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 Temporal.PlainDateTime instance representing the first date-time to compare. It is converted to a Temporal.PlainDateTime object using the same algorithm as 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 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

Browser compatibility

See also

• Temporal.PlainDateTime
• Temporal.PlainDateTime.prototype.equals()