In case you were already familiar with Narcissus, this appears to just be Narcissus packaged in a Firefox addon, not a new JavaScript implementation written in JavaScript as the title implies.
You're correct. To me, JavaScript in JavaScript that can run in the browser was the most important part (although I should have added "in the browser"). If I had called it "Zaphod - run Narcissus in firefox", it probably wouldn't have gotten anyone's attention.