Ok, I understand that but how is "even" or "odd" determined based on the reducer returning 0 or 1?
I understand that 0 is the first element of the even,odd array and 1 is the second element, but how is the value passed in? I apologize if my phrasing is poor, I'm trying to learn ES6 right now.

How exactly does this work ? I understand the reducer section, but how does this arrow function interact with ["even, odd"]?