Javascript static vs instance, prototype keyword

Question

I want to know the difference between the following two code snippets

What I understand is this is static because without creating an instance with new keyword, getC

Answer 1

Further details

@jfriend00 has already given a very helpful details on how JavaScript treats object. Let me add some details about the difference of this keywords in both cases:

Static case

If you define a static function through an object's property, the this keyword in the function refers to function scope, not the parent object.

See example:

var F = function(){ this.a = 500; };
F.G = function(){ return this.a; };

// call it
F.G(); // returns undefined, because `this` refers to F.G()
       // but the variable a in F.G() has not been defined yet

Prototype case

If you define a function through object's prototype, the this keyword in the function refers to the instance of object you create from that prototype, not the function scope.

See example:

var F = function(){ this.a = 500; };
F.prototype.G = function(){ return this.a };

// Make an object and call the function
var f = new F();
f.G(); // returns 500 because `this` refers to instance f