Temporal.PlainDateTime.prototype.eraYear

The eraYear accessor property of {{jsxref("Temporal.PlainDateTime")}} instances returns a non-negative integer representing the year of this date within the era, or undefined if the calendar does not use eras (e.g., ISO 8601). The year index usually starts from 1 (more common) or 0, and years in an era can decrease with time (e.g., Gregorian BCE). era and eraYear together uniquely identify a year in a calendar, in the same way that year does. It is calendar-dependent.

The set accessor of eraYear is undefined. You cannot change this property directly. Use the {{jsxref("Temporal/PlainDateTime/with", "with()")}} method to create a new Temporal.PlainDateTime object with the desired new value.

For general information and more examples, see {{jsxref("Temporal/PlainDate/eraYear", "Temporal.PlainDate.prototype.eraYear")}}.

Examples#

Using eraYear#

const dt = Temporal.PlainDateTime.from("2021-07-01"); // ISO 8601 calendar
console.log(dt.eraYear); // undefined

const dt2 = Temporal.PlainDateTime.from("2021-07-01[u-ca=gregory]");
console.log(dt2.eraYear); // 2021

const dt3 = Temporal.PlainDateTime.from("-002021-07-01[u-ca=gregory]");
console.log(dt3.eraYear); // 2022; 0000 is used for the year 1 BC

const dt4 = Temporal.PlainDateTime.from("2021-07-01[u-ca=japanese]");
console.log(dt4.eraYear); // 3

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Temporal.PlainDateTime")}}
• {{jsxref("Temporal/PlainDateTime/with", "Temporal.PlainDateTime.prototype.with()")}}
• {{jsxref("Temporal/PlainDateTime/add", "Temporal.PlainDateTime.prototype.add()")}}
• {{jsxref("Temporal/PlainDateTime/subtract", "Temporal.PlainDateTime.prototype.subtract()")}}
• {{jsxref("Temporal/PlainDateTime/year", "Temporal.PlainDateTime.prototype.year")}}
• {{jsxref("Temporal/PlainDateTime/era", "Temporal.PlainDateTime.prototype.era")}}
• {{jsxref("Temporal/PlainDate/eraYear", "Temporal.PlainDate.prototype.eraYear")}}