How To Give An ID Value From Tha Directory Name?

I shoud give a "value" to an DIV's ID that change following the name of the
directory where the file is.

For example the file is here:
www.website.com/web/01/file.html

Is it possible with javascript to give the value "01" to the DIV's ID?
<div id="namedirectory"something inside </div>
so it could be readed as:
<div id="01"something inside </div>

I found in internet this one:

<script language="JavaScript">
fullpath=location.pathname;
document.write(fullpath);
document.write('<br />');
result=fullpath.split("");
document.write(result[5]);
</script>

it's something that could work?
I don't know how to recall the value in the ID...