timepiece/node_modules/date-fns/getISOWeekYear.mjs

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2024-05-14 14:54:12 +00:00
import { constructFrom } from "./constructFrom.mjs";
import { startOfISOWeek } from "./startOfISOWeek.mjs";
import { toDate } from "./toDate.mjs";
/**
* @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
*
* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
*
* @param date - The given date
*
* @returns The ISO week-numbering year
*
* @example
* // Which ISO-week numbering year is 2 January 2005?
* const result = getISOWeekYear(new Date(2005, 0, 2))
* //=> 2004
*/
export function getISOWeekYear(date) {
const _date = toDate(date);
const year = _date.getFullYear();
const fourthOfJanuaryOfNextYear = constructFrom(date, 0);
fourthOfJanuaryOfNextYear.setFullYear(year + 1, 0, 4);
fourthOfJanuaryOfNextYear.setHours(0, 0, 0, 0);
const startOfNextYear = startOfISOWeek(fourthOfJanuaryOfNextYear);
const fourthOfJanuaryOfThisYear = constructFrom(date, 0);
fourthOfJanuaryOfThisYear.setFullYear(year, 0, 4);
fourthOfJanuaryOfThisYear.setHours(0, 0, 0, 0);
const startOfThisYear = startOfISOWeek(fourthOfJanuaryOfThisYear);
if (_date.getTime() >= startOfNextYear.getTime()) {
return year + 1;
} else if (_date.getTime() >= startOfThisYear.getTime()) {
return year;
} else {
return year - 1;
}
}
// Fallback for modularized imports:
export default getISOWeekYear;