Repository: date-fns/date-fns
File: src/setWeekYear/index.ts (TypeScript)

Code before:
 * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
 * @param {1|2|3|4|5|6|7} [options.firstWeekContainsDate=1] - the day of January, which is always in the first week of the year
 * @returns {Date} the new date with the local week-numbering year set
 * @throws {TypeError} 2 arguments required
 * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
 * @throws {RangeError} `options.firstWeekContainsDate` must be between 1 and 7
 *
 * @example
 * // Set the local week-numbering year 2004 to 2 January 2010 with default options:
 * var result = setWeekYear(new Date(2010, 0, 2), 2004)
 * //=> Sat Jan 03 2004 00:00:00
 *
 * @example
 * // Set the local week-numbering year 2004 to 2 January 2010,
 * // if Monday is the first day of week
 * // and 4 January is always in the first week of the year:
 * var result = setWeekYear(new Date(2010, 0, 2), 2004, {
 *   weekStartsOn: 1,
 *   firstWeekContainsDate: 4
 * })
 * //=> Sat Jan 01 2005 00:00:00
 */
export default function setWeekYear(
    dirtyDate: Date | number,
    dirtyWeekYear: number,
    dirtyOptions?: LocaleOptions & WeekStartOptions & WeekYearStartOptions,
): Date {
  requiredArgs(2, arguments)

  const options = dirtyOptions || {}
  const locale = options.locale
  const localeFirstWeekContainsDate =
    locale && locale.options && locale.options.firstWeekContainsDate
  const defaultFirstWeekContainsDate =
    localeFirstWeekContainsDate == null
      ? 1
      : toInteger(localeFirstWeekContainsDate)
  const firstWeekContainsDate =
    options.firstWeekContainsDate == null
      ? defaultFirstWeekContainsDate
      : toInteger(options.firstWeekContainsDate)

  let date = toDate(dirtyDate)
  const weekYear = toInteger(dirtyWeekYear)
  const diff = differenceInCalendarDays(date, startOfWeekYear(date, dirtyOptions))
  const firstWeek = new Date(0)
  firstWeek.setFullYear(weekYear, 0, firstWeekContainsDate)
  firstWeek.setHours(0, 0, 0, 0)
  date = startOfWeekYear(firstWeek, dirtyOptions)
  date.setDate(date.getDate() + diff)
  return date

Review comment (suggestion):
```suggestion
    options: LocaleOptions & WeekStartOptions & WeekYearStartOptions = {},
```

Code after:
 * @param {Date|Number} date - the date to be changed
 * @param {Number} weekYear - the local week-numbering year of the new date
 * @param {Object} [options] - an object with options.
 * @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
 * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
 * @param {1|2|3|4|5|6|7} [options.firstWeekContainsDate=1] - the day of January, which is always in the first week of the year
 * @returns {Date} the new date with the local week-numbering year set
 * @throws {TypeError} 2 arguments required
 * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
 * @throws {RangeError} `options.firstWeekContainsDate` must be between 1 and 7
 *
 * @example
 * // Set the local week-numbering year 2004 to 2 January 2010 with default options:
 * var result = setWeekYear(new Date(2010, 0, 2), 2004)
 * //=> Sat Jan 03 2004 00:00:00
 *
 * @example
 * // Set the local week-numbering year 2004 to 2 January 2010,
 * // if Monday is the first day of week
 * // and 4 January is always in the first week of the year:
 * var result = setWeekYear(new Date(2010, 0, 2), 2004, {
 *   weekStartsOn: 1,
 *   firstWeekContainsDate: 4
 * })
 * //=> Sat Jan 01 2005 00:00:00
 */
export default function setWeekYear(
  dirtyDate: Date | number,
  dirtyWeekYear: number,
  options: LocaleOptions & WeekStartOptions & FirstWeekContainsDateOptions = {}
): Date {
  requiredArgs(2, arguments)

  const locale = options.locale
  const localeFirstWeekContainsDate =
    locale && locale.options && locale.options.firstWeekContainsDate
  const defaultFirstWeekContainsDate =
    localeFirstWeekContainsDate == null
      ? 1
      : toInteger(localeFirstWeekContainsDate)
  const firstWeekContainsDate =
    options.firstWeekContainsDate == null
      ? defaultFirstWeekContainsDate
      : toInteger(options.firstWeekContainsDate)

  let date = toDate(dirtyDate)
  const weekYear = toInteger(dirtyWeekYear)
  const diff = differenceInCalendarDays(date, startOfWeekYear(date, options))
  const firstWeek = new Date(0)
  firstWeek.setFullYear(weekYear, 0, firstWeekContainsDate)
  firstWeek.setHours(0, 0, 0, 0)