isZonedRelativeDay

Signature

isZonedRelativeDay(value: string, offsetDays: number): boolean

import { isZonedRelativeDay } from "@northguild/gmt/zoned/compare";

Return true when value’s local calendar day falls offsetDays days from

• today in value’s own IANA timeZone.
• Subsumes isZonedToday/isZonedYesterday/isZonedTomorrow: offsetDays: 0 is “today”, -1 is “yesterday”, 1 is “tomorrow”, and any other integer offset works the same way.
• “Today” is resolved in value’s own timeZone — no separate timeZone argument needed, since value already carries its IANA timeZone. This is the deterministic counterpart to isRelativeDay, which depends on the system clock and system timeZone: the same instant is “today” in Pacific/Apia and “yesterday” in Pacific/Niue, a 24-hour spread.
• offsetDays must be an integer; non-integer or non-finite values return false.
• Returns false if value is invalid.

Parameters

Parameter	Type	Description
value	string	ISO ZonedDateTime string
offsetDays	number	integer number of days from today in value’s own timeZone

Returns

true if value’s local day is exactly offsetDays days from today in its own timeZone, false on invalid input

Examples

isZonedRelativeDay("2024-03-15T10:00:00-04:00[America/New_York]", 0) // true, if today is 2024-03-15 in America/New_York
isZonedRelativeDay("2024-03-14T10:00:00-04:00[America/New_York]", -1) // true, if today is 2024-03-15 in America/New_York
isZonedRelativeDay("2024-03-15T10:00:00+13:00[Pacific/Apia]", 0) // true, when the same instant is "yesterday" in Pacific/Niue
isZonedRelativeDay("invalid", 0) // false

Source

zoned/compare/isZonedRelativeDay.ts