previousBusinessDay

Signature

previousBusinessDay(value: string, calendar: BusinessCalendar): string

Return the last working day strictly before value.

• Strictly before: called on a working day it returns the previous one, never value itself. For the on-or-before behaviour — leave a working day alone, move a non-working one backward — use rollDate(value, "preceding", calendar).
• Equivalent to subtractBusinessDays(value, 1, calendar) for any valid calendar, but the calendar is required here: there is no Saturday–Sunday default to fall back on, because a weekend is never assumed.
• value may be any local date, working or not: being called from a weekend or a holiday is the normal case, not an error.
• value 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 "" when value is not a valid ISO PlainDate, when calendar is not a valid BusinessCalendar, and when the walk runs past 200,000 calendar days without finding a working day.

Parameters

Parameter	Type	Description
value	string	ISO PlainDate string to start from, excluded from the search
calendar	BusinessCalendar	BusinessCalendar naming the weekend days and holidays

Returns

ISO PlainDate string of the previous working day, or "" on invalid input

Related types

• BusinessCalendar

Examples

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

previousBusinessDay("2024-07-05", { weekend: [6, 7], holidays: ["2024-07-04"], timeZone: "America/New_York" }) // "2024-07-03" — skips the holiday

valuecalendar

output

 

Source

calendar/business/previousBusinessDay.ts