Temporal.ZonedDateTime.prototype.getTimeZoneTransition()

The getTimeZoneTransition() method of {{jsxref("Temporal.ZonedDateTime")}} instances returns a {{jsxref("Temporal.ZonedDateTime")}} object representing the closest instant after or before this instant at which the time zone's UTC offset changes (the returned instant is the first instant after the change), or null if there is no such transition. This is useful for finding out the offset rules of a time zone, such as its daylight saving time pattern.

Note that instants returned about the future may be unreliable, for example due to changes to the time zone definitions.

Syntax#

getTimeZoneTransition(direction)
getTimeZoneTransition(options)

Parameters#

• direction
• : A string representing the direction option. This is a convenience overload, so getTimeZoneTransition(direction) is equivalent to getTimeZoneTransition({ direction }), where direction is a string.
• options
• : An object containing the following property:
  • direction
  • : Whether to search before or after the current instant. Must be one of "next" or "previous".

Return value#

A {{jsxref("Temporal.ZonedDateTime")}} object with instant t, such that:

• The time zone offset at t is different from the offset one nanosecond before t.
• t < this.epochNanoseconds if direction is "previous", or t > this.epochNanoseconds if direction is "next".
• For all instants between this.epochNanoseconds and t, exclusive, the offset is constant.

If there is no such transition, null is returned.

Examples#

Finding the next time zone transition#

const dt = Temporal.ZonedDateTime.from("2024-01-01T00-05:00[America/New_York]");
const transition = dt.getTimeZoneTransition("next");
console.log(transition.toString()); // "2024-03-10T03:00:00-04:00[America/New_York]"

const transition2 = transition.getTimeZoneTransition("next");
console.log(transition2.toString()); // "2024-11-03T01:00:00-05:00[America/New_York]"

const transition3 = dt.getTimeZoneTransition("previous");
console.log(transition3.toString()); // "2023-11-05T01:00:00-05:00[America/New_York]"

const dt2 = Temporal.ZonedDateTime.from("2024-01-01T00Z[UTC]");
console.log(dt2.getTimeZoneTransition("next")); // null

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Temporal.ZonedDateTime")}}
• {{jsxref("Temporal/ZonedDateTime/with", "Temporal.ZonedDateTime.prototype.with()")}}
• {{jsxref("Temporal/ZonedDateTime/add", "Temporal.ZonedDateTime.prototype.add()")}}
• {{jsxref("Temporal/ZonedDateTime/subtract", "Temporal.ZonedDateTime.prototype.subtract()")}}
• {{jsxref("Temporal/ZonedDateTime/timeZoneId", "Temporal.ZonedDateTime.prototype.timeZoneId")}}
• {{jsxref("Temporal/ZonedDateTime/offset", "Temporal.ZonedDateTime.prototype.offset")}}