Temporal.PlainYearMonth.prototype.toString()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The toString() method of Temporal.PlainYearMonth instances returns a string representing this year-month in the RFC 9557 format.

Syntax

js
toString()
toString(options)

Parameters

options Optional

An object containing the following property:

calendarName Optional

Whether to show the calendar annotation ([u-ca=calendar_id]) in the return value. Possible values are:

"auto" (default)

Include the calendar annotation if the calendar is not "iso8601". The reference day is included if the calendar is not "iso8601".

"always"

Always include the calendar annotation. The reference day is always included too.

"never"

Never include the calendar annotation. This makes the returned string not recoverable to the same Temporal.PlainYearMonth instance, although the year-month value still remains the same. The reference day is included if the calendar is not "iso8601".

"critical"

Always include the calendar annotation, and add a critical flag: [!u-ca=calendar_id]. Useful when sending the string to certain systems, but not useful for Temporal itself. The reference day is always included too.

Return value

A string in the RFC 9557 format representing this year-month. The calendar annotation is included as specified. The reference day is included if a calendar annotation is included or if the calendar is not "iso8601".

Exceptions

RangeError

Thrown if any of the options is invalid.

TypeError

Thrown if options is not an object or undefined.

Examples

Using toString()

js
const ym = Temporal.PlainYearMonth.from({ year: 2021, month: 8 });
console.log(ym.toString()); // '2021-08'

const ym2 = Temporal.PlainYearMonth.from({
  year: 4658,
  monthCode: "M08",
  calendar: "chinese",
});
console.log(ym2.toString()); // '2021-09-07[u-ca=chinese]'

Using options

js
const isoYM = Temporal.PlainYearMonth.from({ year: 2021, month: 8 });
const ym = Temporal.PlainYearMonth.from({
  year: 4658,
  monthCode: "M08",
  calendar: "chinese",
});
console.log(isoYM.toString({ calendarName: "auto" })); // '2021-08'
console.log(ym.toString({ calendarName: "auto" })); // '2021-09-07[u-ca=chinese]'
console.log(isoYM.toString({ calendarName: "always" })); // '2021-08-01[u-ca=iso8601]'
console.log(ym.toString({ calendarName: "always" })); // '2021-09-07[u-ca=chinese]'
console.log(isoYM.toString({ calendarName: "never" })); // '2021-08'
console.log(ym.toString({ calendarName: "never" })); // '2021-09-07'
console.log(isoYM.toString({ calendarName: "critical" })); // '2021-08-01[!u-ca=iso8601]'
console.log(ym.toString({ calendarName: "critical" })); // '2021-09-07[!u-ca=chinese]'

Specifications

Specification
Temporal proposal
# sec-temporal.plainyearmonth.prototype.tostring

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
toString
Experimental

Legend

Tip: you can click/tap on a cell for more information.

No support
No support
Experimental. Expect behavior to change in the future.
See implementation notes.
User must explicitly enable this feature.

See also