As you suggest, there are several schools of thought about how best to provide class-style programming. By using a closure instead of prototypes, you can have "true" private properties and functions. If you use prototype, you'll need to use a convention to mark something as private and hope the developers respect that (marking it with an underscore is common). In my experience, someone will ignore the convention and then something will break when you change or remove your "private" variable.

Thanks.

> Instead of using prototypes and functions shared among all instances of the same type of object, it uses closures for each instance.

So, is this generally considered a poor practice? I usually only use prototypes and shared functions when I am going to be instantiating the same type of object many times (when doing lots of vector math, for example).