Temporal.ZonedDateTime.prototype.offsetNanoseconds

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The offsetNanoseconds accessor property of Temporal.ZonedDateTime instances returns an integer representing the offset used to interpret the internal instant, as a number of nanoseconds (positive or negative). The value is a safe integer because it's less than a day, which is 8.64e15 nanoseconds.

The set accessor of offsetNanoseconds is undefined. You cannot change this property directly. Use the with() method to create a new Temporal.ZonedDateTime object with the desired new offset value (which will change this property too), or use the withTimeZone() method to create a new Temporal.ZonedDateTime object in another time zone.

Examples

Using offsetNanoseconds

const dt = Temporal.ZonedDateTime.from(
  "2021-07-01T12:00:00-07:00[America/Los_Angeles]",
);
console.log(dt.offsetNanoseconds); // -25200000000000

const dt2 = Temporal.ZonedDateTime.from(
  "2021-07-01T12:00:00+08:00[Asia/Shanghai]",
);
console.log(dt2.offsetNanoseconds); // 28800000000000

const dt3 = Temporal.ZonedDateTime.from(
  "1900-01-01T00:00:00+00:09:21[Europe/Paris]",
);
console.log(dt3.offsetNanoseconds); // 561000000000

Here's one way to get a ZonedDateTime representing the same wall-clock time in UTC:

const dt = Temporal.ZonedDateTime.from(
  "2021-07-01T12:00:00-07:00[America/Los_Angeles]",
);
const dtInUTC = dt.add({ nanoseconds: dt.offsetNanoseconds });
console.log(dtInUTC.withTimeZone("UTC").toString()); // "2021-07-01T12:00:00+00:00[UTC]"

Here's a better way to get the same result:

const dt = Temporal.ZonedDateTime.from(
  "2021-07-01T12:00:00-07:00[America/Los_Angeles]",
);
const dtInUTC = dt.toPlainDateTime().toZonedDateTime("UTC");
console.log(dtInUTC.toString()); // "2021-07-01T12:00:00+00:00[UTC]"