The toLocaleString() method of Temporal.Instant instances returns a string with a language-sensitive representation of this instant. In implementations with Intl.DateTimeFormat API support, this method delegates to Intl.DateTimeFormat.

The month accessor property of Temporal.PlainDate instances returns a positive integer representing the 1-based month index in the year of this date. The first month of this year is 1, and the last month is the monthsInYear. It is calendar-dependent.

The withCalendar() method of Temporal.PlainDateTime instances returns a new Temporal.PlainDateTime object representing this date-time interpreted in the new calendar system. Because all Temporal objects are designed to be immutable, this method essentially functions as the setter for the date-time's calendarId property.

The month accessor property of Temporal.ZonedDateTime instances returns a positive integer representing the 1-based month index in the year of this date. The first month of this year is 1, and the last month is the monthsInYear. It is calendar-dependent.

The eraYear accessor property of Temporal.ZonedDateTime 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 daysInWeek accessor property of Temporal.PlainDateTime instances returns a positive integer representing the number of days in the week of this date. It is calendar-dependent.

The Temporal.Instant.compare() static method returns a number (-1, 0, or 1) indicating whether the first instant comes before, is the same as, or comes after the second instant. It is equivalent to comparing the epochNanoseconds of the two instants.

The daysInMonth accessor property of Temporal.PlainDate instances returns a positive integer representing the number of days in the month of this date. It is calendar-dependent.

The inLeapYear accessor property of Temporal.PlainDateTime instances returns a boolean indicating whether this date is in a leap year. A leap year is a year that has more days (due to a leap day or leap month) than a common year. It is calendar-dependent.

The add() method of Temporal.Instant instances returns a new Temporal.Instant object representing this instant moved forward by a given duration (in a form convertible by Temporal.Duration.from()).