fix(attributes): use CSS whitespace for token matching by xiehuanyi · Pull Request #1911 · fb55/css-select

xiehuanyi · 2026-10-12T18:42:46Z

[class~=foo] currently matches class="foo\u00a0bar", while [class~="foo\u00a0bar"] cannot match the complete token. JavaScript \s includes NBSP, EM SPACE and vertical tab; CSS uses only TAB, LF, FF, CR and SPACE as whitespace (Selectors §3.7, attribute selectors).

Use those five characters for both the ~= selector-value check and attribute token boundaries. The tests cover non-CSS whitespace as token content, case-insensitive matching, and all five CSS separators.

Validation: the new suite fails in three cases before the change; npm test passes with 225 tests and one existing skipped test, including ESLint, TypeScript and Biome checks. npm run build and git diff --check pass.

Prepared and tested with OpenAI Codex assistance. This covers token whitespace; the separate empty-value issue already has PR #1810.

Summary by CodeRabbit

Bug Fixes
- Attribute selectors now split tokens only on CSS whitespace characters: tabs, line feeds, form feeds, carriage returns, and spaces. Other whitespace-like characters, including non-breaking spaces, remain part of the token rather than creating a boundary. Selectors match the complete token as expected, including when case-insensitive matching is used; the text on either side of a non-breaking space does not match as separate tokens.

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chatgpt-codex-connector · 2026-10-12T18:42:57Z

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-06T17:17:46.684856Z	`4f04e83`	New commits

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coderabbitai · 2026-10-12T18:43:07Z

No actionable comments were generated in the recent review.

Walkthrough

Attribute selector tokenization now treats only tab, line feed, form feed, carriage return, and space as separators. A test checks that NBSP remains within one token.

Changes: Attribute Tokenization

Layer / File(s)	Summary
Whitespace matching and token boundaries `src/attributes.ts`, `test/attributes.ts`	The whitespace and token-boundary regexes now recognize five CSS whitespace characters. The test verifies that NBSP does not split a `~=` attribute value, with and without the `i` flag.

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

Change: Bug fix

Possibly related PRs

fb55/css-select#1916: Also changes [attr~=value] matching, by rejecting empty values before boundary matching.

Suggested reviewers: fb55

Merge Risk: Minimal · up to 4f04e

The change preserves NBSP within attribute tokens. No merge-blocking risk was established.

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 change to use CSS whitespace for attribute token matching.
Docstring Coverage		Docstring coverage is inconclusive: files from earlier reviews still need to be rechecked within the check's analysis limits. Not blocking.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks the tokens tight
Five spaces mark the boundary right
NBSP stays with its token mate
Case-insensitive matches wait
The tests confirm the parsing state}

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Commits

Reviewing files that changed from the base of the PR and between `66e3e2f` and `4f04e83`.

Files selected for processing: 1

`test/attributes.ts`

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cubic-dev-ai

No issues found across 2 files

_{View guided diff | Re-trigger cubic}

greptile-apps · 2026-10-12T18:45:13Z

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge.

Summary

Changes ~= matching to use CSS whitespace instead of JavaScript whitespace.

Attribute token selectors split values only at CSS whitespace.

_{Reviews (2) · Last reviewed commit: "test(attributes): test one non-CSS white..." · Reviewed by Greptile}

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

All five cases pass on master, where `\s` already splits on them. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

NBSP, EM SPACE and VT all reach the same character class, so one case covers the path. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cubic-dev-ai

1 issue found across 1 file (changes from recent commits).

Prompt for AI agents (unresolved issues)


Check if these issues are valid — if so, understand the root cause of each and fix them. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="test/attributes.ts">

<violation number="1" location="test/attributes.ts:14">
P2: This test now exercises only NBSP, so a regression that treats TAB, LF, FF, CR, or SPACE as token content would pass the suite. Retain a parameterized assertion for all five CSS separators.</violation>
</file>

_{Reply with feedback, questions, or to request a fix.

