CoffeeScript's existential operator
I was perusing CoffeeScript’s documentation when I found a bit I’d overlooked: it’s got an existential operator. The existential operator that allows you to access a variable but only if it exists. Without it, you’d write code like this:
if player and player.hat?
hatColor = player.hat.color
else
hatColor = undefined
With CoffeeScript’s existential operator, you can avoid that.
hatColor = player?.hat?.color
This can shorten your code by a fair bit.