1358893 - Stop using nsDocument::CreateEvent("beforeunloadevent") internally

Status: RESOLVED FIXED

(Core :: DOM: Events, enhancement)

Description

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

We're trying to see if 

Chrome says they see almost zero usage of document.createEvent("beforeunloadevent"), so they're willing to drop support:

https://github.com/whatwg/dom/issues/362#issuecomment-295723397

We can't assess our usage, because we use it internally from C++ code instead of directly constructing the event.  We should stop doing that so we can figure out if webpages are actually using this event.

Comment 1

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Attachment: Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

We want to see if we can drop support due to web pages not using it.
Edge and Safari already don't support it, and Chrome reports that usage
is low enough that they're willing to drop it.  But telemetry doesn't
tell us about web usage if we're triggering it via our own internal
code.

Review commit: https://reviewboard.mozilla.org/r/132676/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/132676/

Comment 2

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/132676/diff/1-2/

Comment 3

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

Requesting data review.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

https://reviewboard.mozilla.org/r/132676/#review135520

Comment 5

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/132676/diff/2-3/

Comment 6

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/132676/diff/3-4/

Comment 7

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

Apparently I didn't actually try to compile this locally.  This makes me sad.  Sorry for the spam, but MozReview doesn't carry forward feedback flags.

Comment 8

[Benjamin Smedberg]

Comment on attachment 8860749 [details]
Bug 1358893 - Stop using document.createEvent("beforeunloadevent") internally;

data-r=me

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/eb2b2dec98d1
Stop using document.createEvent("beforeunloadevent") internally; r=smaug

Comment 10

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/eb2b2dec98d1