isBusinessDay

Signature

isBusinessDay(value: string, calendar?: BusinessCalendar): boolean

Return true when value is a working day in calendar.

calendar names the weekend days and holidays that make a date non-working. Omit it and GMT keeps its original fixed Monday–Friday week with no holidays.
Pass a calendar anywhere the weekend is not Saturday–Sunday. Much of the Middle East is Friday–Saturday and some markets keep a one-day weekend; the no-calendar form assumes Saturday–Sunday and is wrong for them.
value and calendar.holidays are local dates. calendar.timeZone is not read: it records which locality the calendar describes, so that a caller holding an instant knows which zone to reduce it in — with floorToZone or getZonedDateTimeFields — before asking this question.
Returns false if value is not a valid ISO PlainDate, or calendar is not a valid BusinessCalendar. Narrow a calendar first with isValidBusinessCalendar to tell a misconfigured calendar apart from a genuine non-working day. This is the locale-agnostic complement to the locale-aware isWeekend: isWeekend resolves weekend days per locale via Intl.Locale.prototype.weekInfo, whereas isBusinessDay uses the weekend the caller states, or Monday–Friday when they state none.

Parameter	Type	Description
`value`	`string`	ISO PlainDate string
`calendar`	`BusinessCalendar`	optional BusinessCalendar; defaults to Monday–Friday with no holidays

true if value is a working day, false on invalid input

import { isBusinessDay } from "@northguild/gmt/plain/compare";

isBusinessDay("2024-02-05") // true (Monday)