[Bug 8241] Named properties on window


Brendan Eich <brendan@mozilla.org> changed:

           What    |Removed                     |Added
                 CC|                            |brendan@mozilla.org

--- Comment #12 from Brendan Eich <brendan@mozilla.org> 2011-06-20 05:18:52 UTC ---
(In reply to comment #11)
> In the Firefox, case at least, I think part of your problem is that you're
> lumping together _different_ sorts of named properties.  In particular frame
> names are treated quite differently from properties that come from the global
> scope polluter in Gecko; I can't speak to other browsers.
> The exact Gecko name resolution process on Window is:
> 1)  Something with standard classes (Object, Array, etc).  Not quite sure what
>     and how those interact with named frames and the like.
> 2)  Look for a named frame with that name.

This is a decision tree (skinny, one path only, so a list). Since (2) comes
after (1) we can be sure that buitl-ins (standard classes such as Object) are
resolved in preference to frames of the same name. Of course frame indexes
cannot name any built-in in ECMA-262, so those are resolved in a step (0).

Also, there is a step (1.5) where 'constructor' is handled specially, so that a
frame with that name cannot shadow the prototype property of that name on
Window. I'm not sure this is anything but a historical accident, though.

Re: comment 10: it is important for integrity and optimizability that
var-defined bindings be non-configurable.


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Received on Monday, 20 June 2011 05:18:59 UTC