[NevanDeCoteau]

Fixes #1910

Per the CSS spec, [a~=""] matches nothing. css-select matched elements with an empty value and values with leading, trailing or doubled spaces, because an empty value produced a regex that matches the empty string.

This change makes the ~= rule return falseFunc for an empty value, the same way it already does for values containing whitespace.

Tests added to test/attributes.ts:

[foo~=''] compiles to falseFunc
[a~=""] matches none of the four elements from the issue
[a~="x"] still matches whole words

I confirmed the new tests fail without the fix. The full test suite and lint pass locally.

Summary by CodeRabbit

• Bug Fixes
  • Attribute selectors using ~= with an empty value now match no elements. Selectors using ~= with a non-empty value continue to match elements as expected, including cases where the value appears among an element’s whitespace-separated attribute values.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-06T01:56:01.803081Z	62353b7	New commits

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[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

The ~= attribute selector now returns a non-matching function when its value is empty or contains whitespace. Tests cover the compiled matcher and DOM selection for empty and non-empty values.

Changes: Empty ~= Matching

Layer / File(s)	Summary
Reject empty ~= values src/attributes.ts, test/attributes.ts	The selector rejects empty values as well as values containing whitespace. Tests verify that an empty value matches no elements and that x matches three elements.

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix · Severity of issue fixed: Low

Merge Risk: Minimal · up to 62353

Empty-value selectors should no longer match elements. No material merge risk was identified.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly describes the fix for empty ~= attribute values.
Linked Issues check		[#1910] src/attributes.ts returns falseFunc for an empty ~= value. test/attributes.ts checks that the selector compiles to falseFunc. This covers all four reported attribute values. The DOM …
Out of Scope Changes check		[#1910] The change summary identifies only the attribute rule and its tests. Both support the issue. The incremental diff was unavailable, but the whole-PR summary establishes the reported scope.
Docstring Coverage		Docstring coverage is inconclusive: files from earlier reviews still need to be rechecked within the check's analysis limits. Not blocking.

Full details: Linked Issues check

Explanation

[#1910] src/attributes.ts returns falseFunc for an empty ~= value. test/attributes.ts checks that the selector compiles to falseFunc. This covers all four reported attribute values. The DOM selection tests described in the summary are not present in the inspected head file.

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_{A rabbit checks the selector’s cue
Empty words now match nothing through
Whitespace still gets turned away
Three x results pass the test today
I hop through fields, then nibble hay}

Recent review info

Run configuration

• Source mode: Auto
• Repository: Unavailable
• Branch: Unavailable
• File: No configuration file from this repository applied
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• Layers: Organization UI
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: 778de318-bfb6-445c-a3e5-fa124f13568e

Commits

Reviewing files that changed from the base of the PR and between 582097c and 62353b7.

Files selected for processing: 1

• src/attributes.ts

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

[cubic-dev-ai]

No issues found across 2 files

_{View guided diff | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge.

Summary

Empty ~= attribute selectors now match nothing.

• Empty ~= selectors match no elements.

_{Reviews (2) · Last reviewed commit: "refactor(attributes): shorten the empty ..." · Reviewed by Greptile}