Temporal.PlainDate.prototype.dayOfWeek

Limited availability

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

See full compatibility

The dayOfWeek accessor property of Temporal.PlainDate instances returns a positive integer representing the 1-based day index in the week of this date. Days in a week are numbered sequentially from 1 to daysInWeek, with each number mapping to its name. It is calendar-dependent. 1 usually represents Monday in the calendar, even when locales using the calendar may consider a different day as the first day of the week (see Intl.Locale.prototype.getWeekInfo()).

All commonly supported calendars use 7-day weeks, and you could generally expect this property to return the same value for the same date across different calendars.

The set accessor of dayOfWeek is undefined. You cannot change this property directly. To create a new Temporal.PlainDate object with the desired new dayOfWeek value, use the add() or subtract() method with the appropriate number of days.

Examples

Using dayOfWeek

const date = Temporal.PlainDate.from("2021-07-01");
console.log(date.dayOfWeek); // 4; Thursday

const date2 = Temporal.PlainDate.from("2021-07-01[u-ca=chinese]");
console.log(date2.dayOfWeek); // 4

Changing dayOfWeek

PlainDate does not support changing dayOfWeek directly. To change the day of the week, you need to first figure out the difference in days to your desired day of the week, then use add or subtract to adjust the date accordingly. For example, to change to the Friday of this week (whether before or after):

function getDayInSameWeek(date, destDayOfWeek) {
  return date.add({ days: destDayOfWeek - date.dayOfWeek });
}

console.log(
  getDayInSameWeek(Temporal.PlainDate.from("2021-07-01"), 5).toString(),
); // 2021-07-02
console.log(
  getDayInSameWeek(Temporal.PlainDate.from("2021-07-03"), 5).toString(),
); // 2021-07-02

To change to the next Friday:

function getNextDayInWeek(date, destDayOfWeek) {
  const distance = destDayOfWeek - date.dayOfWeek;
  return date.add({
    days: distance < 0 ? date.daysInWeek + distance : distance,
  });
}

console.log(
  getNextDayInWeek(Temporal.PlainDate.from("2021-07-01"), 5).toString(),
); // 2021-07-02
console.log(
  getNextDayInWeek(Temporal.PlainDate.from("2021-07-03"), 5).toString(),
); // 2021-07-09

To change to the previous Friday:

function getPreviousDayInWeek(date, destDayOfWeek) {
  const distance = date.dayOfWeek - destDayOfWeek;
  return date.subtract({
    days: distance < 0 ? date.daysInWeek + distance : distance,
  });
}

console.log(
  getPreviousDayInWeek(Temporal.PlainDate.from("2021-07-01"), 5).toString(),
); // 2021-06-25
console.log(
  getPreviousDayInWeek(Temporal.PlainDate.from("2021-07-03"), 5).toString(),
); // 2021-07-02

Specifications

Specification
Temporal # sec-get-temporal.plaindate.prototype.dayofweek

Browser compatibility

	desktop					mobile							server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`dayOfWeek`	Chrome – Full support Chrome 144 (Release date: 2026-01-13) footnote Full support	Edge – Full support Edge 144 (Release date: 2026-01-21) footnote Full support	Firefox – Full support Firefox 139 (Release date: 2025-05-27) footnote Full support	Opera – Full support Opera 128 (Release date: 2026-02-26) footnote Full support	Safari – No support Safari footnote footnote See bug 223166	Chrome Android – Full support Chrome Android 144 (Release date: 2026-01-13) footnote Full support	Firefox for Android – Full support Firefox for Android 139 (Release date: 2025-05-27) footnote Full support	Opera Android – Full support Opera Android 95 (Release date: 2026-02-11) footnote Full support	Safari on iOS – No support Safari on iOS footnote footnote See bug 223166	Samsung Internet – No support Samsung Internet footnote No support	WebView Android – Full support WebView Android 144 (Release date: 2026-01-13) footnote Full support	WebView on iOS – No support WebView on iOS footnote footnote See bug 223166	Bun – No support Bun footnote No support	Deno – Full support Deno 2.7 (Release date: 2026-02-25) footnote Full support	Node.js – No support Node.js footnote No support

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

Full support: Full support
No support: No support
: See implementation notes.