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#74068 nth child specificity #369

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merged 7 commits into from
Nov 7, 2023
+89 −3
Merged

#74068 nth child specificity #369

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d519ee9
fix(): nth-child specificity
SStranks Nov 2, 2023
fc1db40
fix(selectorPrinting.test): added more tests
SStranks Nov 2, 2023
8d81e52
fix(selectorPrinting): complete
SStranks Nov 2, 2023
b99246f
fix(): comment formatting
SStranks Nov 3, 2023
c7b2ea9
fix(selectorPrinting): different logical approach
SStranks Nov 3, 2023
733bb34
chore(): tidying up
SStranks Nov 4, 2023
1bc7121
fix(selectorPrinting.ts): formatting
SStranks Nov 6, 2023
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24 changes: 22 additions & 2 deletions src/services/selectorPrinting.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -456,10 +456,9 @@ export class SelectorPrinting {
continue elementLoop;
}

if (text.match(/^:(?:nth-child|nth-last-child|host|host-context)/i) && childElements.length > 0) {
if (text.match(/^:(?:host|host-context)/i) && childElements.length > 0) {
// The specificity of :host() is that of a pseudo-class, plus the specificity of its argument.
// The specificity of :host-context() is that of a pseudo-class, plus the specificity of its argument.
// The specificity of an :nth-child() or :nth-last-child() selector is the specificity of the pseudo class itself (counting as one pseudo-class selector) plus the specificity of the most specific complex selector in its selector list argument.
specificity.attr++;

let mostSpecificListItem = calculateMostSpecificListItem(childElements);
Expand All @@ -470,6 +469,27 @@ export class SelectorPrinting {
continue elementLoop;
}

if (text.match(/^:(?:nth-child|nth-last-child)/i) && childElements.length > 0) {
/* The specificity of the :nth-child(An+B [of S]?) pseudo-class is the specificity of a single pseudo-class plus, if S is specified, the specificity of the most specific complex selector in S */
// https://www.w3.org/TR/selectors-4/#the-nth-child-pseudo
specificity.attr++;

const selectorText = text.slice(text.indexOf('(') + 1, text.length -1);

// Test for presence of complex-selector-list S; find highest specificity
const keyword = text.indexOf(' of ');
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Testing for a space before and after of is not clean. There could also be a tab, or even a non word character

ul.one > li:nth-child(-n + 3 of.noted) {
}

would be valid too.

I suggest to jeust use the scanner to find out if there's an of ident in the string.

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Reworked the logic in the latest commit. When the 'An + B [of S]?' syntax is respected then we can just grab the last childElement as it will contain the entire complex-selector list (S).

The edge case where 'n' has no integer prefix (the parser does not recognise it as a binary expression token). Extract out the complex-selector list, and re-parse the selectors. This also handles the different syntax possibilities; added more tests for completeness.

if (keyword !== -1) {
const psuedoSelector = element.getChildren();
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Typo - should be named 'pseudoSelector' (e/u inversion)

const complexSelectorList = psuedoSelector[psuedoSelector.length - 1].getChildren();
let mostSpecificListItem = calculateMostSpecificListItem(complexSelectorList);

specificity.id += mostSpecificListItem.id;
specificity.attr += mostSpecificListItem.attr;
specificity.tag += mostSpecificListItem.tag;
}
continue elementLoop;
}

specificity.attr++; //pseudo class
continue elementLoop;
}
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30 changes: 30 additions & 0 deletions src/test/css/selectorPrinting.test.ts
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Expand Up @@ -309,11 +309,41 @@ suite('CSS - MarkedStringPrinter selectors specificities', () => {
});

test('nth-child, nth-last-child specificity', function () {
assertSelectorMarkdown(p, '#foo:nth-child(2)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 1, 0)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(even)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 1, 0)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(odd)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 1, 0)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(-n + 2)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 1, 0)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(n of li)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 1, 1)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(-n+3 of li.important)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 2, 1)'
]);

assertSelectorMarkdown(p, '#foo:nth-child(-n+3 of li.important, .class1.class2.class3)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 4, 0)'
]);

assertSelectorMarkdown(p, '#foo:nth-last-child(-n+3 of li, .important)', '#foo', [
{ language: 'html', value: '<element id="foo" :nth-last-child>' },
'[Selector Specificity](https://developer.mozilla.org/docs/Web/CSS/Specificity): (1, 2, 0)'
Expand Down
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