fix: reading an unset style property returns "" per CSSOM, not undefined#328
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magicismight wants to merge 1 commit into
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fix: reading an unset style property returns "" per CSSOM, not undefined#328magicismight wants to merge 1 commit into
magicismight wants to merge 1 commit into
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Reading a property that is not set — via `el.style.someProp` or
`el.style.getPropertyValue("some-prop")` — returned undefined, but CSSOM
defines both as the empty string (the property getter is routed through the
same handler as getPropertyValue). Callers that assume the spec, e.g.
`el.style.color.replaceAll(...)`, crash on the undefined. Normalize an absent
property to "" in the style getter.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
Reading a style property that isn't set returns
undefined, but per CSSOM both the camel-cased property getter andgetPropertyValue()must return the empty string for an unset property.Because the property getter is routed through the same handler as
getPropertyValue, both are affected. Code that assumes the spec — e.g.el.style.color.replaceAll(...)or any string method — throwsCannot read properties of undefinedon an element that simply hasn't set that property. This bites libraries that parse arbitrary HTML and read inline styles (ProseMirror's DOMParser, etc.).Fix
Normalize an absent property to
""in the style getter (esm/interface/css-style-declaration.js), which also coversgetPropertyValue. Setting/removing/serialization are untouched; a set property still returns its value, andcssTextis unchanged.CJS is regenerated via
npm run cjs. A test is added intest/interface/css-style-declaration.js; the full suite (node test/index.js) passes.Not a duplicate
Distinct from the open CSS issues:
<style>sheets (element.sheet), not the inlineelement.styledeclaration.el.style.property = ''ande.style.setProperty('property', '')should delete the property #327 concerns setting an empty string (delete semantics), not reading an unset property.