Temporal.ZonedDateTime.prototype.epochMilliseconds

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 epochMilliseconds accessor property of Temporal.ZonedDateTime 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.ZonedDateTime object with the desired new epochMilliseconds value, see below.

Examples

Using epochMilliseconds

js
const zdt = Temporal.ZonedDateTime.from("2021-08-01T12:34:56.789Z[UTC]");
console.log(zdt.epochMilliseconds); // 1627821296789

const zdt2 = Temporal.ZonedDateTime.from("1969-08-01T12:34:56.789Z[UTC]");
console.log(zdt2.epochMilliseconds); // -13173903211

Creating a ZonedDateTime object from an epochMilliseconds value

You can create a Temporal.ZonedDateTime object from an epochMilliseconds value by first constructing a Temporal.Instant object using Temporal.Instant.fromEpochMilliseconds(), and then converting it to a Temporal.ZonedDateTime object using Temporal.Instant.prototype.toZonedDateTimeISO():

js
const epochMilliseconds = 1627821296789;
const instant = Temporal.Instant.fromEpochMilliseconds(epochMilliseconds);
const zdt = instant.toZonedDateTimeISO("UTC");
console.log(zdt.toString()); // 2021-08-01T12:34:56.789+00:00[UTC]

Alternatively, use the Temporal.ZonedDateTime() constructor, but convert the milliseconds to nanoseconds first:

js
const epochMilliseconds = 1627821296789;
const epochNanoseconds = BigInt(epochMilliseconds) * 1e6n;
const zdt = new Temporal.ZonedDateTime(epochNanoseconds, "UTC");
console.log(zdt.toString()); // 2021-08-01T12:34:56.789+00:00[UTC]

Specifications

Specification
Temporal proposal
# sec-get-temporal.zoneddatetime.prototype.epochmilliseconds

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
epochMilliseconds
Experimental

Legend

Tip: you can click/tap on a cell for more information.

No support
No support
Experimental. Expect behavior to change in the future.
See implementation notes.
User must explicitly enable this feature.

See also