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import getISOWeekYear from '../getISOWeekYear/index'
import startOfISOWeek from '../startOfISOWeek/index'
import requiredArgs from '../_lib/requiredArgs/index'
/**
* @name lastDayOfISOWeekYear
* @category ISO Week-Numbering Year Helpers
* @summary Return the last day of an ISO week-numbering year for the given date.
*
* @description
* Return the last day of an ISO week-numbering year,
* which always starts 3 days before the year's first Thursday.
* The result will be in the local timezone.
*
* 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 `lastDayOfISOYear` to `lastDayOfISOWeekYear`.
* "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 original date
* @returns {Date} the end of an ISO week-numbering year
* @throws {TypeError} 1 argument required
*
* @example
* // The last day of an ISO week-numbering year for 2 July 2005:
* var result = lastDayOfISOWeekYear(new Date(2005, 6, 2))
* //=> Sun Jan 01 2006 00:00:00
*/
export default function lastDayOfISOWeekYear(dirtyDate: Date | number): Date {
requiredArgs(1, arguments)
const year = getISOWeekYear(dirtyDate)
const fourthOfJanuary = new Date(0)
fourthOfJanuary.setFullYear(year + 1, 0, 4)
fourthOfJanuary.setHours(0, 0, 0, 0)
const date = startOfISOWeek(fourthOfJanuary)
date.setDate(date.getDate() - 1)
return date
}
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