Chrome sets both KeyboardEvent.keyCode and KeyboardEvent.charCode of "keypress"
event to same value. On the other hand, our traditional behavior is, sets
one of them to 0.
Therefore, we need to set keyCode value to charCode value if the keypress
event is caused by a non-function key, i.e., it may be a printable key with
specific modifier state and/or different keyboard layout for compatibility
with Chrome. Similarly, we need to set charCode value to keyCode value if
the keypress event is caused by a function key which is not mapped to producing
a character.
Note that this hack is for compatibility with Chrome. So, for now, it's enough
to change the behavior only for "keypress" event handlers in web content. If
we completely change the behavior, we need to fix a lot of default handlers
and mochitests too. However, it's really difficult because default handlers
check whether keypress events are printable or not with following code:
> if (event.charCode &&
> !event.altKey && !event.ctrlKey && !event.metaKey) {
or
> if (!event.keyCode &&
> !event.altKey && !event.ctrlKey && !event.metaKey) {
So, until we stop dispatching "keypress" events for non-printable keys,
we need complicated check in each of them.
And also note that this patch changes the behavior of KeyboardEvent::KeyCode()
when spoofing is enabled and the instance is initialized by initKeyEvent() or
initKeyboardEvent(). That was changed by bug 1222285 unexpectedly and keeping
the behavior makes patched code really ugly. Therefore, this takes back the
old behavior even if spoofing is enabled.
Differential Revision: https://phabricator.services.mozilla.com/D7974
--HG--
extra : moz-landing-system : lando
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