Add a resetLonghands field to CSS shorthand properties#1872
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Add a resetLonghands field to CSS shorthand properties#1872
resetLonghands field to CSS shorthand properties#1872Conversation
Via #1851. Some shorthand properties may also reset a number of properties that they don't set. These properties are known as "reset-only sub-properties": https://drafts.csswg.org/css-cascade-5/#reset-only-sub-property This update adds a `resetLonghands` field in CSS extracts to shorthands that have reset-only sub-properties, leveraging the list maintained by @cdoublev in: https://github.com/cdoublev/css/blob/master/lib/properties/shorthands.js Affected properties: - `animation` (and the legacy `-webkit-animation`) - `background` - `border` - `font` - `mask` (and the legacy `-webkit-mask`) The list needs to be maintained manually, I'm afraid. I don't see any good way to extract the list of reset-only sub-properties automatically for now.
dontcallmedom
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Mar 12, 2026
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LGTM, with a potential improvement (likely for a separate PR)
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| const resetLonghands = getResetLonghands(prop, allProperties, propertiesByName); | ||
| if (resetLonghands && resetLonghands.length > 0) { | ||
| const validResetLonghands = resetLonghands.filter(lh => allProperties.has(lh)); |
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this apply to the existing code, but shouldn't we fail or at least log an error of some sort if not all resetLonghands are valid?
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Yes, I aligned with the approach that exists for building the longhands field itself for consistency, but I agree that we should fail in both cases.
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Via #1851. Some shorthand properties may also reset a number of properties that they don't set. These properties are known as "reset-only sub-properties": https://drafts.csswg.org/css-cascade-5/#reset-only-sub-property
This update adds a
resetLonghandsfield in CSS extracts to shorthands that have reset-only sub-properties, leveraging the list maintained by @cdoublev in:https://github.com/cdoublev/css/blob/master/lib/properties/shorthands.js
Affected properties:
animation(and the legacy-webkit-animation)backgroundborderfontmask(and the legacy-webkit-mask)The list needs to be maintained manually, I'm afraid. I don't see any good way to extract the list of reset-only sub-properties automatically for now.
Note: I haven't listed
animation-compositionas a reset-only sub-property foranimationyet, pending clarity on its inclusion, see #1851 (comment). To be determined before this PR is merged!