Finiteness of object properties set

Brendan Eich brendan at
Wed Sep 7 09:43:41 PDT 2011

On Sep 7, 2011, at 6:12 AM, Tom Van Cutsem wrote:

> 2011/9/7 David Bruant <david.bruant at>
> Le 06/09/2011 17:59, Mark S. Miller a écrit :
> I agree that the spec should clearly state that a non-extensible object has a finite collection of own properties. Regarding infinite extensible objects, the only problem I see off the top of my head is: What would Object.getOwnPropertyNames return?
> And what about for-in loops? :-p
> It's always possible to break/return early, no? Didn't iterators/generators already cross this bridge? An iterator could iterate over an infinite stream of values.

Indeed the derived iterate trap supports infinite objects -- this was a use-case Waldemar raised this at TC39 meetings last year, IIRC at the November 2010 meeting (notes posted to es-discuss).

See also


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