feat: add no-unmatchable-selectors rule
#301
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nzakas
requested changes
Oct 21, 2025
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| ## Background | ||
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| An unmatchable selector is one that can never match any element in any document. These are effectively dead code and usually indicate mistakes. |
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Let's give a couple of examples here.
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| const a = Number(node.a); | ||
| const b = Number(node.b); |
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Can you add a comment here describing what's happening? Either node.a or node.b can be null, in which case Number() converts it into 0. I don't think it's obvious from the code that this is an intentional behavior and not an oversight.
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Prerequisites checklist
What is the purpose of this pull request?
This PR introduces a new rule
no-unmatchable-selectorsto catch CSS selectors that can never match any elements, helping developers identify dead code and potential mistakes in their stylesheets.What changes did you make? (Give an overview)
no-unmatchable-selectorsrule that detects and reports selectors with impossible:nth-*()pseudo-class formulasRelated Issues
#186
This initial implementation focuses on
:nth-*()pseudo-classes, but I plan to expand the rule in follow-up PRs to cover additional scenarios.Is there anything you'd like reviewers to focus on?