The instructions are a bit lacking, yes. But some of the katas are partly (or wholly) about figuring out what to do.

About the messy code, I agree with you if you're referring to this particular solution. It's not very good style to declare some member functions inside of the constructor and some outside on the prototype object. Only inside or outside is better, but if you want to keep the name property "private" you need to use the "inside" method.

I like this Kata. Pretty simple, at first I thought it was some complex issue but it wasn't, seems to be a thing with codewars. Lets people spot code bugs in a simple way.

Instructions for this Kata weren't really all that clear. The code is a bit messy in my opinion.