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- import { getDefaultOptions } from "./_lib/defaultOptions.js";
- import { constructFrom } from "./constructFrom.js";
- import { startOfWeek } from "./startOfWeek.js";
- import { toDate } from "./toDate.js";
- /**
- * The {@link getWeekYear} function options.
- */
- /**
- * @name getWeekYear
- * @category Week-Numbering Year Helpers
- * @summary Get the local week-numbering year of the given date.
- *
- * @description
- * Get the local week-numbering year of the given date.
- * 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
- *
- * @param date - The given date
- * @param options - An object with options.
- *
- * @returns The local week-numbering year
- *
- * @example
- * // Which week numbering year is 26 December 2004 with the default settings?
- * const result = getWeekYear(new Date(2004, 11, 26))
- * //=> 2005
- *
- * @example
- * // Which week numbering year is 26 December 2004 if week starts on Saturday?
- * const result = getWeekYear(new Date(2004, 11, 26), { weekStartsOn: 6 })
- * //=> 2004
- *
- * @example
- * // Which week numbering year is 26 December 2004 if the first week contains 4 January?
- * const result = getWeekYear(new Date(2004, 11, 26), { firstWeekContainsDate: 4 })
- * //=> 2004
- */
- export function getWeekYear(date, options) {
- const _date = toDate(date, options?.in);
- const year = _date.getFullYear();
- const defaultOptions = getDefaultOptions();
- const firstWeekContainsDate =
- options?.firstWeekContainsDate ??
- options?.locale?.options?.firstWeekContainsDate ??
- defaultOptions.firstWeekContainsDate ??
- defaultOptions.locale?.options?.firstWeekContainsDate ??
- 1;
- const firstWeekOfNextYear = constructFrom(options?.in || date, 0);
- firstWeekOfNextYear.setFullYear(year + 1, 0, firstWeekContainsDate);
- firstWeekOfNextYear.setHours(0, 0, 0, 0);
- const startOfNextYear = startOfWeek(firstWeekOfNextYear, options);
- const firstWeekOfThisYear = constructFrom(options?.in || date, 0);
- firstWeekOfThisYear.setFullYear(year, 0, firstWeekContainsDate);
- firstWeekOfThisYear.setHours(0, 0, 0, 0);
- const startOfThisYear = startOfWeek(firstWeekOfThisYear, options);
- if (+_date >= +startOfNextYear) {
- return year + 1;
- } else if (+_date >= +startOfThisYear) {
- return year;
- } else {
- return year - 1;
- }
- }
- // Fallback for modularized imports:
- export default getWeekYear;
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