[past]

Besides being an incredibly powerful combination of a functional and an object-oriented language, I just adore the fast redeployment cycle during development. With appenginejs, I test every change in the backend code by simply refreshing my browser. Not jaw-droppping per se, but certainly a breath of fresh air for a long-time "enterprise" Java developer, like me.

[sreque]

Javascript's functional powers are equivalent to or worse than every other popular dynamic language in existence. Speaking of functions, I prefer not to do argument arity checking on every single function I write(I'm looking at you too, perl!), or accidentally assigning global variables through a simple misspelling. I also really hate it if I accidentally invoke a function on a primitive and it silenty fails by returning null. Use 'use strict', you say? How's the implementation of that feature coming these days? I know firefox still doesn't have it. Does v8 yet?

From what I've read, other Prototype-based languages treat Javascript as their ugly step cousin, and I would overall consider it a much inferior OO system to that found in Python, Ruby, CLOS, Perl's Moose, and PLT-Scheme, to name a few.

You can easily get rapid redeployment in any dynamic language. You can even get it on the JVM with Java, as the Play framework is showing us. See http://www.playframework.org/.

If Javascript is your first dynamic language after developing in Java for X years you might think it is neat, but it is really far behind just about every other language out there it directly competes with on the server-side level. It was never designed to be a scalable general purpose programming language and the latest incarnation is still far from reaching that lofty goal.