LGTM3 (I see security is approved now)
On 10/15/26 4:29 a.m., Philip Jägenstedt wrote:
Can you take care of the Security gate in chromestatus.com
<http://chromestatus.com> so that the last API owner approver does not
need to bypass that?
On Thu, Oct 15, 2026 at 10:28 AM Philip Jägenstedt
<[email protected]> wrote:
LGTM2
On Thu, Oct 15, 2026 at 10:02 AM Yoav Weiss (@Shopify)
<[email protected]> wrote:
On Wednesday, October 7, 2026 at 6:18:53 PM UTC+3 Rick Byers
wrote:
Looks good to me, but is there any reason this PR can't
land now?
It needed some more work. It has landed now.
On Wed, Sep 30, 2026 at 5:35 PM Alex Russell
<[email protected]> wrote:
LGTM1; this is an awesome addition. Thanks for making
it happen.
On TAG review, can you please send an FYI?
Best,
Alex
On Wednesday, September 30, 2026 at 2:47:22 PM UTC+1
Yoav Weiss wrote:
*Contact emails*
[email protected]
*Explainer*
https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369
<https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369>
*Specification*
https://github.com/w3c/long-animation-frames/pull/30
<https://github.com/w3c/long-animation-frames/pull/30>
*Summary*
Add `styleDuration` and `forcedStyleDuration`
information to the Long Animation Frame API,
enabling developers to distinguish style and
layout times.
*Blink component*
Blink>PerformanceAPIs
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%22>
*Web Feature ID*
Missing feature -
https://github.com/web-platform-dx/web-features/issues/4453
<https://github.com/web-platform-dx/web-features/issues/4453>
*Motivation*
Currently performance-conscious developers have no
way to distinguish their style time from their
layout time, making CSS performance issues less
actionable than they can be. This feature enables
developers to make that distinction.
*Initial public proposal*
https://github.com/w3c/long-animation-frames/pull/30
<https://github.com/w3c/long-animation-frames/pull/30>
*TAG review*
I didn't file for a TAG review as these are a few
new attributes that break up the timings provided
by an existing attribute, mimicking its existing
shape. I don't expect the TAG to have strong
opinions on the shape of the attributes.
*TAG review status*
Not applicable
*Origin Trial Name*
Long Animation Frames - separate style and layout
durations
*Goals for experimentation*
See that the new attributes provide useful data to
developers as they debug their CSS performance issues.
*Chromium Trial Name*
LongAnimationFrameStyleDuration
*Link to origin trial feedback summary*
https://groups.google.com/a/chromium.org/g/blink-dev/c/qvGqBcSOFTQ/m/rU6rqKuMCAAJ
<https://groups.google.com/a/chromium.org/g/blink-dev/c/qvGqBcSOFTQ/m/rU6rqKuMCAAJ>
*Origin Trial documentation link*
https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369
<https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369>
*WebFeature UseCounter name*
kLongAnimationFrameTimingStyleDuration
*Risks*
*Interoperability and Compatibility*
/As these are new attributes, I don't expect them
to have any compat impact. As far as interop goes,
I'd expect that when other engines adopt LoAF,
they'd also adopt these attributes./
/Gecko/: No signal
Positive on the broader LoAF:
https://github.com/mozilla/standards-positions/issues/929
<https://github.com/mozilla/standards-positions/issues/929>
I'm asking if I should file a more specific issue
for these extra attributes.
/WebKit/: No
signal
(https://github.com/WebKit/standards-positions/issues/283
<https://github.com/WebKit/standards-positions/issues/283>)
No signal for the broader LoAF feature. Unlikely
they'd have a strong position on these attributes.
/Web developers/:
Positive
(https://groups.google.com/a/chromium.org/g/blink-dev/c/qvGqBcSOFTQ/m/5DCTOu9KCgAJ
<https://groups.google.com/a/chromium.org/g/blink-dev/c/qvGqBcSOFTQ/m/5DCTOu9KCgAJ>)
/Other signals/:
*WebView application risks*
Does this intent deprecate or change behavior of
existing APIs, such that it has potentially high
risk for Android WebView-based applications?
/No information provided/
*Debuggability*
/No information provided/
*Will this feature be supported on all six Blink
platforms (Windows, Mac, Linux, ChromeOS, Android,
and Android WebView)?*
Yes
*Is this feature fully tested by
web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
-
https://wpt.fyi/results/long-animation-frame/loaf-style-duration.html
<https://wpt.fyi/results/long-animation-frame/loaf-style-duration.html>:
styleDuration (9 subtests)
-
https://wpt.fyi/results/long-animation-frame/loaf-layout-duration.html
<https://wpt.fyi/results/long-animation-frame/loaf-layout-duration.html>:
layoutDuration (7 subtests)
-
https://wpt.fyi/results/long-animation-frame/loaf-forced-style-duration.html
<https://wpt.fyi/results/long-animation-frame/loaf-forced-style-duration.html>:
forcedStyleDuration (4 subtests)
-
https://wpt.fyi/results/long-animation-frame/loaf-forced-layout-duration.html
<https://wpt.fyi/results/long-animation-frame/loaf-forced-layout-duration.html>:
forcedLayoutDuration, including checking that
forced style plus forced layout
adds up to forcedStyleAndLayoutDuration (5
subtests)
-
https://wpt.fyi/results/long-animation-frame/loaf-container-queries.html
<https://wpt.fyi/results/long-animation-frame/loaf-container-queries.html>:
all four attributes when container queries mix
style and layout work (6 subtests)
-
https://wpt.fyi/results/long-animation-frame/loaf-toJSON.html
<https://wpt.fyi/results/long-animation-frame/loaf-toJSON.html>:
now also checks styleDuration and layoutDuration
in toJSON()
*Flag name on about://flags*
/No information provided/
*Finch feature name*
LongAnimationFrameStyleDuration
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/476826067
<https://issues.chromium.org/issues/476826067>
*Estimated milestones*
Shipping on desktop157Origin trial desktop
first148Origin trial desktop last153Shipping on
Android157Shipping on WebView157
*Anticipated spec changes*
Open questions about a feature may be a source of
future web compat or interop issues. Please list
open issues (e.g. links to known github issues in
the project for the feature specification) whose
resolution may introduce web compat/interop risk
(e.g., changing to naming or structure of the API
in a non-backward-compatible way).
/
/
/
No changes expected./
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5171478175809536?gate=6516503656660992
<https://chromestatus.com/feature/5171478175809536?gate=6516503656660992>
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJxRuMp6Ha5RVCjzNfsG0Sj96Y%3Dgy9LnxtM%2Brq-S6DEew%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJxRuMp6Ha5RVCjzNfsG0Sj96Y%3Dgy9LnxtM%2Brq-S6DEew%40mail.gmail.com>
Intent to Experiment:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJ2PJ0dZxYH48PALOSUenSSV7VuZ9CzTHnGd8u_jTKkcg%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJ2PJ0dZxYH48PALOSUenSSV7VuZ9CzTHnGd8u_jTKkcg%40mail.gmail.com>
This intent message was generated by Chrome
Platform Status <https://chromestatus.com/>.
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