60 lines
1.9 KiB
JavaScript
60 lines
1.9 KiB
JavaScript
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"use strict";
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exports.getWeek = getWeek;
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var _index = require("./constants.js");
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var _index2 = require("./startOfWeek.js");
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var _index3 = require("./startOfWeekYear.js");
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var _index4 = require("./toDate.js");
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/**
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* The {@link getWeek} function options.
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*/
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/**
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* @name getWeek
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* @category Week Helpers
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* @summary Get the local week index of the given date.
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*
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* @description
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* Get the local week index of the given date.
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* The exact calculation depends on the values of
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* `options.weekStartsOn` (which is the index of the first day of the week)
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* and `options.firstWeekContainsDate` (which is the day of January, which is always in
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* the first week of the week-numbering year)
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*
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* Week numbering: https://en.wikipedia.org/wiki/Week#The_ISO_week_date_system
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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 date - The given date
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* @param options - An object with options
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*
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* @returns The week
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*
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* @example
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* // Which week of the local week numbering year is 2 January 2005 with default options?
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* const result = getWeek(new Date(2005, 0, 2))
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* //=> 2
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*
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* @example
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* // Which week of the local week numbering year is 2 January 2005,
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* // if Monday is the first day of the week,
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* // and the first week of the year always contains 4 January?
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* const result = getWeek(new Date(2005, 0, 2), {
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* weekStartsOn: 1,
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* firstWeekContainsDate: 4
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* })
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* //=> 53
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*/
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function getWeek(date, options) {
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const _date = (0, _index4.toDate)(date);
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const diff =
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+(0, _index2.startOfWeek)(_date, options) -
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+(0, _index3.startOfWeekYear)(_date, options);
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// Round the number of weeks to the nearest integer because the number of
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// milliseconds in a week 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(diff / _index.millisecondsInWeek) + 1;
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}
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