"Instance properties" are not actually in the instance #80
Description
In chapter 3 you are introducing instance properties. The syntax you are using is, in my opinion, not generating a instance property. The value is saved in the prototype of the class and not in this. Additionally, if you initialize with an object the object will be shared between all instances and changes on it will apply to all instances.
I would recommend initializing an instance property in the constructor.
Please fix this as you are having a high google rank on a search for 'coffeescript property'.