This is where the new Zaphod comes in. If you install it then you can run scripts using Narcissus simply by marking the web page with a special tag “application/narcissus”. You can also run scripts through Narcissus by clicking the Mozilla button at the bottom right.
Notice that Narcissus doesn't replace the SpiderMonkey engine - in fact it's SpiderMonkey that runs the Narcissus code.
What would you use Narcissus/Zaphod for?
To download Narcisus Download
Find out more about Zaphod