.js文件问题

[glassfish1]

各位好：请问.js文件有什么用处？global.asa文件又有什么用处啊？请给出详细的回答，谢谢！
另外再帮我看看下面这段程序:重点是问号的部分.
<script language = "JavaScript">
var onecount;
onecount=0;
subcat = new Array();
<%
count = 0
do while not rs.eof
%>
subcat[<%=count%>] = new Array("<%= trim(rs("Nclass"))%>","<%= trim(rs("classid"))%>","<%= trim(rs("Nclassid"))%>"); ????????是创建几维的数组?
<%
count = count + 1
rs.movenext
loop
rs.close
%>
onecount=<%=count%>; ???????

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>
<script src=ubbcode.js></script>

[若白师妹]

下拉菜单联动

[任亚军]

直接写在页面里也可以,不过为了方便,放在一个文件里了