47 lines
1.7 KiB
JavaScript
47 lines
1.7 KiB
JavaScript
import { constructFrom } from "./constructFrom.js";
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import { getISOWeekYear } from "./getISOWeekYear.js";
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import { startOfISOWeek } from "./startOfISOWeek.js";
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/**
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* The {@link lastDayOfISOWeekYear} function options.
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*/
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/**
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* @name lastDayOfISOWeekYear
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* @category ISO Week-Numbering Year Helpers
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* @summary Return the last day of an ISO week-numbering year for the given date.
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*
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* @description
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* Return the last day of an ISO week-numbering year,
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* which always starts 3 days before the year's first Thursday.
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* The result will be in the local timezone.
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*
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* ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
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*
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* @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).
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* @typeParam ResultDate - The result `Date` type, it is the type returned from the context function if it is passed, or inferred from the arguments.
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*
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* @param date - The original date
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* @param options - An object with options
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*
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* @returns The end of an ISO week-numbering year
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*
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* @example
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* // The last day of an ISO week-numbering year for 2 July 2005:
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* const result = lastDayOfISOWeekYear(new Date(2005, 6, 2))
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* //=> Sun Jan 01 2006 00:00:00
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*/
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export function lastDayOfISOWeekYear(date, options) {
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const year = getISOWeekYear(date, options);
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const fourthOfJanuary = constructFrom(options?.in || date, 0);
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fourthOfJanuary.setFullYear(year + 1, 0, 4);
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fourthOfJanuary.setHours(0, 0, 0, 0);
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const date_ = startOfISOWeek(fourthOfJanuary, options);
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date_.setDate(date_.getDate() - 1);
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return date_;
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}
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// Fallback for modularized imports:
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export default lastDayOfISOWeekYear;
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