businessDaysBetween

Signature

businessDaysBetween(start: string, end: string, calendar: BusinessCalendar): number | null

Count the working days between two local dates, excluding start and including end.

• The convention is stated, not inferred: the range is (start, end]. Counting from Monday to Friday of the same week gives 4, not 5 — Monday itself is not counted.
• That makes it the inverse of addBusinessDays when n ≥ 0 or start is a business day: if end is addBusinessDays(start, n, calendar), this returns n. From a weekend or holiday start, a negative n counts one closer to zero, because start itself is excluded and is not a business day.
• end before start returns a negative count, so swapping the arguments negates the result. An empty range is always 0, never -0, and businessDaysBetween(d, d, calendar) is 0 for any d.
• The count is computed, not walked, so there is no range limit: whole weeks contribute one of each weekday and only the holidays are visited individually.
• Both dates and calendar.holidays are local dates; calendar.timeZone is not read. A caller holding an instant reduces it to a local date first, with floorToZone.
• Returns null when either date is not a valid ISO PlainDate, or calendar is not a valid BusinessCalendar. Narrow it with isValidBusinessCalendar to tell a misconfigured calendar apart from a genuine 0.

Parameters

Parameter	Type	Description
start	string	ISO PlainDate string, excluded from the count
end	string	ISO PlainDate string, included in the count
calendar	BusinessCalendar	BusinessCalendar naming the weekend days and holidays

Returns

number of working days in (start, end], negative when end precedes start, or null on invalid input

Related types

• BusinessCalendar

Examples

import { businessDaysBetween } from "@northguild/gmt/calendar/business";

businessDaysBetween("2024-07-01", "2024-07-05", { weekend: [6, 7], holidays: ["2024-07-04"], timeZone: "America/New_York" }) // 3 — Tue, Wed, Fri

startendcalendar

output

 

Source

calendar/business/businessDaysBetween.ts