JavaScript prototype scope issue

Question

I'm new to JavaScript so I apologize if it's too dumb question.I don't understand how this keyword behaves in examples below.

In first case, this refers to window object:

Element.prototype.x = this;
some_element.x; // Returns window object.

And in second, it refers to DOM Element:

Element.prototype.x = function(){return this;};
some_element.x(); // Returns element itself.

Why? How do those examples differ?

this should help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this — BenG, Sep 25 '15 at 12:44
Or this: http://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work/3127440#3127440 — R Brill, Sep 25 '15 at 12:45

score 0 · Answer 1 · answered Sep 25 '15 at 14:26

In first case, this refers to window object:

Element.prototype.x = this; ( Here the scope points to window "Global scope in js" )

And in second, it refers to DOM Element:

Element.prototype.x = function(){return this;}; ( But where as here You are defining a function to the Object "Element", so the scope of this keyword is pointing "Element" Object. )

JavaScript prototype scope issue

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