On Mon, Jul 24, 2017 at 9:58 PM, Tab Atkins Jr. <jackalmage at gmail.com>
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.

-- T.J. (er, the other one) Crowder
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On Mon, Jul 24, 2017 at 9:58 PM, Tab Atkins Jr. <jackalmage at gmail.com>
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.

-- T.J. (er, the other one) Crowder