method Temporal.Calendar.prototype.monthCode Calendar.prototype.monthCode(date: | Temporal.PlainDate | Temporal.PlainDateTime | Temporal.PlainYearMonth | Temporal.PlainMonthDay | PlainDateLike | string): string Parameters date: | Temporal.PlainDate | Temporal.PlainDateTime | Temporal.PlainYearMonth | Temporal.PlainMonthDay | PlainDateLike | string Return Type string