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Spec the forEach() operator #105

Merged
merged 3 commits into from
Feb 7, 2024
Merged

Spec the forEach() operator #105

merged 3 commits into from
Feb 7, 2024

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domfarolino
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@domfarolino domfarolino commented Jan 30, 2024

Prototype Chromium implementation (with WPTs): https://chromium-review.googlesource.com/c/chromium/src/+/5249869.


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@domfarolino domfarolino marked this pull request as ready for review January 30, 2024 21:59
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Feel free to take a look @keithamus, if you're interested. But no pressure.

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This one LGTM 👍

@@ -743,7 +743,76 @@ For now, see [https://github.com/wicg/observable#operators](https://github.com/w
<div algorithm>
The <dfn for=Observable method><code>forEach(|callback|, |options|)</code></dfn> method steps are:

1. <span class=XXX>TODO: Spec this and use |callback| and |options|.</span>
1. Let |p| [=a new promise=].
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This seems generally useful but I'm curious if there was any discussion weighing up why this should return a promise, vs undefined per Array#forEach, or if this should perhaps be renamed to differentiate itself from any symmetry of the array equivalent?

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@domfarolino domfarolino Jan 30, 2024

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I think the analogy is that this kind of since array iteration is synchronous and returns undefined when done, therefore Observable "iteration" (i.e., forEach()) would return a Promise<undefined>, since that will tell you when Observable "iteration" is is done (since it is asynchronous). That kind of timing information could be useful.

There is some discussion about this on #69, but basically I'm not sure there is much utility in any operator returning undefined ever, vs Promise<undefined> which carries strictly more information. But I'd be open to re-consideration if you want to strike up more conversation or file another issue.

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I don't want to rock the boat on what is likely well-thought out and a culmination of very long discussions, but having said that, part of me wonders if this is a little awkward and maybe it's just... not worth implementing forEach at all? I wonder how much value it adds. Presumably given how much of this is modeled on existing user-land libraries we can find some kind of usage figures to guide us on which API should be prioritized? Is forEach high in that list?

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I'm sure you have an answer for the above so I filed #106 to hopefully document that!

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As an individual operator, yeah I think forEach() is useful. If we don't provide it, people will basically just try and use map() in a non-idiomatic way to do the same thing, like this example which I think is an accurate portrayal of what would come, absent this operator: whatwg/dom#544 (comment).

Secondary to the utility, it provides parity with the Iterator helpers proposal which I think kinda backs up the utility argument, and makes things a bit more symmetrical.

This operator is kinda somewhat similar to https://rxjs.dev/api/operators/tap which is a really popular operator, although admittedly it is different in that it doesn't return an Observable. But you brought this point up in 2019 anyways, which seems reasonable.

In short, I think the operator is useful, however I'm open to discussing what it should return. The existing momentum points to Promise<undefined> but if we want to have further discussion I'm fine with that too.

chromium-wpt-export-bot pushed a commit to web-platform-tests/wpt that referenced this pull request Jan 30, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
chromium-wpt-export-bot pushed a commit to web-platform-tests/wpt that referenced this pull request Feb 6, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
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The Chromium implementation for this has landed with tests, so I'll merge this.

@domfarolino domfarolino merged commit 35b0376 into master Feb 7, 2024
2 checks passed
@domfarolino domfarolino deleted the forEach-operator branch February 7, 2024 14:52
github-actions bot added a commit that referenced this pull request Feb 7, 2024
SHA: 35b0376
Reason: push, by domfarolino

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
chromium-wpt-export-bot pushed a commit to web-platform-tests/wpt that referenced this pull request Feb 7, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}
aarongable pushed a commit to chromium/chromium that referenced this pull request Feb 7, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}
chromium-wpt-export-bot pushed a commit to web-platform-tests/wpt that referenced this pull request Feb 7, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}
moz-v2v-gh pushed a commit to mozilla/gecko-dev that referenced this pull request Feb 13, 2024
…e operator, a=testonly

Automatic update from web-platform-tests
DOM: Implement the `forEach()` Observable operator

This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}

--

wpt-commits: 910e4c850e0e43a1832f943e2782ffa8f06b3eb9
wpt-pr: 44300
jamienicol pushed a commit to jamienicol/gecko that referenced this pull request Feb 15, 2024
…e operator, a=testonly

Automatic update from web-platform-tests
DOM: Implement the `forEach()` Observable operator

This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}

--

wpt-commits: 910e4c850e0e43a1832f943e2782ffa8f06b3eb9
wpt-pr: 44300
gecko-dev-updater pushed a commit to marco-c/gecko-dev-wordified that referenced this pull request Feb 16, 2024
…e operator, a=testonly

Automatic update from web-platform-tests
DOM: Implement the `forEach()` Observable operator

This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: benbenlesh.com

R=masonfchromium.org

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <masonfchromium.org>
Commit-Queue: Dominic Farolino <domchromium.org>
Cr-Commit-Position: refs/heads/main{#1257328}

--

wpt-commits: 910e4c850e0e43a1832f943e2782ffa8f06b3eb9
wpt-pr: 44300

UltraBlame original commit: b7468884afeb181ab7f2ec3224e73d56c0091360
mbrodesser-Igalia pushed a commit to mbrodesser-Igalia/wpt that referenced this pull request Feb 19, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}
gecko-dev-updater pushed a commit to marco-c/gecko-dev-comments-removed that referenced this pull request Feb 20, 2024
…e operator, a=testonly

Automatic update from web-platform-tests
DOM: Implement the `forEach()` Observable operator

This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: benbenlesh.com

R=masonfchromium.org

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <masonfchromium.org>
Commit-Queue: Dominic Farolino <domchromium.org>
Cr-Commit-Position: refs/heads/main{#1257328}

--

wpt-commits: 910e4c850e0e43a1832f943e2782ffa8f06b3eb9
wpt-pr: 44300

UltraBlame original commit: b7468884afeb181ab7f2ec3224e73d56c0091360
marcoscaceres pushed a commit to web-platform-tests/wpt that referenced this pull request Feb 23, 2024
This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-foreach.

See WICG/observable#105.

For WPTs:
Co-authored-by: [email protected]

[email protected]

Bug: 1485981
Change-Id: I61344bad7fa4bac65146e1305a376fc1f5e55dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5249869
Reviewed-by: Mason Freed <[email protected]>
Commit-Queue: Dominic Farolino <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1257328}
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