> No engine has implemented subclassing of `Array`, yet: > http://kangax.github.io/compat-table/es6/#Array_is_subclassable > <http://kangax.github.io/compat-table/es6/#Array_is_subclassable>
https://github.com/v8/v8-git-mirror/blob/master/test/mjsunit/harmony/classes-subclass-arrays.js <https://github.com/v8/v8-git-mirror/blob/master/test/mjsunit/harmony/classes-subclass-arrays.js> Not staged yet, but it is implemented and is very cool. few small pieces missing still > On Apr 10, 2015, at 10:29 PM, Axel Rauschmayer <[email protected]> wrote: > > No engine has implemented subclassing of `Array`, yet: > http://kangax.github.io/compat-table/es6/#Array_is_subclassable > <http://kangax.github.io/compat-table/es6/#Array_is_subclassable> > > And, as Sebastian mentioned, you can’t transpile it, because it depends on > the cooperation of `Array`: it becomes the base constructor and allocates an > exotic array instance (with special handling for `length` etc.) whose > prototype is `new.target`. > > Axel > > >> On 11 Apr 2015, at 03:57, Garrett Smith <[email protected] >> <mailto:[email protected]>> wrote: >> >> On 4/10/15, Axel Rauschmayer <[email protected] <mailto:[email protected]>> >> wrote: >>> The reason why you need to call the super-constructor from a derived class >>> constructor is due to where ES6 allocates instances - they are allocated >>> by/in the base class (this is necessary so that constructors can be >>> subclassed that have exotic instances, e.g. `Array`): >>> >> Can you please explain how extending Array works. Also what is the >> optional identifier optional for in ClassExpression: >> >> var myArray = (new class B extends Array { >> constructor() { >> super(1,2,3,4,5); >> } >> }); >> alert(myArray.length); // it's 0 in Babel. >> >> -- >> Garrett >> @xkit >> ChordCycles.com <http://chordcycles.com/> >> garretts.github.io >> personx.tumblr.com > > -- > Dr. Axel Rauschmayer > [email protected] <mailto:[email protected]> > rauschma.de > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss
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