The month accessor property of Temporal.PlainYearMonth instances returns a positive integer representing the 1-based month index in the year of this year-month. The first month of this year is 1, and the last month is the monthsInYear. It is calendar-dependent.
The set accessor of month is undefined. You cannot change this property directly. Use the with() method to create a new Temporal.PlainYearMonth object with the desired new value.
For general information and more examples, see Temporal.PlainDate.prototype.month.
const ym = Temporal.PlainYearMonth.from("2021-07"); // ISO 8601 calendar
console.log(ym.monthCode); // "M07"
console.log(ym.month); // 7Temporal.PlainYearMonthTemporal.PlainYearMonth.prototype.with()Temporal.PlainYearMonth.prototype.add()Temporal.PlainYearMonth.prototype.subtract()Temporal.PlainYearMonth.prototype.yearTemporal.PlainYearMonth.prototype.monthCodeTemporal.PlainYearMonth.prototype.daysInMonthTemporal.PlainYearMonth.prototype.monthsInYearTemporal.PlainDate.prototype.month