Temporal.Duration.prototype.add()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The add() method of Temporal.Duration instances returns a new Temporal.Duration object with the sum of this duration and a given duration. The result is balanced.

Syntax

js
add(other)

Parameters

other

A string, an object, or a Temporal.Duration instance representing a duration to add to this duration. It is converted to a Temporal.Duration object using the same algorithm as Temporal.Duration.from().

Return value

A new Temporal.Duration object representing the sum of this duration and other.

Exceptions

RangeError

Thrown in one of the following cases:

  • Either this or other is a calendar duration (it has a non-zero years, months, or weeks), because calendar durations are ambiguous without a calendar and time reference.
  • The sum of this and other overflows the maximum or underflows the minimum representable duration, which is ±253 seconds.

Description

Non-calendar durations unambiguously represent a fixed amount of time. Internally, this and other are both converted to nanoseconds (assuming 24-hour days) and added together. The result is then converted back to a Temporal.Duration object, so the result is always balanced or top-heavy with the largest possible unit being days.

If you want to perform addition or subtraction with a calendar duration, you can add both durations to a starting point and then figure out the difference between the two resulting instants; that is, dur1 + dur2 is equivalent to (start + dur1 + dur2) - start.

To add a duration to a date or time, use the add() method of the date or time object instead.

Examples

Using add()

js
const d1 = Temporal.Duration.from({ hours: 1, minutes: 30 });
const d2 = Temporal.Duration.from({ hours: -1, minutes: -20 });

const d3 = d1.add(d2);
console.log(d3.toString()); // "PT10M"

Adding calendar durations

js
const d1 = Temporal.Duration.from({ days: 1 });
const d2 = Temporal.Duration.from({ months: 1 });

d1.add(d2); // RangeError: for calendar duration arithmetic, use date arithmetic relative to a starting point

const start = Temporal.PlainDateTime.from("2022-01-01T00:00"); // ISO 8601 calendar
const result = start.add(d1).add(d2).since(start);
console.log(result.toString()); // "P32D"

Specifications

Specification
Temporal proposal
# sec-temporal.duration.prototype.add

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
add
Experimental

Legend

Tip: you can click/tap on a cell for more information.

No support
No support
Experimental. Expect behavior to change in the future.
See implementation notes.
User must explicitly enable this feature.

See also