Well, there are a lot of different implementations of Javascript. You can absolutely download the source to Google's v8 javascript engine (http://code.google.c

Well, there are a lot of different implementations of Javascript. You can absolutely download the source to Google's v8 javascript engine (http://code.google.com/p/v8/ http://code.google.com/p/v8/ ), or the implementations that Mozilla has built over the years (https://developer.mozilla.org/en/SpiderMonkey https://developer.mozilla.org/en/SpiderMonkey and http://www.mozilla.org/rhino/ http://www.mozilla.org/rhino/ ). EDIT: Yeah check the comment below regarding tracemonkey rather than spidermonkey. It should also be noted that Javascript is a specification first and foremost (unlike Ruby which is defined primarily by its reference implementation). It's worth reading through the standard: http://www.ecma-international.org/publications/standards/Ecma-262.htm http://www.ecma-international.org/publications/standards/Ecm...