> And JS has some incredible flexibility, with CoffeeScript (CS after) you can even get a more terse syntax similar to ruby/python.
CoffeeScript isn't JS, its a different language that compiles to JS. So what CS can do doesn't say anything about JS as a development language.
> You will not be able to use Ruby or C++ in client-side browser code any time soon.
You can use C++ in client-side browser code now -- sure, you compile it to JS, just as you compile it to native binaries to run on the server side, but the development language can be C++. [1]
CoffeeScript isn't JS, its a different language that compiles to JS. So what CS can do doesn't say anything about JS as a development language.
> You will not be able to use Ruby or C++ in client-side browser code any time soon.
You can use C++ in client-side browser code now -- sure, you compile it to JS, just as you compile it to native binaries to run on the server side, but the development language can be C++. [1]
[1] https://github.com/kripken/emscripten/wiki