Date.prototype mutable internal properties

Allen Wirfs-Brock allen at
Wed Jul 6 12:06:22 PDT 2011

Would a better solution to simply say that Object.freeze also freeze the values of any internal properties.  If there are exceptions we can explicitly identify them for the specific built-in objects. This seems like a better solution then changing a lot of built-in properties to being accessors.

Arguably, this was an oversight in drafting ES5.

Finally, please submit work items like this to as a bug against "Draft for 6th Edition".  that way they won't get lost.


On Jul 1, 2011, at 6:01 PM, Mark S. Miller wrote:

> Thanks David,
> Yes, this is important. The way I noticed it is that the same issue came up for the FF implementation of WeakMaps <>. I will be proposing the to-be-fixed Mozilla API to the committee to become the new WeakMap proposal -- making it more consistent with Map and Set. But not at the upcoming meeting -- it's not on the agenda.
> In the meantime, <> repairs this and many other problems encountered in today's almost-ES5 implementations. Except for this issue with Date and WeakMap, all the other repairs in that file are spec non-conformances. See the kludges list at <> for cross referencing between these repairs, various bug threads, and Sputnik/test262 test names.
> On Fri, Jul 1, 2011 at 12:28 PM, David Bruant <david.bruant at> wrote:
> Hi,
> I just wanted to put on es-discuss the concern raised by Mark Miller [1]
> about mutable internal properties of Date.prototype and that it should
> be fixed in the next version of ECMAScript.
> David
> [1]
> -- 
>     Cheers,
>     --MarkM
> _______________________________________________
> es-discuss mailing list
> es-discuss at

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