分两个等级的下拉菜单
要完成此效果把如下代码加入到<body>区域中
<FORM name=doublecombo>
<P align=center><SELECT name=example
onchange=redirect(this.options.selectedIndex) size=1>
<option>总类一</option>
<option>总类二</option>
<option>总类三</option>
</SELECT> <SELECT name=stage2 size=1>
<option value="link.htm">分类一</option>
<option value="link.htm">分类二</option>
<option value="link.htm">分类三</option>
<option value="link.htm">分类四</option>
</SELECT> <INPUT name=test onclick=go() type=button value=Go!></P>
<SCRIPT language=JavaScript>
<!--
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("分类一","#")
group[0][1]=new Option("分类二","#")
group[0][2]=new Option("分类三","#")
group[0][3]=new Option("分类四","#")
group[1][0]=new Option("分类一","#")
group[1][1]=new Option("分类二","#")
group[1][2]=new Option("分类三","#")
group[2][0]=new Option("分类一","#")
group[2][1]=new Option("分类二","#")
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>