HTML chunks: How to write filenames?

I need to create a dropdown box in a HTML page (a chapter) which can be  
used to jump to another chapter. In order to populate the dropdown box I  
need to know the chapter titles and filenames. The handwritten Javascript  
looks like this:

var titles = new Array('Title', 'Chapter 1', 'Chapter 2');
var filenames = new Array('title.html', 'introduction.html',  
'somethingelse.html');
create_toc_dropdown(titles, filenames);

While I think I can manage to write the chapter titles I don't know where  
I get the filenames from (I use HTML chunks). If for example the first  
chapter is written to a HTML page is the filename of the second chapter  
already known?

Thanks in advance,
Boris