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[csswg-drafts] [web-animations-1] Should setting the startTime of a play-pending animation to `null` have side effects?

From: Brian Birtles via GitHub <sysbot+gh@w3.org>
Date: Tue, 22 May 2018 05:26:39 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-325145519-1526966798-sysbot+gh@w3.org>
birtles has just created a new issue for https://github.com/w3c/csswg-drafts:

== [web-animations-1] Should setting the startTime of a play-pending animation to `null` have side effects? ==
Typically setting the start time of an animation should cancel any pending tasks. This provides applications with a way to synchronously seek/sync animations. Furthermore, by setting the start time to `null` applications can perform a synchronous pause.

However, if an animation is play-pending its start time will already be unresolved (`null`).

If the animation is play-pending when script sets the start time to `null` what should happen?

a. The change is redundant and should be ignored. (Seems intuitive from a JS point of view, redundant changes have no side effects.), _or_
b. The pending play task is canceled. (Currently speced behavior. Allows applications to perform a synchronous pause even in the play-pending state.)


const anim = elem.animate(...);
// anim.pending === true
// anim.startTime === null
// anim.currentTime === 0

anim.startTime = null;
// Is the animation still play-pending here?

(Firefox actually does (a) as an optimization but the spec says we should do (b) and I'm wondering which to fix.)

/cc @stephenmcgruer @flackr @graouts @dadaa

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2691 using your GitHub account
Received on Tuesday, 22 May 2018 05:26:42 UTC

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