980902 - Warn about use of sync XHR during unload and pagehide events

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

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

Currently we warn about use of sync XHR when we're outside unload event listeners.
Now that we have sendBeacon, there should be no reason to use sync XHR on the main thread.

Comment 1

[(no longer active)]

Except that it's not enabled by default yet, right? :-)

Comment 2

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

Ah. Well, let's fix this once it is enabled.

Comment 3

[Masatoshi Kimura [:emk]]

Bug 990220 enabled sendBeacon by default? What's left?
Sync XHR on unload is actually going to bite us (see bug 1109793 for example).

Comment 4

[Thomas Wisniewski [:twisniewski]]

Attachment: Bug 980902 - log a warning recommending the use of sendBeacon during unload instead of synchronous XMLHttpRequest; r?ehsan

log a warning recommending the use of sendBeacon during unload instead of synchronous XMLHttpRequest

Comment 5

[Thomas Wisniewski [:twisniewski]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=8ea4b9673f418b7c7814affb52d6093f78d3a1d5

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7dc8eb2bb2ec
log a warning recommending the use of sendBeacon during unload instead of synchronous XMLHttpRequest; r=Ehsan

Comment 7

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/7dc8eb2bb2ec

Comment 8

[Kohei Yoshino [:kohei]]

Posted site compatibility note: https://www.fxsitecompat.com/en-CA/docs/2019/use-of-sync-xhr-during-unload-pagehide-events-is-now-deprecated/

Comment 9

[Eric Shepherd [:sheppy]]

Added some more text to the article "Synchronous and asynchronous requests", part of the XHR documentation.