Changing [[Prototype]]

Mark S. Miller erights at
Fri Dec 28 10:55:13 PST 2012

That is exactly the issue. As long as it was not expected in IE, it
could not be assumed by the cross-browser web. However, mobile changed
MS's tradeoffs. Mobile is currently a separate enough ecosystem, with
IE a sufficiently minor player, that some cross-mobile-platform code
assumes mutable __proto__. Consider it a loss of genetic diversity on
the part of a herd that gets temporarily separated from the rest of
its species. As a result, MS is considering adding mutable __proto__
to future IE. At that point, it would become a standard, at least de
facto. In that case, we're all better off codifying a semantics and
having this standard be de jure.

If the history were different, the decision would be different.

On Fri, Dec 28, 2012 at 4:35 AM, David Bruant <bruant.d at> wrote:
> Le 28/12/2012 13:32, Anne van Kesteren a écrit :
>> On Fri, Dec 28, 2012 at 12:51 PM, Andreas Rossberg <rossberg at>
>> wrote:
>>> That's a good point, actually. I, for one, do not understand the criteria
>>> by
>>> which we chose to include __proto__ but not __defineGetter__ and friends.
>> __proto__ is in all browsers
> What? It's not in IE10 and below last I heard.
> David
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