Temporal.PlainDate.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.PlainDate.compare() static method returns a number (-1, 0, or 1) indicating whether the first date comes before, is the same as, or comes after the second date. Equivalent to comparing the year, month, and day fields of the underlying ISO 8601 dates.

Syntax

js
Temporal.PlainDate.compare(date1, date2)

Parameters

date1

A string, an object, or a Temporal.PlainDate instance representing the first date to compare. It is converted to a Temporal.PlainDate object using the same algorithm as Temporal.PlainDate.from().

date2

The second date to compare, converted to a Temporal.PlainDate object using the same algorithm as date1.

Return value

Returns -1 if date1 comes before date2, 0 if they are the same, and 1 if date2 comes after. They are compared by their underlying date values, ignoring their calendars.

Examples

Using Temporal.PlainDate.compare()

js
const date1 = Temporal.PlainDate.from("2021-08-01");
const date2 = Temporal.PlainDate.from("2021-08-02");
console.log(Temporal.PlainDate.compare(date1, date2)); // -1

const date3 = Temporal.PlainDate.from("2021-07-31");
console.log(Temporal.PlainDate.compare(date1, date3)); // 1

Comparing dates in different calendars

js
const date1 = Temporal.PlainDate.from({ year: 2021, month: 8, day: 1 });
const date2 = Temporal.PlainDate.from({
  year: 2021,
  month: 8,
  day: 1,
  calendar: "islamic",
});
const date3 = Temporal.PlainDate.from({
  year: 2021,
  month: 8,
  day: 1,
  calendar: "hebrew",
});
console.log(date1.toString()); // "2021-08-01"
console.log(date2.toString()); // "2582-12-18[u-ca=islamic]"
console.log(date3.toString()); // "-001739-04-06[u-ca=hebrew]"
console.log(Temporal.PlainDate.compare(date1, date2)); // -1
console.log(Temporal.PlainDate.compare(date1, date3)); // 1

Sorting an array of dates

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

js
const dates = [
  Temporal.PlainDate.from({ year: 2021, month: 8, day: 1 }),
  Temporal.PlainDate.from({
    year: 2021,
    month: 8,
    day: 1,
    calendar: "islamic",
  }),
  Temporal.PlainDate.from({ year: 2021, month: 8, day: 1, calendar: "hebrew" }),
];

dates.sort(Temporal.PlainDate.compare);
console.log(dates.map((d) => d.toString()));
// [ "-001739-04-06[u-ca=hebrew]", "2021-08-01", "2582-12-18[u-ca=islamic]" ]

Specifications

Specification
Temporal proposal
# sec-temporal.plaindate.compare

Browser compatibility

BCD tables only load in the browser

See also