interval

A half-open [start, end) range of PlainDate, PlainDateTime, ZonedDateTime, or Instant values, plus IntervalSet, a normalized set of ranges.

import { Interval, IntervalSet } from 'orasna';

const day = Temporal.PlainDateTime.from('2026-11-02T00:00');
const morning = Interval.of(day.with({ hour: 8 }), day.with({ hour: 12 }));
const lunch = Interval.of(day.with({ hour: 12 }), day.with({ hour: 13 }));

morning.overlaps(lunch); // false: adjacent intervals do not overlap
morning.abuts(lunch); // true
morning.contains(day.with({ hour: 12 })); // false: end is excluded
morning.union(lunch).intervals.length; // 1 (merged)
morning.duration(); // PT4H

const leave = Interval.fromInclusiveDates(Temporal.PlainDate.from('2026-11-02'), Temporal.PlainDate.from('2026-11-06'));
leave.duration(); // P5D
leave.lastDay(); // 2026-11-06: the inclusive end, for display
String(leave); // '2026-11-02/2026-11-07'
Interval.parse('2026-11-02/2026-11-07', 'PlainDate');

IntervalSet.from() sorts its intervals and merges any that overlap or touch. It supports contains, union, intersection, subtract, gaps(within), totalDuration(), and iteration. See the attendance recipe.