JavaScript PlainMonthDay

The Temporal.PlainMonthDay object is a month and day object.

The Temporal.PlainMonthDay Object

The Temporal.PlainMonthDay object is a month and day object.

It represents the month and day of an ISO 8601 calendar, without a year or time.

Example: 05-17.

How to Create a PlainMonthDay Object

An PlainMonthDayTime object can be created in several different ways:

From	Code
Parameters	new Temporal.PlainMonthDay(param)
Object	Temporal.PlainMonthDay.from(object)
ISO/RFC 9557	Temporal.PlainMonthDay.from(RFC9557)

Create a PlainMonthDay with new

Example

Example Code

javascript

Try it Yourself

// Create a new PlainMonthDay object

const date = new Temporal.PlainMonthDay(5, 17);

PlainMonthDay from(object)

Example

Example Code

javascript

Try it Yourself

// Create a new PlainMonthDay object

const date = Temporal.PlainMonthDay.from({month:5, day:17});

PlainMonthDay from(RFC 9557)

Examples

Example Code

javascript

Try it Yourself

// Create a new PlainMonthDay object

const date = Temporal.PlainMonthDay.from("05-17");

Note that year is ignored if used as input

PlainMonthDay equals()

Example

Example Code

javascript

Try it Yourself

// Create two PlainMonthDay objects

const date1 = Temporal.PlainMonthDay.from("05-17");

const date2 = Temporal.PlainMonthDay.from("07-19");

// Compare

let result = date1.equals(date2);

Most (*) temporal objects have their own equals() method:

instant.equals(instant)
plaindate.equals(plaindate)
plaintime.equals(plaintime)
plainyearmonth.equals(plainyearmonth)
plainmonthday.equals(plainmonthday)
plaindateTime.equals(plaindatetime)
zoneddateTime.equals(zoneddtatime)

(*) Duration has not.

Learn More: > JavaScript Temporal Compare

The with() Method

The with() method returns a new PlainMonthDay object with specified field(s) replaced.

Example

Example Code

javascript

Try it Yourself

// Create a PlainMonthDay object

const date = Temporal.PlainMonthDay.from("05-17");

// Replace month

const newDate = date.with({ month:12 });

All PlainMonthDay Methods

Constructing	Description
from()	Creates a PlainMonthDay object from an object or a string
new (constructor)	Creates a PlainMonthDay object from integer parameters
Comparing
equals()	Returns true if two PlainMonthDay objects are identical
Converting
toPlainDate()	Returns a new PlainDate object
with()	Returns a new PlainMonthDay with specified fields modified
Formatting
toJSON()	Returns an RFC 9557 format string for JSON serialization
toLocaleString()	Returns a language-sensitive representation of the date
toString()	Returns an RFC 9557 format string representation of the date
valueOf()	TypeError (temporals cannot be converted to primitives)

All PlainMonthDay Properties

Property	Description
calendarID	Calendar system identifier ("iso8601")
day	The day as an integer (1-31)
monthCode	A calendar-specific string code for the month ("M01")

Note > The Temporal.PlainMonthDay object does not have a month property. > This is because non-ISO calendars (Hebrew, Chinese) can have leap months. > The same named month may have a different numerical index (month) each year, > making the month integer ambiguous without a year.

Display all PlainMonthDay Properties

Example Code

javascript

Try it Yourself

const date = new Temporal.PlainMonthDay(5, 17);