To anyone interested,
I just developed a (free&open source) library to type check arguments and return values of functions, and permit the use of some sort of "interfaces", ala Java.
I think it might be useful for those developing larger JS projects (esp. if you write unit tests). I'd really like some feedback from those interested. Would it be useful? Do you like the syntax? What could be improved?
Here's the site/doc I created for it: http://www.fsavard.com/code/fsignatures/
You can email me directly (francois at fsavard . com), PM me or reply here, as suits you.