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- import { getDefaultOptions } from "./_lib/defaultOptions.js";
- import { constructFrom } from "./constructFrom.js";
- import { getWeekYear } from "./getWeekYear.js";
- import { startOfWeek } from "./startOfWeek.js";
- /**
- * The {@link startOfWeekYear} function options.
- */
- /**
- * @name startOfWeekYear
- * @category Week-Numbering Year Helpers
- * @summary Return the start of a local week-numbering year for the given date.
- *
- * @description
- * Return the start of a local week-numbering year.
- * The exact calculation depends on the values of
- * `options.weekStartsOn` (which is the index of the first day of the week)
- * and `options.firstWeekContainsDate` (which is the day of January, which is always in
- * the first week of the week-numbering year)
- *
- * Week numbering: https://en.wikipedia.org/wiki/Week#The_ISO_week_date_system
- *
- * @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).
- * @typeParam ResultDate - The result `Date` type.
- *
- * @param date - The original date
- * @param options - An object with options
- *
- * @returns The start of a week-numbering year
- *
- * @example
- * // The start of an a week-numbering year for 2 July 2005 with default settings:
- * const result = startOfWeekYear(new Date(2005, 6, 2))
- * //=> Sun Dec 26 2004 00:00:00
- *
- * @example
- * // The start of a week-numbering year for 2 July 2005
- * // if Monday is the first day of week
- * // and 4 January is always in the first week of the year:
- * const result = startOfWeekYear(new Date(2005, 6, 2), {
- * weekStartsOn: 1,
- * firstWeekContainsDate: 4
- * })
- * //=> Mon Jan 03 2005 00:00:00
- */
- export function startOfWeekYear(date, options) {
- const defaultOptions = getDefaultOptions();
- const firstWeekContainsDate =
- options?.firstWeekContainsDate ??
- options?.locale?.options?.firstWeekContainsDate ??
- defaultOptions.firstWeekContainsDate ??
- defaultOptions.locale?.options?.firstWeekContainsDate ??
- 1;
- const year = getWeekYear(date, options);
- const firstWeek = constructFrom(options?.in || date, 0);
- firstWeek.setFullYear(year, 0, firstWeekContainsDate);
- firstWeek.setHours(0, 0, 0, 0);
- const _date = startOfWeek(firstWeek, options);
- return _date;
- }
- // Fallback for modularized imports:
- export default startOfWeekYear;
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