Yeah, especially because Coffeescript can be very liberal with creating objects if you don't know exactly what you (and coffeescript) are doing.

edit: Disclaimer: I have written and am still occasionally writing canvas rendering stuff in coffeescript and after some meddling around with some annoying bits it has been quite pleasant. For example you should make sure that functions that don't need to return anything, return false or null or undefined. Otherwise coffeescript will return whatever your last statement evaluates to. This is especially bad if the last thing is a loop.