Oh, you're right! Apologies

You just linked the general solution page. I think you wanted to link your solution instead.

Your solution includes multiple loops, just not by yourself but by called functions. includes(), indexOf(), slice() and string concatenation all loop over the strings again and again and also create new string objects every time. Since you call them in a loop your solution is O(n²) while this solution loops over each string exactly once and once over the stack, which contains at most 26 elements.

Faster, less memory solution: https://www.codewars.com/kata/5b1b27c8f60e99a467000041/solutions

uses one loop, no objects.

yeah, that's a good point.
I've started to comment my code and even leave in console.logs.
The reason I left them out was to get the code as succinct as possible, but that's just for pride.

way too complicated for the top answer to this tricky kata! I'm pretty proud of mine.

.

Read this: https://docs.codewars.com/training/troubleshooting#print-input

Hi, I'm passing all basic tests and 191 random tests, but I have no idea why I'm failing the others. Can anybody give me a clue ?

Update to Scala 3

Leave it, maybe it helps someone.

Oh right, my bad... even before that block there's this:

Your task is to return the first longest string consisting of k consecutive strings taken in the array.

Should I delete this thread?

Your task is to return the first longest string

Two strings are the longest: "folingtrashy" and "abcdefuvwxyz".
The first that came is "folingtrashy" so 
longest_consec(strarr, 2) should return "folingtrashy".

It's explained in the description.