It was a few months ago, but I recall successfully using HTTP::Recorder to use HTTP::Proxy with JavaScript enabled sites. HTTP::Proxy traps all HTTP requests, regardless of whether they are plain HTML hyperlinks or initiated by JavaScript. Granted, this only works when JavaScript does something simple, but in my experience it usually does. If the JavaScript does anything complex, then you're right: you'll have to either run a JavaScript interpreter within Perl or rewrite the algorithm in Perl.