Re: [csswg-drafts] Interaction with Safari's back/forward previews (#8333)

For any other outsiders reading about this: The current state-of-the-art proposal for dealing with default UA back/forward transitions in Safari and Android seems to be at [default-ua-transitions.md](https://github.com/WICG/view-transitions/blob/main/default-ua-transitions.md). This was last updated in 2023.

I also have a couple of questions:

In https://github.com/whatwg/html/issues/8782#issuecomment-1591586904, @khushalsagar explains:

> That's why we need a 2 part API for this problem:
> 
> 1. An API which lets the author specify whether they prefer to override a navigation transition.
> 2. An API which informs the author of the UA's decision.
> 
> This API [i.e., adding `hasUAVisualTransition` to `PopStateEvent` and `NavigateEvent`] is doing 2. We'd like to not block this on 1 since its easier to do first and makes sense as a standalone API. UAs already make the decision for whether to choose UA or author transition which this API communicates to the author.

As far as I can tell, whatwg/html#8782 only addresses informing the author of the UA’s decision on whether it will use the author’s visual transition in *same-document* transitions.

But it does *not* seem to address informing the author of the UA’s decision in *cross-document* transitions, since `hasUAVisualTransition` requires JavaScript.

1. Is the expectation that a UA will simply not animate an author-provided cross-document transition whenever the UA prefers to do its own default transition (like when swiping back/forward in history)?
2. I don’t see any active issues in this repository devoted to [default-ua-transitions.md](https://github.com/WICG/view-transitions/blob/main/default-ua-transitions.md).
   - Has there been recent work on the “API which lets the author specify whether they prefer to override a navigation transition”?
   - Should a new issue devoted to that API be opened here?

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Received on Thursday, 8 May 2025 21:18:44 UTC