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- import { getDefaultOptions } from "./_lib/defaultOptions.js";
- import { constructFrom } from "./constructFrom.js";
- import { differenceInCalendarDays } from "./differenceInCalendarDays.js";
- import { startOfWeekYear } from "./startOfWeekYear.js";
- import { toDate } from "./toDate.js";
- /**
- * The {@link setWeekYear} function options.
- */
- /**
- * @name setWeekYear
- * @category Week-Numbering Year Helpers
- * @summary Set the local week-numbering year to the given date.
- *
- * @description
- * Set the local week-numbering year to the given date,
- * saving the week number and the weekday number.
- * 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, it is the type returned from the context function if it is passed, or inferred from the arguments.
- *
- * @param date - The date to be changed
- * @param weekYear - The local week-numbering year of the new date
- * @param options - An object with options
- *
- * @returns The new date with the local week-numbering year set
- *
- * @example
- * // Set the local week-numbering year 2004 to 2 January 2010 with default options:
- * const result = setWeekYear(new Date(2010, 0, 2), 2004)
- * //=> Sat Jan 03 2004 00:00:00
- *
- * @example
- * // Set the local week-numbering year 2004 to 2 January 2010,
- * // if Monday is the first day of week
- * // and 4 January is always in the first week of the year:
- * const result = setWeekYear(new Date(2010, 0, 2), 2004, {
- * weekStartsOn: 1,
- * firstWeekContainsDate: 4
- * })
- * //=> Sat Jan 01 2005 00:00:00
- */
- export function setWeekYear(date, weekYear, options) {
- const defaultOptions = getDefaultOptions();
- const firstWeekContainsDate =
- options?.firstWeekContainsDate ??
- options?.locale?.options?.firstWeekContainsDate ??
- defaultOptions.firstWeekContainsDate ??
- defaultOptions.locale?.options?.firstWeekContainsDate ??
- 1;
- const diff = differenceInCalendarDays(
- toDate(date, options?.in),
- startOfWeekYear(date, options),
- options,
- );
- const firstWeek = constructFrom(options?.in || date, 0);
- firstWeek.setFullYear(weekYear, 0, firstWeekContainsDate);
- firstWeek.setHours(0, 0, 0, 0);
- const date_ = startOfWeekYear(firstWeek, options);
- date_.setDate(date_.getDate() + diff);
- return date_;
- }
- // Fallback for modularized imports:
- export default setWeekYear;
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