Finding the Object Origin URL

The object origin is always defined by its static scope. That is, global objects always derive their origin from the origin of their document. Similarly, an object local to a function or method derives its origin from the origin of the method. A reference to a variable x in a document d loaded into window w is really w.x and thus derives its object origin from the origin of d. Let y be a local variable to the function foo(), located in a document d in window w. Even when foo() is called from a different window otherWin, e.g., when ``z = w.foo();'' is a line in otherWin, the object origin of y is still determined by its static scope, the origin of d. Note that in ``otherWin.location = "javascript: x = 1;"; ``, the ``"javascript: x = 1;'' part is just a string and not code; thus the static scope of x is within the window otherWin.

Dynamically created documents (e.g., created by document.write) should always inherit origin from the creating window/document.

Here are some examples for code executing in a window w1, loaded from origin o1:

v = foo(x);
  // o1 remains subject origin 
  // for function ``foo''
v = w2.foo(x);
  // o1 remains subject origin 
  // for function ``foo''
  // foo will execute in w2's scope
w2.location = "javascript:foo()";  
  // o1 remains subject origin 
  // for function ``foo''
  // foo will execute within a 
  // top-level stack frame 
  // of a new document in w2.
w1.document.write(foo()); 
  // o1 remains subject origin for 
  // function ``foo''
  // foo will execute in a new 
  // document in w1, whose origin  
  // is the same as the one of 
  // the current document
w2.eval(w1.foo(x)); 
  // subject of this statement is o1 and 
  // thus is subject of foo. 
  // foo will execute in w2's context, 
  // since w2 owns the eval method.

Thus, in this context, the object origin can always be retrieved in one step, by accessing the enclosing scope.