60 lines
2.0 KiB
JavaScript
60 lines
2.0 KiB
JavaScript
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import { millisecondsInWeek } from "./constants.mjs";
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import { startOfWeek } from "./startOfWeek.mjs";
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import { getTimezoneOffsetInMilliseconds } from "./_lib/getTimezoneOffsetInMilliseconds.mjs";
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/**
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* The {@link differenceInCalendarWeeks} function options.
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*/
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/**
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* @name differenceInCalendarWeeks
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* @category Week Helpers
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* @summary Get the number of calendar weeks between the given dates.
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*
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* @description
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* Get the number of calendar weeks between the given dates.
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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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*
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* @param dateLeft - The later date
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* @param dateRight - The earlier date
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* @param options - An object with options.
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*
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* @returns The number of calendar weeks
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*
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* @example
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* // How many calendar weeks are between 5 July 2014 and 20 July 2014?
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* const result = differenceInCalendarWeeks(
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* new Date(2014, 6, 20),
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* new Date(2014, 6, 5)
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* )
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* //=> 3
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*
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* @example
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* // If the week starts on Monday,
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* // how many calendar weeks are between 5 July 2014 and 20 July 2014?
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* const result = differenceInCalendarWeeks(
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* new Date(2014, 6, 20),
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* new Date(2014, 6, 5),
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* { weekStartsOn: 1 }
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* )
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* //=> 2
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*/
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export function differenceInCalendarWeeks(dateLeft, dateRight, options) {
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const startOfWeekLeft = startOfWeek(dateLeft, options);
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const startOfWeekRight = startOfWeek(dateRight, options);
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const timestampLeft =
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+startOfWeekLeft - getTimezoneOffsetInMilliseconds(startOfWeekLeft);
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const timestampRight =
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+startOfWeekRight - getTimezoneOffsetInMilliseconds(startOfWeekRight);
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// Round the number of days to the nearest integer because the number of
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// milliseconds in a days is not constant (e.g. it's different in the week of
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// the daylight saving time clock shift).
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return Math.round((timestampLeft - timestampRight) / millisecondsInWeek);
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}
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// Fallback for modularized imports:
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export default differenceInCalendarWeeks;
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