一个漂亮的互动式下拉菜单！

<script language = "javascript">
var onecount;
onecount=0;
subcat = new array();
        
subcat[0] = new array("asp基础教程","1","1");
        
subcat[1] = new array("asp web服务器iis","1","2");
        
subcat[2] = new array("asp网页设计工具fpage","1","3");
        
subcat[3] = new array("开发工具visual dev","1","4");
        
subcat[4] = new array("vbscript语言","1","5");
        
subcat[5] = new array("aspfaq","2","6");
        
subcat[6] = new array("asp组件","2","7");
        
subcat[7] = new array("asp文摘","2","8");
        
subcat[8] = new array("asp实例","2","9");
        
subcat[9] = new array("asp安全","2","10");
        
subcat[10] = new array("php教程","3","11");
        
subcat[11] = new array("phpfaq","3","12");
        
subcat[12] = new array("php文摘","3","13");
        
subcat[13] = new array("php实例","3","14");
        
subcat[14] = new array("php安全","3","15");
        
subcat[15] = new array("php工具","3","16");
        
subcat[16] = new array("数据库教程","5","17");
        
subcat[17] = new array("数据库问题","5","18");
        
subcat[18] = new array("数据库文摘","5","19");
        
subcat[19] = new array("数据库安全","5","20");
        
subcat[20] = new array("jsp教程","4","21");
        
subcat[21] = new array("jsp文摘","4","22");
        
subcat[22] = new array("jsp实例","4","23");
        
subcat[23] = new array("jsp安全","4","24");
        
subcat[24] = new array("jsp工具","4","25");
        
subcat[25] = new array("jspfaq","4","26");
        
subcat[26] = new array("精品子程序","2","27");
        
subcat[27] = new array("asp.net","2","28");
        
onecount=28;

function changelocation(locationid)
    {
    document.myform.nclassid.length = 0;

    var locationid=locationid;
    var i;
    for (i=0;i < onecount; i++)
        {
            if (subcat[i][1] == locationid)
            {
                document.myform.nclassid.options[document.myform.nclassid.length] = new option(subcat[i][0], subcat[i][2]);
            }        
        }
        
    }    
</script>
<form method="post" name="myform" action="ru_query.asp">
文章搜索：
<select name="action" size="1">
<option value="title">文章标题</option>
</select>
<select name="classid" onchange="changelocation(document.myform.classid.options[document.myform.classid.selectedindex].value)" size="1">
    <option selected value="">未指定条件</option>
        
        <option value="1">asp基础教程</option>
       
        
        <option value="2">asp技术</option>
       
        
        <option value="3">php技术</option>
       
        
        <option value="4">jsp技术</option>
       
        
        <option value="5">数据库</option>
       
        
       </select>
    
    <select name="nclassid">                   
        <option selected value="">未指定条件</option>
    </select>
<input type="text" name="keyword" class=smallinput size=10 value="关键字" maxlength="50">
<input type="submit" name="submit" value="搜索">
</form>