26973 2014-10-05 00:57:58 +0000 make iterable declarations' iterator prototype objects inherit from %IteratorPrototype% 2016-09-08 21:12:08 +0000 1 1 1 Unclassified WebAppsWG WebIDL unspecified PC Linux RESOLVED FIXED P2 normal --- 1 cam cam allen brendan bzbarsky d dherman mike public-script-coord public-webapps-bugzilla oldest_to_newest 112703 0 cam 2014-10-05 00:57:58 +0000 http://heycam.github.io/webidl/#es-iterator-prototype-object [[ The internal [[Prototype]] property of an iterator prototype object MUST be the Object.prototype object. ]] http://lists.w3.org/Archives/Public/public-script-coord/2014OctDec/0058.html points out that iterator objects in ES6 all inhert from %IteratorPrototype%, so we should do the same with iterator prototype objects generated for iterable declarations. 112704 1 brendan 2014-10-05 02:43:26 +0000 The plan is to put much-wanted methods on Iterator.prototype, in ES7. The iteration protocol in JS is still structural, but Iterator() provides an adapter from structural to nominal, with map/filter/etc. handy methods via prototypal inheritance. Dave should correct me on anything amiss here. I hope this helps improve the web platform sooner. /be 112707 2 bzbarsky 2014-10-05 03:30:18 +0000 Yeah, having generic map/filter that apply to any iterable and live on Iterator.prototype (and perhaps some prototypes of other iterables like Set and Map) would be really nice! 112711 3 brendan 2014-10-05 05:03:33 +0000 (In reply to Boris Zbarsky from comment #2) > Yeah, having generic map/filter that apply to any iterable and live on > Iterator.prototype (and perhaps some prototypes of other iterables like Set > and Map) would be really nice! Iterator not iterable, so if Map and Set have standard iterators that delegate to Iterator.prototype, then everything works automagically. You name a map or set on the right of for-of's 'of' and @@iterator does the rest. Having Map.prototype.map do the @@iterator call and delegate to the returned iterator's map is doable but seems unnecessary when using for-of. When calling someMap.filter directly, of course, it's wanted. Some design freedom here to "do both", IMHO. /be 112712 4 cam 2014-10-05 05:16:51 +0000 This would mean that you would write things like: myMap.keys().filter((x) => x > 10) yeah? To make it a little easier to type than: [...myMap.keys()].filter((x) => x > 10) 112720 5 brendan 2014-10-05 16:21:14 +0000 (In reply to Cameron McCormack from comment #4) > This would mean that you would write things like: > > myMap.keys().filter((x) => x > 10) > > yeah? To make it a little easier to type than: > > [...myMap.keys()].filter((x) => x > 10) Yes, and more efficient too. (BTW the single-parameter arrow function form does not need parens around the formal parameter: x => x > 10 -- just passing this along in case it needs some publicity. ;-) /be 127350 6 d 2016-09-08 21:12:08 +0000 This appears to have been fixed a while ago.