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 > > *Specification* > 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 > > *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 > > *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 > > *Origin Trial documentation link* > 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 > 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) > 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 > ) > > *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: > styleDuration (9 subtests) > - 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: > forcedStyleDuration (4 subtests) > - > 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: > all four attributes when container queries mix style and layout work (6 > subtests) > - 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 > > *Estimated milestones* > Shipping on desktop 157 > Origin trial desktop first 148 > Origin trial desktop last 153 > Shipping on Android 157 > Shipping on WebView 157 > > *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 > > *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 > Intent to Experiment: > 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/>. > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/9403784c-3fb5-47a6-b288-d6c4c26945bdn%40chromium.org.
