intervalOverlappingDaysDate

Signature

intervalOverlappingDaysDate(aStart: string, aEnd: string, bStart: string, bEnd: string): number | null

Return how many distinct calendar dates two date intervals share.

• Half-open: an interval holds every date d with start <= d < end. The count is the number of days in the intersection [max(aStart, bStart), min(aEnd, bEnd)), that is min(aEnd, bEnd) - max(aStart, bStart) in days.
• Touching intervals (aEnd === bStart) share no day and count 0; so does an empty interval.
• Returns 0 when the intervals share no day (a well-defined answer, not invalid input).
• Returns null if either interval is invalid (start > end).
• Returns null on invalid input (wrong type, malformed strings).
• Accepts RFC 9557 calendar-annotated PlainDate strings — E5 (issue #78). All four arguments must name the same calendar (a bare ISO string names iso8601); different calendars return null, as Temporal’s until throws when CalendarEquals is false.
• Compatibility: before 1.16.0 arguments could name different calendars. 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 first interval start, optionally calendar-annotated
aEnd	string	ISO 8601 date string for the first interval end, optionally calendar-annotated
bStart	string	ISO 8601 date string for the second interval start, optionally calendar-annotated
bEnd	string	ISO 8601 date string for the second interval end, optionally calendar-annotated

Returns

number of shared calendar dates, 0 when disjoint, or null on invalid input

Examples

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

intervalOverlappingDaysDate("2024-01-01", "2024-06-30", "2024-04-01", "2024-12-31") // 90 (04-01 up to, not including, 06-30)

aStartaEndbStartbEnd

output

 

Source

plain/interval/intervalOverlappingDaysDate.ts