Letters should only go from A to F. This goes both to upper and lower case.
It seems you are calling every possibe letter in the alphabet.

HTML colors are hexadecimal because each color goes from 0 to 256, you are only considering decimal

So you are doing s = ...
The idea is that you dont mutate the input, which will be one of the errors you will get with this while code testing. I think you would likely also timeout with the [::-1] reverse method?

The Map() method is iterating through the array.

An Arrow function is a compact alternative when writing a function

// Tradtional function
array.map(function(x){ return 'something'});

//Arrow function
array.map(x => 'something'); 

The links above will explain these concepts in more depth, hopefully this helps.

ok

Solved the problem. Thank you for reporting it.

The instructions say the first letter of each word. I believe you're checking every letter of every word.

by using .index() your code fails when there are duplicate elements in a list because it always indexes the first of those elements