The dayOfYear accessor property of Temporal.ZonedDateTime instances returns a positive integer representing the 1-based day index in the year of this date. The first day of this year is 1, and the last day is the daysInYear. It is calendar-dependent.
The set accessor of dayOfYear is undefined. You cannot change this property directly. To create a new Temporal.ZonedDateTime object with the desired new dayOfYear value, use the add() or subtract() method with the appropriate number of days.
For general information and more examples, see Temporal.PlainDate.prototype.dayOfYear.
const dt = Temporal.ZonedDateTime.from("2021-07-01[America/New_York]");
console.log(dt.dayOfYear); // 182Temporal.ZonedDateTimeTemporal.ZonedDateTime.prototype.with()Temporal.ZonedDateTime.prototype.add()Temporal.ZonedDateTime.prototype.subtract()Temporal.ZonedDateTime.prototype.yearTemporal.ZonedDateTime.prototype.dayTemporal.ZonedDateTime.prototype.dayOfWeekTemporal.ZonedDateTime.prototype.daysInYearTemporal.PlainDate.prototype.dayOfYear