Why downvote?, Coffeescript is not even a language.
Programmers who use this crap must suffer.
Software development is not a war, please please stop treating it like this. We are all in this together. Insulting people because they choose different tools hurts everyone.
Sort of. And then you get the job to maintain the transpiler-of-the-day code that some previous employee left behind.
I seriously doubt the 10x number, as it's just some syntactic sugar, and not that advanced at that, and comes with its own issues.
Actually, I (and Fred Brooks, in "No Silver Bullet") don't think there's any technology that added to some programming language will make you 10x more productive.
Maybe having an editor compared to writing to punch cards.
JS seems small enough that you shouldn't have many problems in this matter, but there's usually some warts
Coffeescript is just coffeescript so there really aren't any incompatibilities.
The only gotcha that I've hit a few times was the automatic returns that are inserted. Sometimes you have a chain of functions that requires a true to be returned from a function and if you don't do it explicitly, coffeescript will return a falsy value.
The JS it generates is a tad ugly, but you save way more time, clarity and readability than with vanilla JS.
It appears to be cleaner and sometimes more expressive than JavaScript in some ways. That's not worth Holy-warring against.