Temporal.ZonedDateTime.compare()

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 Temporal.ZonedDateTime.compare() static method returns a number (-1, 0, or 1) indicating whether the first date-time comes before, is the same as, or comes after the second date-time. It is equivalent to comparing the epochNanoseconds of the two datetimes.

Syntax

Temporal.ZonedDateTime.compare(dateTime1, dateTime2)

Parameters

dateTime1: A string, an object, or a Temporal.ZonedDateTime instance representing the first date-time to compare. It is converted to a Temporal.ZonedDateTime object using the same algorithm as Temporal.ZonedDateTime.from().
dateTime2: The second date-time to compare, converted to a Temporal.ZonedDateTime object using the same algorithm as dateTime1.

Return value

Returns -1 if dateTime1 comes before dateTime2, 0 if they are the same, and 1 if dateTime2 comes after. They are compared by their underlying instant values, ignoring their calendars or time zones.

Examples

Using Temporal.ZonedDateTime.compare()

const dt1 = Temporal.ZonedDateTime.from("2021-08-01T01:00:00[Europe/London]");
const dt2 = Temporal.ZonedDateTime.from("2021-08-02T00:00:00[Europe/London]");
console.log(Temporal.ZonedDateTime.compare(dt1, dt2)); // -1

const dt3 = Temporal.ZonedDateTime.from("2021-08-01T00:00:00[Europe/London]");
console.log(Temporal.ZonedDateTime.compare(dt1, dt3)); // 1

Sorting an array of date-times

The purpose of this compare() function is to act as a comparator to be passed to Array.prototype.sort() and related functions.

const dateTimes = [
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[America/New_York]"),
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[Asia/Hong_Kong]"),
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[Europe/London]"),
];

dateTimes.sort(Temporal.ZonedDateTime.compare);
console.log(dateTimes.map((d) => d.toString()));
// [ "2021-08-01T00:00:00+08:00[Asia/Hong_Kong]", "2021-08-01T00:00:00+01:00[Europe/London]", "2021-08-01T00:00:00-04:00[America/New_York]" ]

Note that they are compared by their instant values. In the very rare case where you want to compare them by their wall-clock times, convert them to PlainDateTime first.

const dateTimes = [
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[America/New_York]"),
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[Asia/Hong_Kong]"),
  Temporal.ZonedDateTime.from("2021-08-01T00:00:00[Europe/London]"),
];

dateTimes.sort((a, b) =>
  Temporal.PlainDateTime.compare(a.toPlainDateTime(), b.toPlainDateTime()),
);
console.log(dateTimes.map((d) => d.toString()));
// [ "2021-08-01T00:00:00-04:00[America/New_York]", "2021-08-01T00:00:00+08:00[Asia/Hong_Kong]", "2021-08-01T00:00:00+01:00[Europe/London]" ]

Specifications

Specification
Temporal proposal # sec-temporal.zoneddatetime.compare

Browser compatibility

	Desktop					Mobile						Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	Deno	Node.js
`compare`	No	No	No	No	No	No	No	No	No	No	No	1.40	No