method Temporal.Calendar.prototype.dateAdd Calendar.prototype.dateAdd(date: Temporal.PlainDate | PlainDateLike | string,duration: Temporal.Duration | DurationLike | string,options?: ArithmeticOptions,): Temporal.PlainDate Parameters date: Temporal.PlainDate | PlainDateLike | string duration: Temporal.Duration | DurationLike | string optional options: ArithmeticOptions Return Type Temporal.PlainDate