Sets and Maps are deterministically ordered by insertion order.
On Tue, Dec 31, 2013 at 1:53 PM, Brendan Eich <[email protected]> wrote: > David Bruant wrote: > >> Hi, >> >> I've been playing with Sets recently and believe that the following >> additions would make them more useful by default: >> * Set.prototype.map >> * Set.prototype.filter >> * Set.prototype.toJSON = function(){ >> return [...this]; >> }; >> >> The 2 first are to easily create sets from existing sets very much like >> what we already have with arrays. >> > > These seem good. > > > I haven't had a use for a .reduce yet, but maybe that would make sense >> too? >> > > Are Sets ordered just because for-of says so? :-P > > When in doubt, leave it out. > > > The toJSON is just to provide a good default. Obviously anyone >> disatisfied with it can shadow it on specific instances. But this >> serialization makes more sense by default than the one you get now (own >> properties of the set object... which have none in common usages?) >> >> Hopefully both IE11 and Firefox having shipped Sets without this toJSON >> behavior won't prevent this change? >> > > No draft-spec implementation can foreclose further spec additions to a > built-in prototype, in the draft spec as it evolves at any rate. Yes, > Array.prototype.values bit us, but via 'with' (of course -- the one you > should most suspect!). Not here, though. > > /be > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > -- Cheers, --MarkM
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