spltting an array (not a string)

I started writing this but then I thought, "Hey, somebody somewhere has
probably already done it!"

Can anyone point me to some Javascript that will divide an array into
two equal sizes.
(or almost)? For example, an array containing the English alphabet
would become

start = a, b, ..., m
end = n, o, ..., z

or one containing the vowels would become

start = a, e, i
end = o, u

If not, I'll finish mine and post it.

(Yes, I know it's easy, but Javascript is a brand-new language for me.)