This is a side-issue to #9901 where this demo was mentioned.

To make this work, I basically need to hijack all animations and either pause them (when manually updating their currentTime) or give them non-DocumentTimelines (when attaching them to a ScrollTimeline).

The code to get all these animations is this:

const transition = document.startViewTransition(…);
await transition.ready;

const animations =
  document
    .getAnimations()
    .filter((anim) => {
      return anim.effect.target === document.documentElement && anim.effect.pseudoElement?.startsWith("::view-transition")
    });

While this works, it’s not very ergonomic. Therefore I’m suggesting something like ViewTransition.getAnimations() to easily get them:

const transition = document.startViewTransition(…);
await transition.ready;
const animations = transition.getAnimations();

This would also benefit Scoped Transitions, where you can have multiple View Transitions going on at once.