1717760 - initKeyEvent on KeyboardEvent should return undefined

Status: RESOLVED FIXED

(Core :: DOM: Events, enhancement, P3)

Description

[Karl Dubost💡 :karlcow]

Test

var i = document.createEvent("KeyboardEvent");
typeof i.initKeyEvent;

On Firefox it returns function
On Blink and WebKit browsers, it returns undefined

This creates at least a webcompat issue on startrack.com.au

Given that it is not implemented in Safari, Chrome and Edge, I have the feeling we can safely unship it. We could try on Nightly, and discover if any sites break.

I see Masayuki mentioning initKeyEvent() in Bug 1479964 Comment #25

I wonder if it's the relevant code.
https://searchfox.org/mozilla-central/rev/f351e19360729b351bfc7c1386d6e4ca4ea676e2/dom/events/KeyboardEvent.cpp#313-328

It's also not specified in the DOM Specification.
https://dom.spec.whatwg.org/

And defined as non standard and deprecated on MDN
https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/initKeyEvent

Comment 1

[Anne (:annevk)]

Masayuki, do you want to take this? I would suggest we add a preference that's false-by-default and use that to hide the method in IDL. Then if we don't notice anything we can remove it entirely after a couple of releases. Let's also do an intent to unship just in case.

Comment 2

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Hmm, it's an old API, so, I bet that there are some web apps in the wild which use it for detecting Firefox...

Comment 3

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

122,392 code results

https://github.com/search?q=initKeyEvent&type=Code
sigh... perhaps, we should do it with an allowed list, isn't it?

Comment 4

[Anne (:annevk)]

I'm not sure what that means? A lot of the code there seems to make usage conditional though and uses initKeyboardEvent() if not available, which is something all browsers expose.

Comment 5

[Kagami Rosylight [:saschanaz] (they/them)]

Yeah, I do see some code that calls initKeyEvent without existence check but those are just a few, and others are mostly from happen.js and jquery.simulate.js that have workarounds.

Comment 6

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Okay, I'll post a patch which just disables it with a pref.

Comment 7

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Attachment: Bug 1717760 - Stop using `KeyEvent.initKeyEvent` in our tests r=smaug!

Comment 8

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Attachment: Bug 1717760 - Disable `KeyEvent.initKeyEvent` by default r=smaug!

Now, Gecko is the only browser to support undocumented KeyEvent.initKeyEvent.
We should drop it by default because typeof KeyboardEvent.initKeyEvent is
used at least in a major web-site and which causes not working the web-site.

Depends on D121028

Comment 9

[Karl Dubost💡 :karlcow]

The webcompat team will watch out if there is new breakage where initKeyEvent would be used to identify/target Firefox.

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2ee20e58b0f1
Stop using `KeyEvent.initKeyEvent` in our tests r=smaug
https://hg.mozilla.org/integration/autoland/rev/81a7baecf0cb
Disable `KeyEvent.initKeyEvent` by default r=smaug

Comment 11

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

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/29963 for changes under testing/web-platform/tests

Comment 12

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/2ee20e58b0f1
https://hg.mozilla.org/mozilla-central/rev/81a7baecf0cb

Comment 13

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

Upstream PR merged by moz-wptsync-bot

Comment 14

[BugBot [:suhaib / :marco/ :calixte]]

Since the status are different for nightly and release, what's the status for beta?
For more information, please visit auto_nag documentation.

Comment 15

[Caitlin Neiman [:caitmuenster]]

We just emailed affected developers to let them know .initKeyEvent is deprecated as of Firefox 93 and will be unshipped in Firefox 96.

Comment 16

[Hamish Willee]

FYI FF93 MDN docs for this can be tracked in https://github.com/mdn/content/issues/8623. This is just addition of release note, and making information about the deprecation and the preference more clear on the page.
When you actually remove it we'll need to do a little more work in cleanup.