If you don't want the iterable features neither the own properties, what're the benefits over a object indexed by numbers `const o = Object.create(null); o[0] = 12; ...`? About the other function proprosal (`Function.create`) I don't see any benefits in day to day use having a function without prototype
If you are interested in a performatic barebones fixed-sized arrays (like your C example) you should read about ArrayBuffers and Typed Array views[1]. Actually it is the closest to your example as Javascript could potentially get. [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Typed_arrays Em qui, 10 de jan de 2019 às 07:35, Sultan <thysul...@gmail.com> escreveu: > > >Why would this be better than `const a = []; Object.setPrototypeOf(a, null)`? > > In that example "a" value would still have "own" properties like length. > > a = Array.create(null, 10) > > Wouldn't have any own or prototype properties by design; It is mean to be > "bare-bones" or as close to a C-like: > > a = malloc(sizeof(void*)*10) > > as JavaScript could potentially get. > > On Thu, Jan 10, 2019 at 11:54 AM Jordan Harband <ljh...@gmail.com> wrote: >> >> Why would this be better than `const a = []; Object.setPrototypeOf(a, null)`? >> >> On Thu, Jan 10, 2019 at 12:09 AM Sultan <thysul...@gmail.com> wrote: >>> >>> >An array with no prototype wouldn't have any of the iteration methods on >>> >it... >>> >>> Yes, that is what is intended with this, similar to an Object.create(null) >>> object with number-ed keys. >>> >>> Alternatively one could look at the objects created from this to be the >>> "bare-bones" structure around these data-structures. >>> >>> That is the in-existence of prototypes and own properties like "length" >>> makes it clear that these "flat" objects are intended as author managed >>> objects. >>> >>> There are is no visible default prototype or own properties because the >>> author will create, expose and managed these for the data-structure >>> explicitly if need be or more commonly choose to not expose the >>> data-structure at all and use these for low-level internal book keeping for >>> other abstractions. >>> >>> This would create a new ceiling(or ground-level) for how "low-level" one >>> could go with JavaScript if these where part for the language and as a >>> secondary consequence allow engines to make stronger assumptions with >>> regards to operations on these structs. >>> >>> On Thu, Jan 10, 2019 at 9:48 AM Jordan Harband <ljh...@gmail.com> wrote: >>>> >>>> An array with no prototype wouldn't have any of the iteration methods on >>>> it; a function with no prototype wouldn't have .call/.bind/.apply - length >>>> and name are own properties of functions, and length is an own property of >>>> an array, so you'd get those regardless. >>>> >>>> (`Array.from({ length: 1000 })` already creates an array of length 1000 >>>> without holes, fwiw) >>>> >>>> On Wed, Jan 9, 2019 at 10:43 PM Sultan <thysul...@gmail.com> wrote: >>>>> >>>>> Identical to Object.create but for Arrays and Functions. >>>>> >>>>> This method will allow you to create arrays with no prototype. >>>>> >>>>> This would allow authors the ability to use array objects as state >>>>> containers without the need to resort to index-based objects with >>>>> >>>>> Object.create(null, length) >>>>> >>>>> When you want to both use an array-like struct as both a property and >>>>> index-able map. >>>>> >>>>> A side-effect of this would afford engines a strong heuristic for >>>>> avoiding holey-array look-ups operations when there's no prototype to >>>>> walk. >>>>> >>>>> For example the following would create an array with a length of 1000 >>>>> without "holes". >>>>> >>>>> const arr = Array.create(null, 1000) >>>>> >>>>> In addition this could also apply to functions with >>>>> >>>>> Function.create(null, () => {}) >>>>> >>>>> When you want to use functions as state-containers but don't want any of >>>>> the implicit properties(length, name) etc. >>>>> _______________________________________________ >>>>> es-discuss mailing list >>>>> es-discuss@mozilla.org >>>>> https://mail.mozilla.org/listinfo/es-discuss > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss -- Atenciosamente, Augusto Borges de Moura _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
