It seems like you are seeing some old version code, that is the most likely thing I could come up with. (Try clicking reset to see the newer version) Otherwise, JS is already updated to latest version and so is the description, closing!

solution is simple, but bad perfomance as well as with map() instead of .find().

unary plus... good)))

there is mistake still. As task we have function sumStrings(a, b) {}, but in tests it has been using sumStr(a, b) !!!

I mean it is simple and clever, but in a big teams sometimes happens that other coders could read such short expressins wrong. misunderstanding. for example here if you use parseInt(inputString[0]) it would be more visual recognisable according to task discription.

Apologies, but can you please explain what is difficult to understand?

Very clever, but such disisions are difficult for understanding by others if you work in a big team...human factor is coming)

that's Okey) just a small correction)

lol. I also completley forgot about that. I guess the test cases ignored that. but you could still implement it