利用JS实现两个组合框（或者叫下拉框）的联动
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title></title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="ProgId" content="VisualStudio.HTML">
<meta name="Originator" content="Microsoft Visual Studio .NET 7.1">
</head>
<body>
<form name="doublecombo" ID="Form1">
<p>
<select name="example" size="1" onChange="redirect(this.options.selectedIndex)" ID="Select1">
<option>国外JavaScript技术网站</option>
<option>国内JavaScript技术网站</option>
<option>国外的著名搜索引擎</option>
</select>
<select name="stage2" size="1" ID="Select2">
<option value="http://wsabstract.com ">Website Abstraction</option>
<option value="http://www.dynamicdrive.com ">Dynamicdrive.com</option>
<option value="http://javascript.internet.com ">JavaScript</option>
</select>
<input type="button" name="test" value="Go!" onClick="go()" ID="Button1">
</p>
<script>
<!--
/*
Double Combo Script Credit
By Website Abstraction (www.wsabstract.com )
Over 200+ free JavaScripts here!
*/
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("Website Abstraction","http://wsabstract.com ")
group[0][1]=new Option("Dynamicdrive.com","http://www.dynamicdrive.com ")
group[0][2]=new Option("JavaScript","http://javascript.internet.com ")
group[1][0]=new Option("万旭JavaScript仓库","http://www.wanxu.com ")
group[1][1]=new Option("JavaScript2000","http://www.javascript2000.com ")
group[1][2]=new Option("无忧脚本","http://www.51js.com ")
group[2][0]=new Option("Hotbot","http://www.hotbot.com ")
group[2][1]=new Option("Infoseek","http://www.infoseek.com ")
group[2][2]=new Option("Excite","http://www.excite.com ")
group[2][3]=new Option("Lycos","http://www.lycos.com ")
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>
