differenceInBusinessDays.mjs
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import { addDays } from "./addDays.mjs";
import { differenceInCalendarDays } from "./differenceInCalendarDays.mjs";
import { isSameDay } from "./isSameDay.mjs";
import { isValid } from "./isValid.mjs";
import { isWeekend } from "./isWeekend.mjs";
import { toDate } from "./toDate.mjs";
/**
* @name differenceInBusinessDays
* @category Day Helpers
* @summary Get the number of business days between the given dates.
*
* @description
* Get the number of business day periods between the given dates.
* Business days being days that arent in the weekend.
* Like `differenceInCalendarDays`, the function removes the times from
* the dates before calculating the difference.
*
* @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 business days
*
* @example
* // How many business days are between
* // 10 January 2014 and 20 July 2014?
* const result = differenceInBusinessDays(
* new Date(2014, 6, 20),
* new Date(2014, 0, 10)
* )
* //=> 136
*
* // How many business days are between
* // 30 November 2021 and 1 November 2021?
* const result = differenceInBusinessDays(
* new Date(2021, 10, 30),
* new Date(2021, 10, 1)
* )
* //=> 21
*
* // How many business days are between
* // 1 November 2021 and 1 December 2021?
* const result = differenceInBusinessDays(
* new Date(2021, 10, 1),
* new Date(2021, 11, 1)
* )
* //=> -22
*
* // How many business days are between
* // 1 November 2021 and 1 November 2021 ?
* const result = differenceInBusinessDays(
* new Date(2021, 10, 1),
* new Date(2021, 10, 1)
* )
* //=> 0
*/
export function differenceInBusinessDays(dateLeft, dateRight) {
const _dateLeft = toDate(dateLeft);
let _dateRight = toDate(dateRight);
if (!isValid(_dateLeft) || !isValid(_dateRight)) return NaN;
const calendarDifference = differenceInCalendarDays(_dateLeft, _dateRight);
const sign = calendarDifference < 0 ? -1 : 1;
const weeks = Math.trunc(calendarDifference / 7);
let result = weeks * 5;
_dateRight = addDays(_dateRight, weeks * 7);
// the loop below will run at most 6 times to account for the remaining days that don't makeup a full week
while (!isSameDay(_dateLeft, _dateRight)) {
// sign is used to account for both negative and positive differences
result += isWeekend(_dateRight) ? 0 : sign;
_dateRight = addDays(_dateRight, sign);
}
// Prevent negative zero
return result === 0 ? 0 : result;
}
// Fallback for modularized imports:
export default differenceInBusinessDays;