The first thing I can mention is that editing a javascript tiddler doesn't affect the running javascript until you save the tiddler _and_ reload the page. The other thing I'd do is mention the web developer tools. IF when viewing the wiki, you hit F12, it should open the web developer tools. Under the sources tab, under "No Domain" in the left hand side, you should see all the javascript files from your wiki loaded. You can view individual files, and if you click on a line number, you can pause execution next time that line is executed and you can look at the contents of the variables.
Hope that helps.
Matt