Regarding the Coffeescript-Javascript difference, Coffeescript and Javascript can be used transparently in node. Once require('coffee-script') is run, the module replaces the require function with one that can load both Coffeescript and Javascript.
This means that if there is a file ./lib/foo.coffee, the following code in bar.js will work:
require('coffee-script');
var foo = require('./lib/foo');
Yes, some people may not like Coffeescript anywhere in their project, but this functionality makes it easy to add Coffeescript to an existing Javascript project or use Coffeescript modules as a blackbox in a Javascript project.
That's pretty cool. I didn't know that worked so seemlessly.
Nonetheless, in order to use a library, you must either read the documentation or the source. The biggest issue is that most CoffeeScript projects document with CoffeeScript. Technically, you could read the compiled source, but that's usually a non-starter unless I truly need your project. Otherwise, I'm more likely to find someone else that's solved the same problem, but has written their docs / source in JavaScript.
This means that if there is a file ./lib/foo.coffee, the following code in bar.js will work:
Yes, some people may not like Coffeescript anywhere in their project, but this functionality makes it easy to add Coffeescript to an existing Javascript project or use Coffeescript modules as a blackbox in a Javascript project.