love the readbility but this isnt the best way

Super clever OOPified solution :)

Clever.

So, this is not the best practice even though it has 68 best practices. This mean I should not just beleive this counter, I think.

I have just joined codewars and want to understand it.

Yes, and while doing this it builds three potentially unnecessary intermediate strings.

Tell me please, does this solution iterate over formData four times?

just like my solution but with great formalization:)

I'm guessing it's because it's strictly following the principle of single responsibility. Every function does exactly one thing. But idk, doesn't look great to me.

While it was fun to figure out the one-liner, this is far more readable

it is the length of null problem. this code is not reliable

You're right, this is a bloated solution. Some people seem impressed by this kind of thing.

its valid code - but in all itterations your code "substract lives" true or false is it

No longer correct, just had an issue with that

avoid writing code with "undefined" explicit checks
plenty of alternatives available with ES6 and above