Since you say that no AJAX is used, then all the info is present at the HTML source. The javascript just renders it based on user clicks. So you need to reverse engineer the way the application works, parse the html and the javascript code and extract the useful information. It is strictly business of text parsing - you shouldn't deal with running javascript and producing a new DOM. This would be much more difficult to do.
If AJAX was used, your job would be easier. You could easily find out how the AJAX services work (probably by receiving JSON and XML) and extract the information.
