People who write libraries and frameworks want to advertise them, get good SEO from the larger JS community. So they'll call their projects Blah.js. It's also

People who write libraries and frameworks want to advertise them, get good SEO from the larger JS community. So they'll call their projects Blah.js. It's also easier to remember JS libraries as Blah.js instead of having to worry that it's Blah.js or Blah.coffee. Yes it is somewhat dishonest. But users of a lib or framework should not be reading its code in most circumstances. Otherwise it's crap API/documentation. With CoffeeScript you can use the lib from JavaScript seamlessly. It is essentially Blah.js. If the lib was written in Ojb-J or ClojureScript that's another story. Then lib authors couldn't say it's Blah.js. If you need to read coffee code as JS for some reason, compile it. If you need to submit a patch, doing it in CoffeeScript will indeed be a minor inconvenience. Not so for Clojure, Obj-J or whatever else will come along. ---- And on another note. These languages compiling to JS are essentially causing fragmentation. If ClojureScript gets as popular as CoffeeScript is now it won't be pretty. I'll bet that CoffeeScript will reach critical mass at some point. The newest libs and tutorials will all be Coffee. JS.next should adopt as many features as possible or promote it as the new standard to stem the tide and make fragmentation less obvious. CoffeeScript would be more stable as a language, hard to make JS semantics prettier.