I've quite frequently required an `each` that returns the array, since I do sequential transformations that involve forEach, map, filter, sort etc.
I would not overload `each` with any early termination, I would probably have an `Array.prototype.takeWhile` method for that (which returns a new array taking elements while the return value of the predicate is truthy). On Tue, 25 Jul 2017 at 04:09 Tab Atkins Jr. <[email protected]> wrote: > On Mon, Jul 24, 2017 at 3:31 PM, T.J. Crowder > <[email protected]> wrote: > > On Mon, Jul 24, 2017 at 9:58 PM, Tab Atkins Jr. <[email protected]> > > wrote: > >> In general, functions returning undefined are *often* safe to switch > >> to returning a more useful value > > > > I think we'd struggle to prove it could be done safely. For instance, > we'd > > have to differentiate between all the places that did something like > this: > > > > ```js > > someDataPromise().then(data => data.forEach(entry => > console.log(entry))); > > ``` > > > > ...that *do* and *do not* rely on the fact that promise resolves with > > `undefined`. (The above does not.) > > > > Hopefully, ones that do are few and far between. But webscale is massive, > > "few and far between" can be an unacceptably high number. > > > > If there were an appetite for `Array.prototype.each`, I'd like to address > > not just the return value but other issues with > `Array.prototype.forEach` as > > well (like step value, per-iteration updates of the index, stopping early > > [using `some` or `every` is sometimes perfect, other times semantically > > misleading]). I have some thoughts on doing that while retaining runtime > > efficiency for the common case and code simplicity. But I doubt the > appetite > > is there. > > Yeah, thus the "often". ^_^ It's been done a few times in DOM land > iirc. Relying on a promise to resolve to undefined is probably quite > rare; it would mean that you're explicitly testing for undefined on > the far end. Much more likely, in situations like that, is just > ignoring the resolution value, in which case switching it to an Array > is fine. > > ~TJ >
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