50 lines
1.8 KiB
JavaScript
50 lines
1.8 KiB
JavaScript
"use strict";
|
|
exports.differenceInCalendarISOWeeks = differenceInCalendarISOWeeks;
|
|
var _index = require("./constants.js");
|
|
var _index2 = require("./startOfISOWeek.js");
|
|
var _index3 = require("./_lib/getTimezoneOffsetInMilliseconds.js");
|
|
|
|
/**
|
|
* @name differenceInCalendarISOWeeks
|
|
* @category ISO Week Helpers
|
|
* @summary Get the number of calendar ISO weeks between the given dates.
|
|
*
|
|
* @description
|
|
* Get the number of calendar ISO weeks between the given dates.
|
|
*
|
|
* ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
|
|
*
|
|
* @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).
|
|
*
|
|
* @param dateLeft - The later date
|
|
* @param dateRight - The earlier date
|
|
*
|
|
* @returns The number of calendar ISO weeks
|
|
*
|
|
* @example
|
|
* // How many calendar ISO weeks are between 6 July 2014 and 21 July 2014?
|
|
* const result = differenceInCalendarISOWeeks(
|
|
* new Date(2014, 6, 21),
|
|
* new Date(2014, 6, 6)
|
|
* )
|
|
* //=> 3
|
|
*/
|
|
function differenceInCalendarISOWeeks(dateLeft, dateRight) {
|
|
const startOfISOWeekLeft = (0, _index2.startOfISOWeek)(dateLeft);
|
|
const startOfISOWeekRight = (0, _index2.startOfISOWeek)(dateRight);
|
|
|
|
const timestampLeft =
|
|
+startOfISOWeekLeft -
|
|
(0, _index3.getTimezoneOffsetInMilliseconds)(startOfISOWeekLeft);
|
|
const timestampRight =
|
|
+startOfISOWeekRight -
|
|
(0, _index3.getTimezoneOffsetInMilliseconds)(startOfISOWeekRight);
|
|
|
|
// Round the number of weeks to the nearest integer because the number of
|
|
// milliseconds in a week is not constant (e.g. it's different in the week of
|
|
// the daylight saving time clock shift).
|
|
return Math.round(
|
|
(timestampLeft - timestampRight) / _index.millisecondsInWeek,
|
|
);
|
|
}
|