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Allow :is() and :where() selectors #789

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a92102d
Allow :is() and :where() selectors in selector validation
KH-Coder865 Feb 6, 2026
7e3300c
Automatic application of license header
github-actions[bot] Feb 6, 2026
8336e48
Updating tsconfig.json to resolve build
KH-Coder865 Feb 6, 2026
83383f5
Updating tsconfig.json to resolve build
KH-Coder865 Feb 6, 2026
15263f7
Applied Suggestive Changes
KH-Coder865 Feb 7, 2026
18d052e
Moved updated functionality to domutils
KH-Coder865 Feb 8, 2026
05b9aa3
Update packages/domutils/src/selector.ts
KH-Coder865 Feb 14, 2026
23cdd58
Finalized small changes
KH-Coder865 Mar 28, 2026
74b8138
Try to fix test
krassowski Mar 28, 2026
1e38ea7
Remove second copy of selector test
krassowski Mar 28, 2026
effc878
Move the `Selector` tests under the `Selector` group
krassowski Mar 28, 2026
4bce81f
Fix nesting of test cases
krassowski Mar 28, 2026
c01cfe5
Clarify error messages regarding selector commas
krassowski Mar 28, 2026
40f1a68
Add test for commas inside nested :is() selector
krassowski Mar 28, 2026
c30db48
lint
krassowski Mar 28, 2026
8635c88
Add another test
krassowski Mar 28, 2026
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2 changes: 1 addition & 1 deletion packages/commands/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1687,7 +1687,7 @@ namespace Private {
function validateSelector(
options: CommandRegistry.IKeyBindingOptions
): string {
if (options.selector.indexOf(',') !== -1) {
if (Selector.hasTopLevelComma(options.selector)) {
throw new Error(`Selector cannot contain commas: ${options.selector}`);
}
if (!Selector.isValid(options.selector)) {
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19 changes: 19 additions & 0 deletions packages/domutils/src/selector.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,25 @@ export namespace Selector {
export function matches(element: Element, selector: string): boolean {
return Private.protoMatchFunc.call(element, selector);
}

/**
* Remove :is() and :where() functional pseudo-classes so that
* commas inside them do not count as top-level selector separators.
*/
function stripIsWhere(selector: string): string {
return selector.replace(
/:(is|where)\(([^()]|\([^()]*\))*\)/g,
''
);
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Copilot AI Mar 28, 2026

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stripIsWhere() uses a regex that only handles limited parenthesis nesting. Valid selectors can nest functional pseudos (e.g. :is(:not(:is(.b,.c)))), and in those cases the regex won’t strip the outer :is(...), causing commas inside nested selectors to be treated as “top-level” and rejected. Consider replacing the regex with a small scanner that tracks parentheses depth and whether the current depth is inside an :is( / :where( function.

Suggested change
return selector.replace(
/:(is|where)\(([^()]|\([^()]*\))*\)/g,
''
);
let result = '';
const len = selector.length;
let i = 0;
while (i < len) {
const ch = selector[i];
if (
ch === ':' &&
(selector.startsWith('is(', i + 1) ||
selector.startsWith('where(', i + 1))
) {
// Determine which function name we matched.
const isIs = selector.startsWith('is(', i + 1);
const nameLen = isIs ? 2 : 5; // 'is' or 'where'
const openParenIndex = i + 1 + nameLen;
// Sanity check: ensure there is an opening parenthesis.
if (openParenIndex >= len || selector[openParenIndex] !== '(') {
// Fallback: treat ':' as a normal character.
result += ch;
i++;
continue;
}
// Skip over the entire :is(...) or :where(...) construct,
// correctly handling nested parentheses.
let depth = 1;
let j = openParenIndex + 1;
while (j < len && depth > 0) {
const cj = selector[j];
if (cj === '(') {
depth++;
} else if (cj === ')') {
depth--;
}
j++;
}
// Set i to the position after the closing parenthesis (or end of string).
i = j;
continue;
}
// Normal character, keep it.
result += ch;
i++;
}
return result;

Copilot uses AI. Check for mistakes.
}

/**
* Returns true if the selector contains a top-level comma.
*/
export function hasTopLevelComma(selector: string): boolean {
return stripIsWhere(selector).indexOf(',') !== -1;
}
Comment on lines +97 to +102
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Copilot AI Mar 28, 2026

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hasTopLevelComma() now allows selectors like .a:is(.b,.c), but Selector.calculateSpecificity()/Private.calculateSingle() still split the selector at the first comma (selector.split(',', 1)[0]). That will cut commas inside :is()/:where() and produce incorrect specificity values, which affects ordering logic in context menus and keybinding resolution. Please update specificity parsing to ignore commas inside :is()/:where() (or implement their Selectors Level 4 specificity rules) so the new allowed selectors don’t break precedence decisions.

Copilot uses AI. Check for mistakes.

}

/**
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18 changes: 18 additions & 0 deletions packages/domutils/tests/src/selector.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -167,4 +167,22 @@ describe('@lumino/domutils', () => {
});
});
});

describe('hasTopLevelComma()', () => {
it('allows commas inside :is()', () => {
expect(Selector.hasTopLevelComma('.a:is(.b,.c)')).to.equal(false);
});

it('allows commas inside :where()', () => {
expect(Selector.hasTopLevelComma('.a:where(.b,.c)')).to.equal(false);
});

it('rejects top-level commas', () => {
expect(Selector.hasTopLevelComma('.a, .b')).to.equal(true);
});

it('rejects mixed selectors', () => {
expect(Selector.hasTopLevelComma('.a:is(.b,.c), .d')).to.equal(true);
});
});
});
2 changes: 1 addition & 1 deletion packages/widgets/src/contextmenu.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,7 @@ namespace Private {
* invalid or contains commas.
*/
function validateSelector(selector: string): string {
if (selector.indexOf(',') !== -1) {
if (Selector.hasTopLevelComma(selector)) {
throw new Error(`Selector cannot contain commas: ${selector}`);
}
if (!Selector.isValid(selector)) {
Expand Down
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