Temporal.PlainDateTime.compare()

The Temporal.PlainDateTime.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. Equivalent to first comparing their dates, then comparing their times if the dates are the same.

Syntax#

Temporal.PlainDateTime.compare(dateTime1, dateTime2)

Parameters#

• dateTime1
• : A string, an object, or a {{jsxref("Temporal.PlainDateTime")}} instance representing the first date-time to compare. It is converted to a Temporal.PlainDateTime object using the same algorithm as {{jsxref("Temporal/PlainDateTime/from", "Temporal.PlainDateTime.from()")}}.
• dateTime2
• : The second date-time to compare, converted to a Temporal.PlainDateTime 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 dateTime1 comes after dateTime2. They are compared by their underlying date and time values, ignoring their calendars.

Examples#

Using Temporal.PlainDateTime.compare()#

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

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

Comparing dates in different calendars#

const dt1 = Temporal.PlainDateTime.from({ year: 2021, month: 8, day: 1 });
const dt2 = Temporal.PlainDateTime.from({
  year: 2021,
  month: 8,
  day: 1,
  calendar: "islamic-umalqura",
});
const dt3 = Temporal.PlainDateTime.from({
  year: 2021,
  month: 8,
  day: 1,
  calendar: "hebrew",
});
console.log(dt1.toString()); // "2021-08-01T00:00:00"
console.log(dt2.toString()); // "2582-12-17T00:00:00[u-ca=islamic-umalqura]"
console.log(dt3.toString()); // "-001739-04-06T00:00:00[u-ca=hebrew]"
console.log(Temporal.PlainDateTime.compare(dt1, dt2)); // -1
console.log(Temporal.PlainDateTime.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 {{jsxref("Array.prototype.sort()")}} and related functions.

const dateTimes = [
  Temporal.PlainDateTime.from("2021-08-01"),
  Temporal.PlainDateTime.from("2021-08-02"),
  Temporal.PlainDateTime.from("2021-08-01T01:00:00"),
];

dateTimes.sort(Temporal.PlainDateTime.compare);
console.log(dateTimes.map((d) => d.toString()));
// [ "2021-08-01T00:00:00", "2021-08-01T01:00:00", "2021-08-02T00:00:00" ]

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Temporal.PlainDateTime")}}
• {{jsxref("Temporal/PlainDateTime/equals", "Temporal.PlainDateTime.prototype.equals()")}}