How is this clever at all? I must be a genius, then.

The is what psychopathy looks like.

My solution was to actually compute the lookup table and cache it.
I was about to ask on a forumn if what I did was cheating, until I saw this.

Your code has actually 4 lines. Not that it matters, though.

How can two persons think of the exact same solution.

function isDefined(value) {
  return !isUndefined(value)
}

That is just beautiful. It inspired me to write this program:

function isNumberOne(number) {
  return isAnInteger(number)
    && isSmallerThanNumberTwo(number)
    && isBiggerThanNumberZero(number);
}

dat cool

Saying "this is how you'd want to write" is like apologizing for bad/long code. This is a coding competition, afterall.
Check out my solution and see how it's done.

Great solution, but the second replace is not necessary.

It filters the array twice; nonetheless, it takes 1 millisecond to run.
Where is your god now?

He just used google.