Re: [csswg-drafts] [css-animations-2] Move scroll and event animation triggers to independent namespace (#12336)

If we do decide to introduce `timeline-trigger` then I think it's important to specify the API surface, so I think it should as follows (~bikesheding aside):

### `event-trigger: <name> <type>`
- `event-trigger-name`: for declaring the ident
- `event-trigger-type`: for specifying the event type
- I think adding `-action` here is incorrect, since it ties this declaration specifically with animations, and this declaration should simply be used to declare a reusable event source.

### `timeline-trigger: <name> <auto | view() | scroll() | pointer() | <dashed-ident>> <range-enter>? [/ <range-exit> ]?`
- `timeline-trigger-name`: for declaring the ident
- `timeline-trigger-source`: for specifying the timeline's ident or anonymous
- `timeline-trigger-range`: for specifying `<enter> / <exit>` ranges. These should be specified on the trigger, and not on the animation level.

### `animation-trigger: <start> <once | reverse | reset | pause>? <exit>?`
- `animation-trigger-start`: for specifying the ident of the event to be used to play
- `animation-trigger-action`: for specifying the exit action, by default this is `once`
- `animation-trigger-exit`: for specifying the exit event. By default this mirrors same event for event-triggers, and is not needed for timeline-triggers since they already inherently declare it using ranges. With `once` this is ignored

The remaining problems I see here is that timeline-triggers already declare an enter/exit pair and we don't want to mix them with event-triggers, so:
  1. `animation-trigger-exit` should not allow timeline-triggers
  2. `animation-trigger-exit` should be ignored if `animation-trigger-start` is a timeline-trigger

Would that be possible?

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Received on Wednesday, 20 August 2025 12:08:08 UTC