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Perhaps the author meant for those who know Ruby: - @ for instance variables - #{} interpolation and Python: - for comprehensions - significant whitespace
Those are syntactic sugar. If your devs have trouble understanding JavaScript because of this, I suggest your devs aren't very good.
When I first saw them I just asked jashkenas in #coffeescript and then it made sense. Later I came to appreciate them in Python. Coincidentally I learned Ruby-style string interpolation from CoffeeScript before trying Ruby.