Separating the comparison so far from the rest of the ternary operator isn't very readable. I wouldn't consider this best practices.

I agree, and additionally, the wording of the kata is so unclear that if I didn't already know what reduce does, I would have had no idea what the problem is actually supposed to be.

This leads me to wonder if a better answer would also break words separated by &nbsp

I personally think this should be the top answer. It offers flexibility, readability, conciseness, and it maintains encoding independance.

I would recommend against encoding-specific solutions for any portable language, but especially for JS.

We want to keep trying until we reach the end case, where we have a single digit. We use recursion to make that happen.

Today I learned JS doesn't terminate the variables declared in for loops if you use var

While undoubtedly clever, I don't get why this has votes for best practice. As a and b get farther apart, the stack gets unnecessarily large.

The description is confusing. They simply want you to provide the name of the winner, not the whole dialogue they provide in the description. The winner is the one still alive after one fighter's health is zero or less. The fighters take turns attacking each other.

Wouldn't for .. of be functionally identical (And slightly easier to read)?

Gosh this website teaches me something new every kata. So succinct.

Thank you for linking to documentation in your comments! This is elegant, clearly indicating what you are operating over, and overall very good programming :)