On 4/17/26 21:38, Emilio Cobos Álvarez wrote:
On 4/17/26 15:43, Dave Townsend wrote:
On Fri, 17 Apr 2026 at 14:05, Emilio Cobos Álvarez <[email protected]
<mailto:[email protected]>> wrote:
I did think about doing something like that, but it's actually not so
trivial, because `ownerGlobal` is a property on `EventTarget`, even
though we're only changing the behavior of `Node` here.
Do non-node EventTargets already have the new behaviour? I can't think of other
EventTargets that can be adopted but I might be missing something.
I mean, that depends on what do you mean with "the new behavior". No other objects allow otherwise switching prototypes / globals. But yeah adoption
is a node-specific concept (or at least I can't come up with similar examples off the top of my head).
Also, there are some use cases for `ownerGlobal`, too, I believe. For
example, creating derived objects like events to dispatch generally
should use it:
node.dispatchEvent(new node.ownerGlobal.CustomEvent(...));
I don't fully understand why we would dispatch an event from a different global into the new document, but if that's the case can we add an assert
that checks this?
Usually it is totally fine to dispatch events from different global. (Some UIEvents may depend on PresContext. Hopefully we aren't creating too many
MouseEvents from JS. Hmm, perhaps we should tweak mPresContext setup in UIEvents to get mPresContext from mTarget)
I do understand that for the front-end, having a convenient way
of getting to the global that the node is in (ownerDocGlobal,
currently)
is super handy and what 95+% of the code would want, tho...
If the non-Node EventTarget.ownerGlobal usage for bindings is minimal,
wdyt about renaming it from the bindings to something different / more
obviously not-what-you-usually want (or removing it even, perhaps)?
If keeping the existing behaviour of `ownerGlobal` isn't an option then I think we should switch to better named alternatives, perhaps
`currentGlobal` and `eventGlobal`.
I couldn't guess what eventGlobal might mean.
I think currentGlobal is a bit unclear on what it is. And the HTML spec actually defines that term which would make it confusing for platform
engineers IMHO.
ownerDocGlobal is pretty clear if it wasn't for ownerGlobal existing.
WDYT of:
* For now, I land the tweaks in [1].
* I investigate removing ownerGlobal from JS. Basically, push to try with
.ownerGlobal crashing for stuff that isn't a node and audit the results.
* Based on that we can decide whether to remove stuff or rename the two
accessors.
I assume we do need to have ownerGlobal on EventTarget, possibly renamed to
relevantGlobal. But perhaps I'm wrong :)
I'd like Olli's input on the names, as ideally we make C++ match those names too. The HTML spec has "relevant global" for our current ownerGlobal[2].
For the ownerDocGlobal that'd be something like "node document's relevant global" or so.
Would something like relevantGlobal / documentGlobal work for you?
I do like relevantGlobal and documentGlobal.
Not sure they will help too much, since the setup just is confusing when there are multiple globals around. We can't do much about that, since that is
what the web relies on.
-Olli
Thanks,
-- Emilio
[1]: https://phabricator.services.mozilla.com/D294805
[2]: https://html.spec.whatwg.org/#relevant
Thanks,
--Emilio
On 4/17/26 2:09 PM, Dave Townsend wrote:
> Hi Emilio. I'm concerned that this change in behaviour will cause
subtle
> bugs in existing or future code we write. In my mind and I'm sure
in the
> minds of many developers, `ownerGlobal` means the window the
element is
> in and that will be a hard perception to shift. Because it will
now mean
> something different only in rare cases we are likely to use the
wrong
> thing without noticing. Additionally the naming of `ownerGlobal` and
> `ownerDocGlobal` makes it very unclear that they mean different
things.
>
> Since `ownerGlobal` is not part of the web spec can we keep the same
> behaviour for `ownerGlobal` and introduce a new property for the
node's
> original window?
>
> On Thu, 16 Apr 2026 at 23:22, 'Emilio Cobos Álvarez' via firefox-
> [email protected] <mailto:[email protected]> <mailto:firefox-
[email protected] <mailto:[email protected]>> <firefox-
> [email protected] <mailto:[email protected]> <mailto:firefox-
[email protected] <mailto:[email protected]>>> wrote:
>
> Hey,
>
> Once I get bug 1470017 <https://bugzil.la/1470017 <https://
bugzil.la/1470017>> to stick, the
> `EventTarget.ownerGlobal` property on nodes will change behavior
> slightly.
>
> This will allow fixing long-standing web components issues
> (prototypes getting lost on adopt) and some other subtler
webcompat
> issues, like bug 2022763 <https://bugzil.la/2022763 <https://
bugzil.la/2022763>>.
>
> In most cases it should be fine to keep using it in the
front-end,
> but there are two subtle behavior changes that might need
code to be
> adjusted:
>
> * If you're dealing with nodes that might have been adopted,
> `ownerGlobal` might point to the original window of the node,
> not the one that's currently in.
> * .ownerGlobal might also now return non-null a bit more often
> (after the docshell is gone).
>
> If you need the old behavior, you can use the new
> `Node.ownerDocGlobal` property. I don't expect much fallout,
and I
> want to proactively change some more code to use `ownerDocGlobal`
> (e.g. child actors almost always want to look at the window
the node
> is in), but I thought it might be worth a PSA, reach out if
you see
> issues that might be caused by it on the chrome.
>
> Let me know if there are any questions.
>
> Thanks,
> -- Emilio
>
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