Once Narcissus started getting back into shape, Tom spent the rest of his summer building Zaphod, which is now available as an experimental Mozilla Labs addon for Firefox. Zaphod lets you choose Narcissus as the scripting engine for a
<script> element by specifying the attribute
type="application/narcissus". It also lets you switch the default engine from SpiderMonkey to Narcissus so that you can run existing web pages through Narcissus.
Zaphod promises to be a great tool for getting hands-on experience with experimental JS language features. Initially, it will useful to us internally for rapidly piloting language features in the browser. Down the road, it may also become a vehicle for giving the community early access to these ideas, so they can try them out and give us feedback. And of course, it’s all open source, so anyone who wants to join in on the effort is most welcome.