stylelint/src/utils/findAtRuleContext.js

Modern CSS linter

/**
 * Find the at-rule in which a rule is nested.
 *
 * Returns `null` if the rule is not nested within an at-rule.
 *
 * @param {Rule} rule
 * @return {AtRule|null}
 */
export default function findAtRuleContext(rule) {
  const { parent } = rule
  if (parent.type === "root") { return null }
  if (parent.type === "atrule") {
    return parent
  }
  return findAtRuleContext(parent)
}