text: import toDate from "../toDate/index.js";
  import startOfISOWeek from "../startOfISOWeek/index.js";
  import requiredArgs from "../_lib/requiredArgs/index.js";
  /**
   * @name getISOWeekYear
   * @category ISO Week-Numbering Year Helpers
   * @summary Get the ISO week-numbering year of the given date.
   *
   * @description
   * Get the ISO week-numbering year of the given date,
   * which always starts 3 days before the year's first Thursday.
   *
   * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
   *
   * ### v2.0.0 breaking changes:
   *
   * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
   *
   * - The function was renamed from `getISOYear` to `getISOWeekYear`.
   *   "ISO week year" is short for [ISO week-numbering year](https://en.wikipedia.org/wiki/ISO_week_date).
   *   This change makes the name consistent with
   *   locale-dependent week-numbering year helpers, e.g., `getWeekYear`.
   *
   * @param {Date|Number} date - the given date
   * @returns {Number} the ISO week-numbering year
   * @throws {TypeError} 1 argument required
   *
   * @example
   * // Which ISO-week numbering year is 2 January 2005?
   * const result = getISOWeekYear(new Date(2005, 0, 2))
   * //=> 2004
   */
  
  export default function getISOWeekYear(dirtyDate) {
    requiredArgs(1, arguments);
    var date = toDate(dirtyDate);
    var year = date.getFullYear();
    var fourthOfJanuaryOfNextYear = new Date(0);
    fourthOfJanuaryOfNextYear.setFullYear(year + 1, 0, 4);
    fourthOfJanuaryOfNextYear.setHours(0, 0, 0, 0);
    var startOfNextYear = startOfISOWeek(fourthOfJanuaryOfNextYear);
    var fourthOfJanuaryOfThisYear = new Date(0);
    fourthOfJanuaryOfThisYear.setFullYear(year, 0, 4);
    fourthOfJanuaryOfThisYear.setHours(0, 0, 0, 0);
    var startOfThisYear = startOfISOWeek(fourthOfJanuaryOfThisYear);
  
    if (date.getTime() >= startOfNextYear.getTime()) {
      return year + 1;
    } else if (date.getTime() >= startOfThisYear.getTime()) {
      return year;
    } else {
      return year - 1;
    }
  }