I can't even get rollover images, which are standard on many sites!  If you
know of mirroring software that parses JavaScript as effectively as you
propose, I would like to know about it!  It would save me a lot of work:  I
use Firefox (because it's much better than IE/Netscape, and free), but it has
a tricky cache - more secure - which does not allow easy extraction of
graphics.  So I have to view the "rollovers" in IE, then yank them from its
cache - not fun, but better than nothing.

I find commercial (i.e., costly) mirroring software is usually much worse than
HTTracker, whether in terms of javascript or overall efficiency, as well as
functionality (e.g., fewer options).