| 12345678910111213141516171819202122232425262728293031323334353637 |
- import { getISOWeekYear } from "./getISOWeekYear.mjs";
- import { startOfISOWeek } from "./startOfISOWeek.mjs";
- import { constructFrom } from "./constructFrom.mjs";
- /**
- * @name startOfISOWeekYear
- * @category ISO Week-Numbering Year Helpers
- * @summary Return the start of an ISO week-numbering year for the given date.
- *
- * @description
- * Return the start 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
- *
- * @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 original date
- *
- * @returns The start of an ISO week-numbering year
- *
- * @example
- * // The start of an ISO week-numbering year for 2 July 2005:
- * const result = startOfISOWeekYear(new Date(2005, 6, 2))
- * //=> Mon Jan 03 2005 00:00:00
- */
- export function startOfISOWeekYear(date) {
- const year = getISOWeekYear(date);
- const fourthOfJanuary = constructFrom(date, 0);
- fourthOfJanuary.setFullYear(year, 0, 4);
- fourthOfJanuary.setHours(0, 0, 0, 0);
- return startOfISOWeek(fourthOfJanuary);
- }
- // Fallback for modularized imports:
- export default startOfISOWeekYear;
|