Why are myarray instanceof Array and myarray.constructor === Array both false when myarray is in a frame?

Question

So the following code alerts false twice:

window.onload = function(){
                    alert(window.myframe.myarray instanceof Array);
                            


        

Answer 1

The two windows each create their own global script environment.

The Array constructor of one is not the same object as the other.

var win2=window.myframe;
alert(win2.myarray instanceof win2.Array); returns true