The epochMilliseconds accessor property of Temporal.Instant instances returns an integer representing the number of milliseconds elapsed since the Unix epoch (midnight at the beginning of January 1, 1970, UTC) to this instant. It is equivalent to dividing epochNanoseconds by 1e6 and flooring the result.

The set accessor of epochMilliseconds is undefined. You cannot change this property directly. To create a new Temporal.Instant object with the desired new epochMilliseconds value, use the Temporal.Instant.fromEpochMilliseconds() static method instead.

Examples

Using epochMilliseconds

const instant = Temporal.Instant.from("2021-08-01T12:34:56.789Z");
console.log(instant.epochMilliseconds); // 1627821296789

const instant2 = Temporal.Instant.from("1969-08-01T12:34:56.789Z");
console.log(instant2.epochMilliseconds); // -13173903211

Changing epochMilliseconds

This is the method that allows you to move by any amount of time:

const instant = Temporal.Instant.from("2021-08-01T12:34:56.789Z");
const instant1hourLater = instant.add({ hours: 1 });
console.log(instant1hourLater.epochMilliseconds); // 1627824896789

If you already know the change in milliseconds, you can also directly construct a new Temporal.Instant object:

const instant = Temporal.Instant.from("2021-08-01T12:34:56.789Z");
const instant1hourLater = Temporal.Instant.fromEpochMilliseconds(
  instant.epochMilliseconds + 3600000,
);
console.log(instant1hourLater.epochMilliseconds); // 1627824896789

Specifications

Browser compatibility

See also

• Temporal.Instant
• Temporal.Instant.prototype.epochNanoseconds
• Temporal.Instant.fromEpochMilliseconds()