Nailing object property order

Juriy Zaytsev kangax at gmail.com
Fri Apr 17 17:36:02 UTC 2015


fwiw, tests for enumeration order now in compat table —
https://github.com/kangax/compat-table/commit/a267f2233ce3b25dfbee876f4a4786ad85b31049

Results — https://kangax.github.io/compat-table/es6/#own_property_order

-- 
kangax

On Thu, Apr 16, 2015 at 8:37 PM, Brendan Eich <brendan at mozilla.org> wrote:

> Also, it's too late. Engines are converging, inter-operation pressure
> points in one direction only: greater convergence and standardization.
>
> It's true engines are not converging on the ancient insertion order, and
> that caused some interop stress, but we are over that hump now. See
> https://code.google.com/p/v8/issues/detail?id=164&can=1&q=enumeration&colspec=ID%20Type%20Status%20Priority%20Owner%20Summary%20HW%20OS%20Area%20Stars
> (a long, and long-resolved, V8 issue).
>
> Bergi's frustration is understandable. Leaving things unspecified for too
> long was a failure on our part in tending the spec, or a trade-off (we had
> other things to do ;-). All water under the bridge, but we're not stepping
> back to unspecified behavior. Because engines aren't, because developers do
> not want.
>
> And agree with Mark: POITROAE.
>
> /be
>
> Mark S. Miller wrote:
>
>> Developer productivity > hypothetical minor performance gains.
>>
>> +1 to all steps to make the specified behavior more deterministic,
>> including this one.
>>
>>
>> On Thu, Apr 16, 2015 at 10:07 AM, liorean <liorean at gmail.com <mailto:
>> liorean at gmail.com>> wrote:
>>
>>     I'm very much opposed to locking this down for general objects because
>>     it locks the implementation choices for generic objects down. What if
>>     the engine backing implementation was, say, some variation of a trie
>>     for instance? It cannot really be done today without adding extraneous
>>     data into the structure, because lookup in that case happens on a
>>     character by character basis, not on a whole string basis, so
>>     properties that use common prefixes would always end up adjacent and
>>     even if the keys weren't inserted in order by bit patterns into the
>>     trie as most implementations do, they would still be grouped by common
>>     prefix.
>>     --
>>     David "liorean" Andersson
>>     _______________________________________________
>>     es-discuss mailing list
>>     es-discuss at mozilla.org <mailto:es-discuss at mozilla.org>
>>     https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>>
>>
>> --
>>     Cheers,
>>     --MarkM
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>>
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