intervalEngulfsDate

Signature

intervalEngulfsDate(aStart: string, aEnd: string, bStart: string, bEnd: string): boolean

Return true when the half-open interval B [bStart, bEnd) lies within the half-open interval A [aStart, aEnd) — every day of B is also in A.

• Half-open: an interval holds every t with start <= t < end. B may start at A’s start and end at A’s end, because neither end is part of either interval.
• B must also overlap A, so an empty B (bStart === bEnd) counts only strictly inside A, never at an edge (CORE-6’s clampInterval clamps it away there).
• Equivalent to 4-argument intervalContainsDate(aStart, aEnd, bStart, bEnd).
• Uses Temporal.PlainDate.compare for comparison.
• Returns false if either interval is invalid (start > end).
• Returns false on invalid input (wrong type, malformed strings).
• Accepts RFC 9557 calendar-annotated PlainDate strings — E5 (issue #78). Ordering is calendar-independent, so arguments may carry different or no calendar tags (D4).
• Compatibility: since 1.16.0 calendar strings are RFC 9557 (ISO digits, [u-ca=<id>], canonical calendar ids); see isValidCalendarDate.

Parameters

Parameter	Type	Description
aStart	string	ISO 8601 date string for the outer interval start, optionally calendar-annotated
aEnd	string	ISO 8601 date string for the outer interval end (excluded), optionally calendar-annotated
bStart	string	ISO 8601 date string for the inner interval start, optionally calendar-annotated
bEnd	string	ISO 8601 date string for the inner interval end (excluded), optionally calendar-annotated

Returns

true if B lies within A, or false on invalid input

Examples

import { intervalEngulfsDate } from "@northguild/gmt/plain/interval";

intervalEngulfsDate("2024-01-01", "2024-12-31", "2024-06-01", "2024-07-01") // true

aStartaEndbStartbEnd

output

 

Source

plain/interval/intervalEngulfsDate.ts