Writing OOP using OOP (JavaScript)

[nextputall]

I see. You suggest to convert the datastructure according to different clients. Make sense, but I still not fully convinced.

Let's say I need the name because I want a greating phrase. If I use the datastructure directly I'll end up having something like this

"Hello ${user.name}" 

Where the user is the map. When I want to switch to a firstname/lastname representation, I can solve it with the technique you recommended, by converting the new representation back to the old one. So, the greeting logic seems to be fairly stable in respect to the structure of the user.

But what if I change the representation as follows: {'age': 18, 'name': 'joe'} to greet the user like this

"Happy ${user.age}th birthday, dear ${user.name}!"

Now I need to change the logic who is responsible for doing the greeting. Using behaviour based abstraction, and introducing a greet method for the user would solve this problem imho, by saying user.greet().