@stylistic/stylelint-plugin/lib/utils/matchesStringOrRegExp/index.js

A collection of stylistic/formatting Stylelint rules

/**
 * Compares a string to a second value that, if it fits a certain convention,
 * is converted to a regular expression before the comparison.
 * If it doesn't fit the convention, then two strings are compared.
 *
 * Any strings starting and ending with `/` are interpreted
 * as regular expressions.
 *
 * @param {string | Array<string>} input
 * @param {string | RegExp | Array<string | RegExp>} comparison
 *
 * @returns {false | {match: string, pattern: (string | RegExp), substring: string}}
 */
export function matchesStringOrRegExp (input, comparison) {
	if (!Array.isArray(input)) {
		return testAgainstStringOrRegExpOrArray(input, comparison)
	}

	for (let inputItem of input) {
		let testResult = testAgainstStringOrRegExpOrArray(inputItem, comparison)

		if (testResult) {
			return testResult
		}
	}

	return false
}

/**
 * @param {string} value
 * @param {string | RegExp | Array<string | RegExp>} comparison
 */
function testAgainstStringOrRegExpOrArray (value, comparison) {
	if (!Array.isArray(comparison)) {
		return testAgainstStringOrRegExp(value, comparison)
	}

	for (let comparisonItem of comparison) {
		let testResult = testAgainstStringOrRegExp(value, comparisonItem)

		if (testResult) {
			return testResult
		}
	}

	return false
}

/**
 * @param {string} value
 * @param {string | RegExp} comparison
 */
function testAgainstStringOrRegExp (value, comparison) {
	// If it's a RegExp, test directly
	if (comparison instanceof RegExp) {
		let match = value.match(comparison)

		return match ? { match: value, pattern: comparison, substring: match[0] || `` } : false
	}

	// Check if it's RegExp in a string
	let firstComparisonChar = comparison[0]
	let lastComparisonChar = comparison[comparison.length - 1]
	let secondToLastComparisonChar = comparison[comparison.length - 2]

	let comparisonIsRegex = firstComparisonChar === `/` && (lastComparisonChar === `/` || (secondToLastComparisonChar === `/` && lastComparisonChar === `i`))

	let hasCaseInsensitiveFlag = comparisonIsRegex && lastComparisonChar === `i`

	// If so, create a new RegExp from it
	if (comparisonIsRegex) {
		let valueMatch = hasCaseInsensitiveFlag ? value.match(new RegExp(comparison.slice(1, -2), `i`)) : value.match(new RegExp(comparison.slice(1, -1)))

		return valueMatch ? { match: value, pattern: comparison, substring: valueMatch[0] || `` } : false
	}

	// Otherwise, it's a string. Do a strict comparison
	return value === comparison ? { match: value, pattern: comparison, substring: value } : false
}