Great! You can also use this idea to create proxy/decorator, immutable structures.

Cool. Actually Object.defineProperty is preferred in modern code, but anyway kudos for self-learning.

With bind you don't need to declare additional self variable.

Default function is cool. Not sure, why do you need to sort anything.

Thank you, Kirill. Indeed, it's much more elegant. I've saved it as well amoung my imperfect solutions ... just for memorizing.

You can use [].concat.apply([], arguments) if you'd like to concat arbitrary amount of arguments.