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import { LocaleOptions, WeekStartOptions } from '../types.ts'import toDate from '../toDate/index.ts'import toInteger from '../_lib/toInteger/index.ts'import requiredArgs from '../_lib/requiredArgs/index.ts'
/** * @name startOfWeek * @category Week Helpers * @summary Return the start of a week for the given date. * * @description * Return the start of a week for the given date. * The result will be in the local timezone. * * ### 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). * * @param {Date|Number} date - the original 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) * @returns {Date} the start of a week * @throws {TypeError} 1 argument required * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6 * * @example * // The start of a week for 2 September 2014 11:55:00: * const result = startOfWeek(new Date(2014, 8, 2, 11, 55, 0)) * //=> Sun Aug 31 2014 00:00:00 * * @example * // If the week starts on Monday, the start of the week for 2 September 2014 11:55:00: * const result = startOfWeek(new Date(2014, 8, 2, 11, 55, 0), { weekStartsOn: 1 }) * //=> Mon Sep 01 2014 00:00:00 */export default function startOfWeek(  dirtyDate: Date | number,  dirtyOptions?: LocaleOptions & WeekStartOptions): Date {  requiredArgs(1, arguments)
  const options = dirtyOptions || {}  const locale = options.locale  const localeWeekStartsOn =    locale && locale.options && locale.options.weekStartsOn  const defaultWeekStartsOn =    localeWeekStartsOn == null ? 0 : toInteger(localeWeekStartsOn)  const weekStartsOn =    options.weekStartsOn == null      ? defaultWeekStartsOn      : toInteger(options.weekStartsOn)
  // Test if weekStartsOn is between 0 and 6 _and_ is not NaN  if (!(weekStartsOn >= 0 && weekStartsOn <= 6)) {    throw new RangeError('weekStartsOn must be between 0 and 6 inclusively')  }
  const date = toDate(dirtyDate)  const day = date.getDay()  const diff = (day < weekStartsOn ? 7 : 0) + day - weekStartsOn
  date.setDate(date.getDate() - diff)  date.setHours(0, 0, 0, 0)  return date}