Why that question mark for?

Question

i got confused when these all codes were easy and this big code comes up.

Answer 1

You didn't post the code. But if I guess it right maybe you mean ternary operator. If the result before "?" is true it returns the value after "?" if it is false it returns the value after ":". You can read more here (JS use) https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator