Oh, thank you very much. I finally saw what the problem was.
Yes, i used the exactly examples from the 'sample tests'.
But i accidentally deleted the empty line, when i was copying the strings. And that's why everything was ok in my IDE.
After your comment i've changed my code and it works now. And it's even shorter.
Thank you again!

The problem is - i don't understand why i get TypeError: item.join is not a function. But in my IDE i do not get such an error. As you understand if the code has an error it has it everywhere - both in IDE or in Codewars.
Then there is a problem in something else, but not in the code.

I'll try to explain widely.
In my code i use such a method as join().
My code works correctly in VS Code. I receive required results.
But here, when i push TEST button i get - TypeError: item.join is not a function.
If i push ATTEMPT button i got the same error in the basic tests, but i can also see my code passed the random test.
I hope my explanation is more clearly now)

Can anyone help please! My code passed the random test, and in my IDE it works correctly too.
But in the basic test i've got - TypeError: item.join is not a function.

The hardest thing in this kata is its description. It's unclear.
Gentlemen, please, when you make your katas, be merciful. Don't make users feel confusing.

I don't want to look rude, but...
It was a really annoying kata.
It doesn't teach of anything, just wasted your time on little things

Thanks a lot!

I fully agree with you. I thought the same, when i was resolving this task. And i think the most part of programmers thought the same.

Спасибо! Благодаря вашей подсказке решил задание. Хотя, наверное, как и большинство, сначала делал через extends.

The author's explanation is really unclear.
Guys, attentively read the name of this kata and you will understand what you need to do!
You need to find the maximum difference between strings' lengths of array one and array two.

Thanks for your comment, sir.
It helped me to resolve this task.
The author's explanation is really unclear.
Guys, attentively read the name of this kata and you will understand what you need to do!

Thank you very much, sir. You are right. I have changed Node version and my code passed all the tests. I didn't pay attention to it before. Thanks again.

Hi! I got some strange error. In my function i used method of string "str.at()". And in console everything is OK, i got correct results in all cases (i took your examples). But when i tried to test my decision here, i got this error "TypeError: item.at is not a function". Can you tell me please, what is wrong.
If you need my decision for checking i can provide it.