Javascript function scope and object scope

Question

I got to the point where I'm trying to fill my javascript knowledge with some of the more advanced concepts.

I think I really understand how the scope works. Where objects are inherited from the prototype and then the global area, while functions offer a more traditional block area within themselves.

I have a problem with understanding:

function a(){
  console.log(this.z);
  }

a.z = 12;

a(); //returns undefined :(

I expected to repeat 12, but of course it is not. Where exactly is z stored? What does "this" mean in the example?

Answer 1

, JavaScript (this) , . , (window ) ^*.

, this , a. z . undefined.

12, ,

function a() {
    console.log(a.z);   // Use `a` itself, instead of `this`.
}

a.z = 12;

a();

^{* this undefined, - .}