LGTM2
/Daniel
On 2026-08-05 08:52, TAMURA, Kent wrote:
LGTM1. Interoperability/compatibility risk is very low.
On Wed, Aug 5, 2026 at 6:24 AM Javier Fernandez
<[email protected]> wrote:
*Contact emails*
[email protected]
*Specification*
https://www.w3.org/TR/css-typed-om-1/#stylevalue-subclasses
*Summary*
The CSS Typed OM spec exposes the CSSStyleValue hierarchy to
worker global scopes ([Exposed=(Window, Worker, PaintWorklet,
LayoutWorklet)]), but Blink only exposed CSSStyleValue,
CSSKeywordValue, CSSNumericValue, CSSUnitValue and
CSSUnparsedValue to Window and the worklets. As a result these
constructors were undefined in Workers, unlike in Firefox and Safari.
*Blink component*
Blink>CSS
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ECSS%22>
*Web Feature ID*
css-typed-om <https://webstatus.dev/features/css-typed-om>
*Motivation*
Aligns Chrome with the spec's [Exposed] set and removes a
cross‑thread inconsistency (these constructors are currently
undefined in workers); enables off‑main‑thread CSS value manipulation
*Initial public proposal*
/No information provided/
*TAG review*
/No information provided/
*TAG review status*
Not applicable
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
This feature is already shipped by Firefox and Safari and it's
purely additive worker‑scope exposure; zero change to existing
Window behavior; matches the spec. Only theoretical risk: content
that feature‑detects these globals inside a worker
/Gecko/: Shipped/Shipping
/WebKit/: Shipped/Shipping
/Web developers/: No signals
/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 special tooling; interfaces work in the worker DevTools console
like any other worker‑exposed API
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?*
Yes
*Is this feature fully tested byweb-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
css/css-typed-om/stylevalue-subclasses/*.any.js
(global=window,worker): cssKeywordValue, cssKeywordValue-value,
cssUnparsedValue-empty, numeric-objects/cssUnitValue-to; and
(full‑scope) the converted create-a-type, cssMathInvert-type,
cssMathNegate-type, add-two-types,
cssnumericvalue-multiply-two-types, arithmetic, to .any.js. (The
CSSMath* ones require the full‑scope
exposure.)https://wpt.fyi/results/css/css-typed-om/stylevalue-subclasses?label=experimental&label=master&aligned
<https://wpt.fyi/results/css/css-typed-om/stylevalue-subclasses?label=experimental&label=master&aligned>
*Flag name on about://flags*
/No information provided/
*Finch feature name*
/No information provided/
*Non-finch justification*
This is just a minor CSS change to allow some CSS javascript
bindings to be run in Worker context, but that were already
exposed to the Web via Window context.
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/534781956
*Estimated milestones*
Shipping on desktop 153
Shipping on Android 153
Shipping on WebView 153
*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).
https://github.com/w3c/csswg-drafts/issues/14229
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5114591051907072?gate=6116938171416576
This intent message was generated byChrome Platform Status
<https://chromestatus.com/>.
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TAMURA Kent
Software Engineer, Google
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