Totally -- I think that 0 (which is a perfectly valid value for a number to be) bites people doing lazy initialization all the time. For this reason, CoffeeScr

Totally -- I think that 0 (which is a perfectly valid value for a number to be) bites people doing lazy initialization all the time. For this reason, CoffeeScript provides the existential operator, which asks: does this variable exist? (Is it not null or undefined?) You can use it in the same places you would use "||", as well as some others: # In place of `||` result = answer ? default # Does `object.value` exist? if object.value? # Lazy initialize the speed of the car: car.speed ?= 60 # Give me the value of `length`, only if `object` exists. length = jsonResponse.list.object?.length