[lowboy]

That's not to say that packages aren't being written in CoffeeScript as source and then being compiled to Javascript for distribution. That wouldn't require CoffeeScript to be in the deps at all if a dev doesn't use build tools (gulp-coffee, browserify+coffeeify, etc).

[joshfinnie]

I agree, I would be interested to see how many packages are written in CoffeeScript but then compiled for NPM or the open source community.

It is interesting to get people who will not support your project if it's CoffeeScript... I would think this is the driving force and not so much that CoffeeScript is not popular.

[lowboy]

Agreed, which is too bad. It's one thing to not contribute to a project if the source isn't to your liking, but it's another to flat out not use the compiled version.

Besides, I've found that writing CoffeeScript is pretty much like writing Javascript. Different syntax, but the semantics are almost entirely 1:1, leaving out the class stuff (which I don't often use). I've introduced CS to many JS devs and while not all of them loved it, they were able to get up to speed very quickly. But I understand peoples' objections to it - I think they're wrong, but I understand them!

[phadej]

Good comment!

I did make a too quick judgement there. It turns out you can't easily see how popularality of CoffeeScript has changed.

    It is surprising to see CoffeeScript in this list as a language compiler
    should be mainly a dev-dependency. You compile the CoffeeScript source to
    JavaScript for distribution, so you don’t need coffee-script to be a
    dependency. The packages that depend upon coffee-script include among others:
    grunt, jasmine-node, jscoverage, cucumber and hubot. They all allow you to use
    CoffeeScript sources.

While there isn't anything wrong in supporting CoffeeScript out-of-the-box, I like karma's approach more. It has "karma-coffee-preprocessor", it should be self-explanatory.