1362272 - Implement notifying of rejected promises (PromiseRejectionEvent)

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement, P2)

Description

[Ben Tian (inactive)]

This bug is to
1) implement notifying of rejected promises per HTML spec [1] and fire PromiseRejectionEvent [2], and
2) enable PromiseRejectionEvent interface implemented in bug 1338059.

Note bug 1338059 implements PromiseRejectionEvent interface but disables it until we actually fire the events.


[1] Section 8.1.3.12 Unhandled promise rejections 
https://html.spec.whatwg.org/multipage/webappapis.html#unhandled-promise-rejections
[2] https://html.spec.whatwg.org/multipage/webappapis.html#promiserejectionevent

Comment 1

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Ben, are you planning to continue working on this?

Comment 2

[Ben Tian (inactive)]

Sure. Take this bug.

Comment 3

[Eric Shepherd [:sheppy]]

Added DDN keyword for tracking for doc purposes. Also added "PromiseRejectionEvent" to the summary to help make this bug easier to find using a quick search.

Comment 4

[:Harald Kirschner :digitarald]

ni? :overholt to prioritize this given the new information we have on usage.

Comment 5

[Andrew Overholt [:overholt]]

On our list :)

Comment 6

[Sam Sneddon [:gsnedders]]

Note that this could cause bogus successes in tests, given testharness.js (by default) is meant to fail if there's unhandled rejections.

Comment 7

[Cheng-You Bai [:cybai] UTC+9]

unhandledrejection lands in Servo at https://github.com/servo/servo/pull/20755

Comment 8

[Edgar Chen [:edgar]]

Attachment: Bug 1362272 - Part 1: Add onrejectionhandled and onunhandledrejection EventHandler;

Comment 9

[Edgar Chen [:edgar]]

Attachment: Bug 1362272 - Part 2: Implement notifying of rejected promises;

Comment 10

[Edgar Chen [:edgar]]

Attachment: Bug 1362272 - Part 3: Enable on nightly and update tests;

Comment 11

[Edgar Chen [:edgar]]

https://treeherder.mozilla.org/#/jobs?repo=try&tier=1&exclusion_profile=false&revision=89715089bb4c5dbcb594ca13a29e5072b1c9aea4&group_state=expanded

Comment 12

[Edgar Chen [:edgar]]

(In reply to Edgar Chen [:edgar] from comment #10)

Created attachment 9040755 [details]
Bug 1362272 - Part 3: Enable on nightly and update tests;

I am going to do this in a separated bug.

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9ccbfb3293c
Part 1: Add onrejectionhandled and onunhandledrejection EventHandler; r=smaug
https://hg.mozilla.org/integration/autoland/rev/d7eaeddfd71d
Part 2: Implement notifying of rejected promises; r=smaug

Comment 14

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/a9ccbfb3293c
https://hg.mozilla.org/mozilla-central/rev/d7eaeddfd71d

Comment 15

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/16869 for changes under testing/web-platform/tests

Comment 16

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged

Comment 17

[Eric Shepherd [:sheppy]]

This was already mostly documented, but I've polished things up and done the rest of the remaining bits:

• Cleaned up and improved PromiseRejectionEvent
• JavaScript Guide section Promise rejection events already exists
• All other related content reviewed and looks good.
• Added to Firefox 69 for developers
• Submitted BCD PR 44386 with changes needed there

Comment 18

[Kai [:schweinepriester]]

:sheppy and others, are you sure Firefox 68 is or will be correct and not 69?

Via https://github.com/Fyrd/caniuse/pull/4972 and https://tests.caniuse.com/?feat=unhandledrejection leading to the comparison: https://i.imgur.com/2Iphqre.png

Comment 19

[Hsin-Yi Tsai (she/her) [:hsinyi]]

(In reply to kai.hollberg from comment #18)

:sheppy and others, are you sure Firefox 68 is or will be correct and not 69?

Via https://github.com/Fyrd/caniuse/pull/4972 and https://tests.caniuse.com/?feat=unhandledrejection leading to the comparison: https://i.imgur.com/2Iphqre.png

The implementation landed in 68 in this bug. We enabled it from 69 in bug 1525554 instead.

Comment 20

[David Spector]

This bug is Resolved, yet I have encountered a failure of Firefox to send both the rejectionhandled and onunhandledrejection events, in accordance with its own documentation (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises, https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent). When I omit a "catch()" for a Promise that Rejects, the Web Console reports that an unhandled exception occurred. There seems to be no way to report this programming error to the user, since try/catch fails, probably due to Promise having its own try/catch. I am using the latest public Firefox, 68.0.2. (This problem is not urgent for me, I just don't think it is right that the documentation and functionality are not kept in sync with each other.)

Comment 21

[David Spector]

Perhaps the Mozilla documentation (site:developer.mozilla.org/en-US/docs) is not included in github? It should be, so it can be synchronized with function and bug releases.

Comment 24

[David Spector]

If there is no current reason to keep this feature as enabled only in about:config, my vote would be to complete and release these window event notifications for real so they will alert developers to missing catch() functions or missing try/catch in their Promise or Await chains.

Comment 25

[Edgar Chen [:edgar]]

(In reply to David Spector from comment #24)

If there is no current reason to keep this feature as enabled only in about:config, my vote would be to complete and release these window event notifications for real so they will alert developers to missing catch() functions or missing try/catch in their Promise or Await chains.

Hi David, this feature is enabled by default in bug 1525554, it should be available after 69 release. Thanks.