genious! :D

I see a lot of coding solutions that are just a few lines and involve lots of complex thinking and computing that others who look at the code may struggle to understand (including me), but this isn't that complex at all in my opinion, you're simply just creating an array of letters from the alphabet, then checking if each letter is included in the input string using the every() method, I think its very efficient if anything. I think even someone using another language could probably understand whats going on since even the method names used are very intuitive.

You're right, pal. Probably most right than you think シ.

you're not alone, friend.

Yes, compared to other 7th kyu kata (which you can usually solve in under a minute) it feels more like a level 6 kata.

Creating a new array that is always three elements long and sorting it has no impact on performance. It is doubtful that you could even measure a difference.

Yes if it's not used at all. Which is definitely not in this case.