Suggestion:

You must return the index of the word which realizes the highest score. Ties are decided by length. If two or more words have the highest score, then the index of the shortest word should be returned.

Your current solution appears to consider word length, but I have added some more edge cases that should prevent solutions which do not from passing.

CoffeeScript translation

Scala translation

Please review the test cases. My solution randomly passed, not considering the shortest word.

Really good Kata. Clear rules.
Thank you!

Amazing solution to learn how to apply multiple conditions in one regex. Respect.

Nice Kata. Many opportunities to try language features.

Wow. Doing all with bit operations instead of strings. Really nice == clever.

Nice solution. We can skip the +1 as the last number is always in the array.
(I saw this in another solution ... and yes, it made total sense.)

Smart solution. I did not think of this ... I am still too fast on "pythonic" code, using it's language features rather than find a near optimal solution.

Yes, one can skip the +1. Well done.

Easy to read. Nice logic.

You know, a sauna sounds like an underrated problem solving tool