hugoWebsite/node_modules/date-fns/esm/lastDayOfISOWeekYear/index.js

35 lines
1.2 KiB
JavaScript

import getISOWeekYear from "../getISOWeekYear/index.js";
import startOfISOWeek from "../startOfISOWeek/index.js";
import requiredArgs from "../_lib/requiredArgs/index.js";
/**
* @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
*
* @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:
* const result = lastDayOfISOWeekYear(new Date(2005, 6, 2))
* //=> Sun Jan 01 2006 00:00:00
*/
export default function lastDayOfISOWeekYear(dirtyDate) {
requiredArgs(1, arguments);
var year = getISOWeekYear(dirtyDate);
var fourthOfJanuary = new Date(0);
fourthOfJanuary.setFullYear(year + 1, 0, 4);
fourthOfJanuary.setHours(0, 0, 0, 0);
var date = startOfISOWeek(fourthOfJanuary);
date.setDate(date.getDate() - 1);
return date;
}