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TemporalCalendar

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:208

A CalendarBackend over a Temporal implementation, computing in one named time zone. Build one with createTemporalCalendar.

Every method answers what the Date backend answers for the same inputs when the zone is the process’s own; see the module comment for the differences between Temporal and Date that are reproduced deliberately. The local methods answer NaN for an instant or a date the backend cannot represent and never throw; the four named-zone methods throw the runtime’s RangeError for a zone it does not know or an instant it cannot represent, which is the contract the interface states.

Implements

CalendarBackend

Constructors

Constructor

new TemporalCalendar(temporal, options?): TemporalCalendar;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:215

Parameters

Parameter	Type
`temporal`	`TemporalLike`
`options`	`TemporalCalendarOptions`

Returns

TemporalCalendar

Properties

timeZone

readonly timeZone: string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:210

The IANA zone every local answer is computed in, in its canonical spelling.

Methods

addDays()

addDays(epochMs, days): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:275

Move an instant by whole calendar days, holding the local wall-clock time. A day that contains a daylight-saving transition is 23 or 25 hours long, so this is a field step, not an addition of milliseconds.

Parameters

Parameter	Type
`epochMs`	`number`
`days`	`number`

Returns

number

Implementation of

CalendarBackend.addDays

addMonths()

addMonths(epochMs, months): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:282

Move an instant by whole calendar months, holding the local wall-clock time and clamping the day to the length of the month landed in: 31 January plus a month is 28 February, or 29 in a leap year, never 3 March.

Parameters

Parameter	Type
`epochMs`	`number`
`months`	`number`

Returns

number

Implementation of

CalendarBackend.addMonths

fields()

fields(epochMs): CalendarFields;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:243

The local calendar fields of an instant, weekday included. See CalendarFields.

Parameters

Parameter	Type
`epochMs`	`number`

Returns

CalendarFields

Implementation of

CalendarBackend.fields

fieldsInZone()

fieldsInZone(zone, epochMs): ZonedFields;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:389

The calendar date and wall-clock time a named IANA zone shows for an instant. Throws the runtime’s RangeError for a zone it does not know or an instant it cannot represent.

Parameters

Parameter	Type
`zone`	`string`
`epochMs`	`number`

Returns

ZonedFields

Implementation of

CalendarBackend.fieldsInZone

formatDateInZone()

formatDateInZone(zone, epochMs): string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:404

The calendar date in a named IANA zone, July 31, 2026, in the en-US style the timezone forms answer in. Throws the runtime’s RangeError for a zone it does not know or an instant it cannot represent.

Parameters

Parameter	Type
`zone`	`string`
`epochMs`	`number`

Returns

string

Implementation of

CalendarBackend.formatDateInZone

formatLongDate()

formatLongDate(epochMs, locale): string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:355

The spelled-out local date in a locale, Tuesday, March 10, 2026 in en.

Parameters

Parameter	Type
`epochMs`	`number`
`locale`	`string`

Returns

string

Implementation of

CalendarBackend.formatLongDate

formatTimeInZone()

formatTimeInZone(zone, epochMs): string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:400

The wall-clock time in a named IANA zone, 1:00 AM, in the en-US style the timezone forms answer in. Throws the runtime’s RangeError for a zone it does not know or an instant it cannot represent.

Parameters

Parameter	Type
`zone`	`string`
`epochMs`	`number`

Returns

string

Implementation of

CalendarBackend.formatTimeInZone

formatTimeOfDay()

formatTimeOfDay(epochMs, locale): string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:365

The local time of day in a locale, 9:30:00 AM in en.

Parameters

Parameter	Type
`epochMs`	`number`
`locale`	`string`

Returns

string

Implementation of

CalendarBackend.formatTimeOfDay

localMidnight()

localMidnight(
   year,
   month0,
   day
): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:259

Local midnight on a calendar date, in epoch milliseconds.

Fields overflow the way Date’s do (month 12 is January of the next year, day 0 the last day of the month before), which is what a caller checking for a rolled-over literal relies on: build the date, read its fields back, and a 30 February shows up as 1 or 2 March.

The year is taken as written, astronomically: 26 is 26 AD and 0 is 1 BC. The Date constructor’s reading of 0 to 99 as the 1900s is not part of the contract, because every year a caller passes is one read off a date or written out in full (#823). The same holds for localWallClock.

Parameters

Parameter	Type
`year`	`number`
`month0`	`number`
`day`	`number`

Returns

number

Implementation of

CalendarBackend.localMidnight

localWallClock()

localWallClock(
   year,
   month0,
   day,
   minutesPastMidnight
): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:263

A wall-clock time on a calendar date, given as minutes past local midnight, in epoch milliseconds.

The minutes name a clock reading, not an elapsed span: 540 minutes is 09:00 on that date even on a day with a daylight-saving transition, where 540 minutes of elapsed time from midnight would land at 10:00 or 08:00.

Parameters

Parameter	Type
`year`	`number`
`month0`	`number`
`day`	`number`
`minutesPastMidnight`	`number`

Returns

number

Implementation of

CalendarBackend.localWallClock

now()

now(): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:239

The current instant, in epoch milliseconds. Read at evaluation time, never baked into bytecode.

Returns

number

Implementation of

CalendarBackend.now

parseIso8601()

parseIso8601(text): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:308

Parse an ISO 8601 date or date-time string to epoch milliseconds, or NaN when it names no instant.

A date-only string (2019-04-01) is UTC midnight; a date-time with no offset and no Z is local time. Both readings are the ECMAScript ones, and every backend reproduces them so the two spellings of a literal keep meaning the same instant whichever backend is in use.

Parameters

Parameter	Type
`text`	`string`

Returns

number

Implementation of

CalendarBackend.parseIso8601

utcOffsetMinutes()

utcOffsetMinutes(epochMs): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:298

The local zone’s offset from UTC at an instant, in minutes, positive when ahead of UTC.

Parameters

Parameter	Type
`epochMs`	`number`

Returns

number

Implementation of

CalendarBackend.utcOffsetMinutes

zone()

zone(): string;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:396

The IANA zone this backend computes in, which is what CalendarBackend.zone documents.

Returns

string

Implementation of

CalendarBackend.zone

zoneOffsetMinutes()

zoneOffsetMinutes(zone, epochMs): number;

Defined in: packages/engine/src/temporal/TemporalCalendar.ts:375

A named IANA zone’s offset from UTC at an instant, in minutes, positive when ahead of UTC. Throws the runtime’s RangeError for a zone it does not know or an instant it cannot represent.

Parameters

Parameter	Type
`zone`	`string`
`epochMs`	`number`

Returns

number

Implementation of

CalendarBackend.zoneOffsetMinutes