[web-animations-2] Should Triggers have any effect on non time-driven animations?

[ydaniv]

Currently AnimationTriggers' effect on time-driven animations is well defined:

An animation trigger is used to control the playback of its associated animation for time-driven animations.

Should there also be an effect of Triggers on non time-driven animations, e.g. scroll-driven animations?

Option 1

No effect, they are simply ignored.

Option 2

They behave exactly the same.
If we create an Animation() in WAAPI it doesn't apply any effect until .play() is invoked. The same is true for scroll-driven animations.
Using a Trigger practically replaces the need to call .play(), so we could just define that to have the same effect.
Now we need to define how each type interacts with these animations:

• once: the animation becomes active once trigger's active interval is entered.
• repeat: the animation switches between active/inactive on trigger's active interval entry and exit.
• alternate: the animation switches direction on trigger's active interval entry and exit.
• state: the animation's play-state is toggled on trigger's active interval entry and exit.

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Since I'm not seeing any reason to prevent it, I'm leaning towards option 2.

Proposal: amend the spec to say AnimationTriggers' effect is apply to all animations time-based and non time-based alike.