love the readbility but this isnt the best way

Nice.

For this case it won't make a difference since we do not have any block within the function.

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?

I learned algebra with yoru solution

Any one here can explain me I didnot understand this! I am not good in Math

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

Very good readability +1

Only note is 'var' is now 'let'

I agree with you, but it's just not in the "clever" category.

%1 soooooo smart :)