it is a library of JS

reducer can take up to 4 arguments, you can just omit the last two, which are indices and array. So you can use acc and value of the index.

I have done this first. Need to do cycle, but need more time. No time for now.

poor explanation to the good task.

I thought the 3 answers were auto tested, but no, it is just copy paste from the line you get.
I mark unclear explanation in the task.

Secondly, if you dont knowe reg ex then you will spend more time on this. According to the methodoly
this is not the good move, you need to explain first and then give the task but not just mention
that it will be difficult for beginners. Spent much time there.

One big mark: you dont just move 3 letters back in the alphabet, you still have
to consider all the symbols and numbers that should not be moved 3 symbols back.

One helpet: you should use Unicode table to see which num is the symbol.

Good luck.

Just copy and paste the answers when you get them

This is the only solution without regex. I have spent some time on it. I took me a while without knowing the reg expressions. You have got better code.

And the explanation to the task with the three answers was unclear.

clear code. I like

My "sandwich" is longer. Shorter code is smarter code. Good job.

I have got the same approach but I divided every action in a different line. This way more readable for me. I failed to make a sandwich like you did, still need to train.

It is good to have everything in one line. Saves code space. Good job.

wanted to do switch, but failed to think about Number values in CASES

I thought the obj was not defined by default and wrote the definition of the obj separately. Worked.