The monthsInYear accessor property of Temporal.ZonedDateTime instances returns a positive integer representing the number of months in the year of this date. It is calendar-dependent.
The set accessor of monthsInYear is undefined. You cannot change this property directly.
For general information and more examples, see Temporal.PlainDate.prototype.monthsInYear.
const dt = Temporal.ZonedDateTime.from("2021-07-01[America/New_York]");
console.log(dt.monthsInYear); // 12Temporal.ZonedDateTimeTemporal.ZonedDateTime.prototype.with()Temporal.ZonedDateTime.prototype.add()Temporal.ZonedDateTime.prototype.subtract()Temporal.ZonedDateTime.prototype.yearTemporal.ZonedDateTime.prototype.monthTemporal.ZonedDateTime.prototype.monthCodeTemporal.ZonedDateTime.prototype.daysInMonthTemporal.PlainDate.prototype.monthsInYear