tiempo - Temporal API datetime utilities

Returns an array of ZonedDateTime objects for each calendar day within the interval. Each element represents the start of day (midnight) in the timezone of the interval start. The interval is inclusive of both start and end days.

Signature

function eachDayOfInterval(interval: {
  start: Temporal.Instant | Temporal.ZonedDateTime;
  end: Temporal.Instant | Temporal.ZonedDateTime;
}): Temporal.ZonedDateTime[]

Parameters

Parameter	Type	Description
`interval`	`{ start, end }`	The interval with start and end datetimes

Returns

Array of Temporal.ZonedDateTime at the start of each day in the interval.

For Instant inputs, UTC is used as the timezone. For ZonedDateTime inputs, the timezone of the start date is preserved.

Examples

Basic usage

import { eachDayOfInterval } from '@gobrand/tiempo';

const start = Temporal.ZonedDateTime.from('2025-01-06T10:00:00Z[UTC]');
const end = Temporal.ZonedDateTime.from('2025-01-10T14:00:00Z[UTC]');

const days = eachDayOfInterval({ start, end });
// [
//   2025-01-06T00:00:00Z[UTC],
//   2025-01-07T00:00:00Z[UTC],
//   2025-01-08T00:00:00Z[UTC],
//   2025-01-09T00:00:00Z[UTC],
//   2025-01-10T00:00:00Z[UTC]
// ]

With timezone

const start = Temporal.ZonedDateTime.from('2025-01-06T10:00:00-05:00[America/New_York]');
const end = Temporal.ZonedDateTime.from('2025-01-08T14:00:00-05:00[America/New_York]');

const days = eachDayOfInterval({ start, end });
// [
//   2025-01-06T00:00:00-05:00[America/New_York],
//   2025-01-07T00:00:00-05:00[America/New_York],
//   2025-01-08T00:00:00-05:00[America/New_York]
// ]

With Instant (uses UTC)

const start = Temporal.Instant.from('2025-01-06T00:00:00Z');
const end = Temporal.Instant.from('2025-01-08T00:00:00Z');

const days = eachDayOfInterval({ start, end });
// [
//   2025-01-06T00:00:00Z[UTC],
//   2025-01-07T00:00:00Z[UTC],
//   2025-01-08T00:00:00Z[UTC]
// ]

Single day interval

const date = Temporal.ZonedDateTime.from('2025-01-15T12:00:00Z[UTC]');

eachDayOfInterval({ start: date, end: date });
// [2025-01-15T00:00:00Z[UTC]]

Common Patterns

Build a calendar grid

import { eachDayOfInterval, startOfMonth, endOfMonth, startOfWeek, endOfWeek } from '@gobrand/tiempo';

function getCalendarDays(month: Temporal.ZonedDateTime) {
  const monthStart = startOfMonth(month);
  const monthEnd = endOfMonth(month);

  // Extend to full weeks for calendar grid
  const calendarStart = startOfWeek(monthStart);
  const calendarEnd = endOfWeek(monthEnd);

  return eachDayOfInterval({ start: calendarStart, end: calendarEnd });
}

Generate date range for availability

import { eachDayOfInterval, isSameDay } from '@gobrand/tiempo';

function getAvailableDays(
  rangeStart: Temporal.ZonedDateTime,
  rangeEnd: Temporal.ZonedDateTime,
  bookedDates: Temporal.ZonedDateTime[]
) {
  return eachDayOfInterval({ start: rangeStart, end: rangeEnd })
    .filter(day => !bookedDates.some(booked => isSameDay(day, booked)));
}

eachDayOfInterval

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