ball_type is a method, not a property.

Also, OP solved it, closing

If a compiler / interpreter does TCO, a recursive implementation can be asympotically just as fast and just as small as an iterative implementation.

If you're judging this purely on raw speed, you haven't understood the concept of "Best Practice" anyway.

Duplicate issue.

Fixed

you don't technically need the parenthasis either when you have no argument to pass. so title.capitalize.split.map would be just as operational here.

It expects string undefined rather than actual undefined (see the quotes around the expected undefined).

Not if you use trampolining or lazy evaluation. But well, those are pretty advanced techniques.

You're right. I was thinking in 2%0. It's useless.

0 can be divided by any numbers so I don't think "number + 2" would do anything useful here.

It is the same as split(" ") and split

Hi, it could be an infinitive loop, try to debug it. Does it occur for each tested string?

Expected: undefined, instead got: undefined

seriously?