59 lines
1.7 KiB
JavaScript
59 lines
1.7 KiB
JavaScript
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import { normalizeDates } from "./_lib/normalizeDates.js";
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import { compareAsc } from "./compareAsc.js";
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import { differenceInCalendarISOWeekYears } from "./differenceInCalendarISOWeekYears.js";
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import { subISOWeekYears } from "./subISOWeekYears.js";
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/**
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* The {@link differenceInISOWeekYears} function options.
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*/
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/**
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* @name differenceInISOWeekYears
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* @category ISO Week-Numbering Year Helpers
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* @summary Get the number of full ISO week-numbering years between the given dates.
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*
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* @description
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* Get the number of full ISO week-numbering years between the given dates.
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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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* @param laterDate - The later date
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* @param earlierDate - The earlier date
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* @param options - The options
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*
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* @returns The number of full ISO week-numbering years
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*
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* @example
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* // How many full ISO week-numbering years are between 1 January 2010 and 1 January 2012?
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* const result = differenceInISOWeekYears(
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* new Date(2012, 0, 1),
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* new Date(2010, 0, 1)
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* )
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* // => 1
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*/
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export function differenceInISOWeekYears(laterDate, earlierDate, options) {
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const [laterDate_, earlierDate_] = normalizeDates(
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options?.in,
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laterDate,
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earlierDate,
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);
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const sign = compareAsc(laterDate_, earlierDate_);
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const diff = Math.abs(
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differenceInCalendarISOWeekYears(laterDate_, earlierDate_, options),
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);
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const adjustedDate = subISOWeekYears(laterDate_, sign * diff, options);
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const isLastISOWeekYearNotFull = Number(
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compareAsc(adjustedDate, earlierDate_) === -sign,
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);
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const result = sign * (diff - isLastISOWeekYearNotFull);
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// Prevent negative zero
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return result === 0 ? 0 : result;
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}
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// Fallback for modularized imports:
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export default differenceInISOWeekYears;
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