intervalEngulfsZoned

Signature

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

import { intervalEngulfsZoned } from "@northguild/gmt/zoned/interval";

Return true when interval B is fully contained within interval A — every instant of B

• falls within A.
• Uses Temporal.Instant.compare for comparison (via .toInstant()).
• Equivalent to 4-argument intervalContainsZoned(aStart, aEnd, bStart, bEnd).
• Returns false if either interval is invalid (start > end).
• Returns false on invalid input (wrong type, malformed strings, leap seconds).
• Accepts mixed calendar systems (E7’s D4-zoned, issue #152): both bare ISO zoned strings and GMT calendar-annotated ones ("5784-06-15T14:30:00-05:00[u-ca=hebrew][America/New_York]"), and the two endpoints need not agree on a calendar. Ordering is calendar-independent — verified that Temporal.Instant carries no calendar field at all and that Instant.compare/ZonedDateTime.compare both return 0 for the same instant expressed in hebrew, islamic-civil, japanese and iso8601.
• Still rejects Temporal’s own [timeZone][u-ca=...] RFC 9557 ordering, which reads GMT’s calendar-native digits as ISO digits — see regex/calendar-zoned-date-time.ts.

Parameters

Parameter	Type	Description
aStart	string	ISO 8601 zoned datetime string for the outer interval start
aEnd	string	ISO 8601 zoned datetime string for the outer interval end
bStart	string	ISO 8601 zoned datetime string for the inner interval start
bEnd	string	ISO 8601 zoned datetime string for the inner interval end

Returns

true if B is fully contained in A, or false on invalid input

Examples

intervalEngulfsZoned("2024-01-01T09:00:00+00:00[UTC]", "2024-12-31T17:00:00+00:00[UTC]", "2024-06-01T12:00:00+00:00[UTC]", "2024-07-01T13:00:00+00:00[UTC]") // true
intervalEngulfsZoned("2024-01-01T09:00:00+00:00[UTC]", "2024-12-31T17:00:00+00:00[UTC]", "2024-01-01T09:00:00+00:00[UTC]", "2024-12-31T17:00:00+00:00[UTC]") // true (equal intervals)
intervalEngulfsZoned("2024-01-01T09:00:00+00:00[UTC]", "2024-12-31T17:00:00+00:00[UTC]", "2024-01-01T09:00:00+00:00[UTC]", "2024-06-30T12:00:00+00:00[UTC]") // true
intervalEngulfsZoned("2024-06-01T12:00:00+00:00[UTC]", "2024-07-01T13:00:00+00:00[UTC]", "2024-01-01T09:00:00+00:00[UTC]", "2024-12-31T17:00:00+00:00[UTC]") // false
intervalEngulfsZoned("invalid", "2024-12-31T17:00:00+00:00[UTC]", "2024-06-01T12:00:00+00:00[UTC]", "2024-07-01T13:00:00+00:00[UTC]") // false

Source

zoned/interval/intervalEngulfsZoned.ts