- From: Jan Varga via GitHub <noreply@w3.org>
- Date: Thu, 30 Apr 2026 09:41:41 +0000
- To: public-css-archive@w3.org
janvarga has just created a new issue for https://github.com/w3c/csswg-drafts:
== [css-typed-om-1] Should scroll-position in will-change reify as CSSKeywordValue or be unsupported? ==
There appears to be an interop mismatch between engines when setting the `scroll-position` keyword for `will-change` and retrieving it through Typed OM.
Consider:
```js
document.body.style.willChange = "scroll-position";
console.log(document.body.attributeStyleMap.get("will-change"));
````
Current behavior differs across engines:
* **Chrome**
* `attributeStyleMap.get('will-change')` -> `CSSStyleValue {}` (unsupported)
* **Safari**
* `attributeStyleMap.get('will-change')` -> `CSSKeywordValue { value: "scroll-position" }`
* **Firefox** (in progress)
* `attributeStyleMap.get('will-change')` -> `CSSKeywordValue { value: "scroll-position" }`
Other keyword values for `will-change` appear to be handled consistently across engines.
It seems unclear whether `scroll-position` should be treated as a supported keyword and reified as `CSSKeywordValue`, or whether it should be treated as unsupported in Typed OM.
Links:
- https://wpt.fyi/results/css/css-typed-om/the-stylepropertymap/properties/will-change.html?label=experimental&label=master&aligned
- https://github.com/web-platform-tests/wpt/blob/master/css/css-typed-om/the-stylepropertymap/properties/will-change.html#L21
- https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/css/cssom/style_value_factory.cc;l=245
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13867 using your GitHub account
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Received on Thursday, 30 April 2026 09:41:42 UTC