stylelint/lib/rules/value-keyword-case/index.mjs

A mighty CSS linter that helps you avoid errors and enforce conventions.

import valueParser from 'postcss-value-parser';

import {
	animationNameKeywords,
	animationShorthandKeywords,
	camelCaseKeywords,
	fontFamilyKeywords,
	fontShorthandKeywords,
	gridAreaKeywords,
	gridColumnKeywords,
	gridRowKeywords,
	listStyleShorthandKeywords,
	listStyleTypeKeywords,
	systemColorsKeywords,
} from '../../reference/keywords.mjs';
import { isBoolean, isRegExp, isString } from '../../utils/validateTypes.mjs';
import { declarationValueIndex } from '../../utils/nodeFieldIndices.mjs';
import getDeclarationValue from '../../utils/getDeclarationValue.mjs';
import getDimension from '../../utils/getDimension.mjs';
import isCounterIncrementCustomIdentValue from '../../utils/isCounterIncrementCustomIdentValue.mjs';
import isCounterResetCustomIdentValue from '../../utils/isCounterResetCustomIdentValue.mjs';
import isStandardSyntaxValue from '../../utils/isStandardSyntaxValue.mjs';
import optionsMatches from '../../utils/optionsMatches.mjs';
import report from '../../utils/report.mjs';
import ruleMessages from '../../utils/ruleMessages.mjs';
import validateOptions from '../../utils/validateOptions.mjs';

const ruleName = 'value-keyword-case';

const messages = ruleMessages(ruleName, {
	expected: (actual, expected) => `Expected "${actual}" to be "${expected}"`,
});

const meta = {
	url: 'https://stylelint.io/user-guide/rules/value-keyword-case',
	fixable: true,
};

// Operators are interpreted as "words" by the value parser, so we want to make sure to ignore them.
const ignoredCharacters = new Set(['+', '-', '/', '*', '%']);
const gridRowProps = new Set(['grid-row', 'grid-row-start', 'grid-row-end']);
const gridColumnProps = new Set(['grid-column', 'grid-column-start', 'grid-column-end']);

const mapLowercaseKeywordsToCamelCase = new Map();

for (const func of camelCaseKeywords) {
	mapLowercaseKeywordsToCamelCase.set(func.toLowerCase(), func);
}

/** @type {import('stylelint').CoreRules[ruleName]} */
const rule = (primary, secondaryOptions) => {
	return (root, result) => {
		const validOptions = validateOptions(
			result,
			ruleName,
			{
				actual: primary,
				possible: ['lower', 'upper'],
			},
			{
				actual: secondaryOptions,
				possible: {
					ignoreProperties: [isString, isRegExp],
					ignoreKeywords: [isString, isRegExp],
					ignoreFunctions: [isString, isRegExp],
					camelCaseSvgKeywords: [isBoolean],
				},
				optional: true,
			},
		);

		if (!validOptions) {
			return;
		}

		root.walkDecls((decl) => {
			const prop = decl.prop;
			const propLowerCase = decl.prop.toLowerCase();
			const value = decl.value;

			if (!isStandardSyntaxValue(value)) return;

			const parsed = valueParser(getDeclarationValue(decl));

			parsed.walk((node) => {
				const keyword = node.value;
				const valueLowerCase = keyword.toLowerCase();

				// Ignore system colors
				if (systemColorsKeywords.has(valueLowerCase)) {
					return;
				}

				// Ignore keywords within `url` and `var` function
				if (
					node.type === 'function' &&
					(valueLowerCase === 'url' ||
						valueLowerCase === 'var' ||
						valueLowerCase === 'counter' ||
						valueLowerCase === 'counters' ||
						valueLowerCase === 'attr')
				) {
					return false;
				}

				// ignore keywords within ignoreFunctions functions

				if (
					node.type === 'function' &&
					optionsMatches(secondaryOptions, 'ignoreFunctions', keyword)
				) {
					return false;
				}

				const { unit } = getDimension(node);

				// Ignore css variables, and hex values, and math operators, and sass interpolation
				if (
					node.type !== 'word' ||
					!isStandardSyntaxValue(keyword) ||
					value.includes('#') ||
					ignoredCharacters.has(keyword) ||
					unit
				) {
					return;
				}

				if (
					propLowerCase === 'animation' &&
					!animationShorthandKeywords.has(valueLowerCase) &&
					!animationNameKeywords.has(valueLowerCase)
				) {
					return;
				}

				if (propLowerCase === 'animation-name' && !animationNameKeywords.has(valueLowerCase)) {
					return;
				}

				if (
					propLowerCase === 'font' &&
					!fontShorthandKeywords.has(valueLowerCase) &&
					!fontFamilyKeywords.has(valueLowerCase)
				) {
					return;
				}

				if (propLowerCase === 'font-family' && !fontFamilyKeywords.has(valueLowerCase)) {
					return;
				}

				if (
					propLowerCase === 'counter-increment' &&
					isCounterIncrementCustomIdentValue(valueLowerCase)
				) {
					return;
				}

				if (propLowerCase === 'counter-reset' && isCounterResetCustomIdentValue(valueLowerCase)) {
					return;
				}

				if (gridRowProps.has(propLowerCase) && !gridRowKeywords.has(valueLowerCase)) {
					return;
				}

				if (gridColumnProps.has(propLowerCase) && !gridColumnKeywords.has(valueLowerCase)) {
					return;
				}

				if (propLowerCase === 'grid-area' && !gridAreaKeywords.has(valueLowerCase)) {
					return;
				}

				if (
					propLowerCase === 'list-style' &&
					!listStyleShorthandKeywords.has(valueLowerCase) &&
					!listStyleTypeKeywords.has(valueLowerCase)
				) {
					return;
				}

				if (propLowerCase === 'list-style-type' && !listStyleTypeKeywords.has(valueLowerCase)) {
					return;
				}

				if (optionsMatches(secondaryOptions, 'ignoreKeywords', keyword)) {
					return;
				}

				if (optionsMatches(secondaryOptions, 'ignoreProperties', prop)) {
					return;
				}

				const keywordLowerCase = keyword.toLocaleLowerCase();

				/** @type {string} */
				let expectedKeyword;

				/** @type {boolean} */
				const camelCaseSvgKeywords =
					(secondaryOptions && secondaryOptions.camelCaseSvgKeywords) || false;

				if (
					primary === 'lower' &&
					mapLowercaseKeywordsToCamelCase.has(keywordLowerCase) &&
					camelCaseSvgKeywords
				) {
					expectedKeyword = mapLowercaseKeywordsToCamelCase.get(keywordLowerCase);
				} else if (primary === 'lower') {
					expectedKeyword = keyword.toLowerCase();
				} else {
					expectedKeyword = keyword.toUpperCase();
				}

				if (keyword === expectedKeyword) {
					return;
				}

				const index = declarationValueIndex(decl) + node.sourceIndex;
				const endIndex = index + keyword.length;

				const fix = () => {
					node.value = expectedKeyword;
					decl.value = parsed.toString();
				};

				report({
					message: messages.expected,
					messageArgs: [keyword, expectedKeyword],
					node: decl,
					index,
					endIndex,
					result,
					ruleName,
					fix: {
						apply: fix,
						node: decl,
					},
				});
			});
		});
	};
};

rule.ruleName = ruleName;
rule.messages = messages;
rule.meta = meta;
export default rule;