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- import { millisecondsInDay } from "./constants.mjs";
- import { startOfDay } from "./startOfDay.mjs";
- import { getTimezoneOffsetInMilliseconds } from "./_lib/getTimezoneOffsetInMilliseconds.mjs";
- /**
- * @name differenceInCalendarDays
- * @category Day Helpers
- * @summary Get the number of calendar days between the given dates.
- *
- * @description
- * Get the number of calendar days between the given dates. This means that the times are removed
- * from the dates and then the difference in days is calculated.
- *
- * @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 days
- *
- * @example
- * // How many calendar days are between
- * // 2 July 2011 23:00:00 and 2 July 2012 00:00:00?
- * const result = differenceInCalendarDays(
- * new Date(2012, 6, 2, 0, 0),
- * new Date(2011, 6, 2, 23, 0)
- * )
- * //=> 366
- * // How many calendar days are between
- * // 2 July 2011 23:59:00 and 3 July 2011 00:01:00?
- * const result = differenceInCalendarDays(
- * new Date(2011, 6, 3, 0, 1),
- * new Date(2011, 6, 2, 23, 59)
- * )
- * //=> 1
- */
- export function differenceInCalendarDays(dateLeft, dateRight) {
- const startOfDayLeft = startOfDay(dateLeft);
- const startOfDayRight = startOfDay(dateRight);
- const timestampLeft =
- +startOfDayLeft - getTimezoneOffsetInMilliseconds(startOfDayLeft);
- const timestampRight =
- +startOfDayRight - getTimezoneOffsetInMilliseconds(startOfDayRight);
- // Round the number of days to the nearest integer because the number of
- // milliseconds in a day is not constant (e.g. it's different in the week of
- // the daylight saving time clock shift).
- return Math.round((timestampLeft - timestampRight) / millisecondsInDay);
- }
- // Fallback for modularized imports:
- export default differenceInCalendarDays;
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