View guided diff | Re-trigger cubic}

cubic-dev-ai · 2026-11-06T17:18:07Z

+        it("should keep non-CSS whitespace inside a token", () => {
+            const token = "foo\u{A0}bar";
+            const document = parseDocument(`<i class="${token}"></i>`);
+            expect(CSSselect.selectAll("[class~=foo]", document)).toHaveLength(
+                0,
+            );
+            expect(CSSselect.selectAll("[class~=bar]", document)).toHaveLength(
+                0,
+            );
+            expect(
+                CSSselect.selectAll(`[class~="${token}"]`, document),
+            ).toStrictEqual(document.children);
+            expect(
+                CSSselect.selectAll(
+                    `[class~="${token.toUpperCase()}" i]`,
+                    document,
+                ),
+            ).toStrictEqual(document.children);
+        });


P2: This test now exercises only NBSP, so a regression that treats TAB, LF, FF, CR, or SPACE as token content would pass the suite. Retain a parameterized assertion for all five CSS separators.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At test/attributes.ts, line 14: <comment>This test now exercises only NBSP, so a regression that treats TAB, LF, FF, CR, or SPACE as token content would pass the suite. Retain a parameterized assertion for all five CSS separators.</comment> <file context> @@ -11,46 +11,25 @@ const domChilds = dom.children as Element[]; - ).toBe(boolbase.falseFunc); - }, - ); + it("should keep non-CSS whitespace inside a token", () => { + const token = "foo\u{A0}bar"; + const document = parseDocument(``); </file context>

Suggested change

it("should keep non-CSS whitespace inside a token", () => {

const token = "foo\u{A0}bar";

const document = parseDocument(``);

expect(CSSselect.selectAll("[class~=foo]", document)).toHaveLength(

0,

);

expect(CSSselect.selectAll("[class~=bar]", document)).toHaveLength(

0,

);

expect(

CSSselect.selectAll(`[class~="${token}"]`, document),

).toStrictEqual(document.children);

expect(

CSSselect.selectAll(

`[class~="${token.toUpperCase()}" i]`,

document,

),

).toStrictEqual(document.children);

});

it("should keep non-CSS whitespace inside a token", () => {

const token = "foo\u{A0}bar";

const document = parseDocument(``);

expect(CSSselect.selectAll("[class~=foo]", document)).toHaveLength(

0,

);

expect(CSSselect.selectAll("[class~=bar]", document)).toHaveLength(

0,

);

expect(

CSSselect.selectAll(`[class~="${token}"]`, document),

).toStrictEqual(document.children);

expect(

CSSselect.selectAll(

`[class~="${token.toUpperCase()}" i]`,

document,

),

).toStrictEqual(document.children);

});

it.each(["\t", "\n", "\f", "\r", " "])(

"should split tokens on CSS whitespace %j",

(space) => {

const document = parseDocument(

``,

);

expect(

CSSselect.selectAll("[class~=foo]", document),

).toStrictEqual(document.children);

expect(

CSSselect.selectAll("[class~=bar]", document),

).toStrictEqual(document.children);

expect(

CSSselect._compileUnsafe(`[class~="foo${space}bar"]`),

).toBe(boolbase.falseFunc);

},

);

Intentional: the five-separator rows all pass on master (\s already splits on them), so they don't test this change; splitting on spaces stays covered by the existing ~= tests ([data-foo~=IT i], the nwmatcher [class~=…] cases). The remaining NBSP row is the one that fails without the fix.

🤖 Generated with Claude Code, using Opus 5.5.

fix(attributes): use CSS whitespace for token matching

66e3e2f

Copilot AI balanced review requested due to automatic review settings October 12, 2026 18:42

Copilot AI reviewed Oct 12, 2026

cubic-dev-ai Bot reviewed Oct 12, 2026

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coderabbitai Bot approved these changes Oct 12, 2026

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fb55 and others added 3 commits November 5, 2026 15:42

Merge branch 'master' into fix/ascii-attribute-token-whitespace

8dc3ae4

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test(attributes): drop the CSS whitespace split test

cc39cd6

All five cases pass on master, where `\s` already splits on them. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test(attributes): test one non-CSS whitespace character

4f04e83

NBSP, EM SPACE and VT all reach the same character class, so one case covers the path. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cubic-dev-ai Bot reviewed Nov 6, 2026

View reviewed changes

coderabbitai Bot approved these changes Nov 6, 2026

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fb55 merged commit 3a34d99 into fb55:master Nov 6, 2026
12 checks passed

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fix(attributes): use CSS whitespace for token matching - #1911

fix(attributes): use CSS whitespace for token matching#1911
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xiehuanyi:fix/ascii-attribute-token-whitespace

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