
//-->
</script>
</form>
</body>
</html></td>
</tr>
</table>
