Temporal.ZonedDateTime.prototype.equals()

The equals() method of Temporal.ZonedDateTime instances returns true if this date-time is equivalent in value to another date-time (in a form convertible by Temporal.ZonedDateTime.from()), and false otherwise. They are compared both by their instant values, time zones, and their calendars, so two date-times from different calendars or time zones may be considered equal by Temporal.ZonedDateTime.compare() but not by equals().

Syntax

equals(other)

Parameters

other

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

Return value

true if this date-time is equal to other both in their instant value, time zone, and their calendar, false otherwise.

Note that the time zones are canonicalized before comparison, so if their time zone IDs are both named and identify the same time zone, then they would be considered the same even when the exact names may be aliases of each other. Offset identifiers are compared by the offset values they represent. Offset identifiers never compare equal to named identifiers even when the named identifier's time zone always uses that offset.

Examples

Using equals()

// Asia/Kolkata and Asia/Calcutta are aliases of each other
const dt1 = Temporal.ZonedDateTime.from(
  "2021-07-01T12:34:56+05:30[Asia/Kolkata]",
);
const dt2 = Temporal.ZonedDateTime.from(
  "2021-07-01T12:34:56+05:30[Asia/Calcutta]",
);
console.log(dt1.equals(dt2)); // true

const dt3 = Temporal.ZonedDateTime.from("2021-07-01T12:34:56+05:30[+05:30]");
console.log(dt1.equals(dt3)); // false

const dt4 = Temporal.ZonedDateTime.from(
  "2021-07-01T12:34:56+05:30[Asia/Kolkata][u-ca=buddhist]",
);
console.log(dt1.equals(dt4)); // false

Testing if two time zone identifiers are equivalent

function sameTimeZone(timeZone1, timeZone2) {
  const dt1 = Temporal.ZonedDateTime.from({
    year: 2021,
    month: 7,
    day: 1,
    timeZone: timeZone1,
  });
  const dt2 = Temporal.ZonedDateTime.from({
    year: 2021,
    month: 7,
    day: 1,
    timeZone: timeZone2,
  });
  return dt1.equals(dt2);
}

console.log(sameTimeZone("Asia/Kolkata", "Asia/Calcutta")); // true
console.log(sameTimeZone("Asia/Shanghai", "Asia/Taipei")); // false

Specifications

Browser compatibility

See also

• Temporal.ZonedDateTime
• Temporal.ZonedDateTime.compare()