By "solve javascripts" do you mean view the content of a heavily js'ed/ajaxed page? In that case:

Javascript engines:

• Javascript
• JE

As for actually using javascript inside real world webpages (malformedness problems, etc), you are probably best automating a browser (Win32::IE::Mechanize, etc), but theres also WWW::Mechanize::Plugin::JavaScript

Of course you could have found all that with a super search and a quick look at cpan.