The subtract() method of Temporal.Instant instances returns a new Temporal.Instant object representing this instant moved backward by a given duration (in a form convertible by Temporal.Duration.from()).
If you want to subtract two instants and get a duration, use since() or until() instead.
subtract(duration)durationA string, an object, or a Temporal.Duration instance representing a duration to subtract from this instant. It is converted to a Temporal.Duration object using the same algorithm as Temporal.Duration.from().
A new Temporal.Instant object representing subtracting duration from this instant. If duration is positive, then the returned instant is earlier than this instant; if duration is negative, then the returned instant is later than this instant.
RangeErrorThrown in one of the following cases:
duration is a calendar duration (it has a non-zero years, months, or weeks), or has a non-zero days, because calendar durations are ambiguous without a calendar and time reference.Subtracting a duration is equivalent to adding its negation, so all the same considerations apply.
const instant = Temporal.Instant.fromEpochMilliseconds(1000);
const duration = Temporal.Duration.from("PT1S"); // One-second duration
const newInstant = instant.subtract(duration);
console.log(newInstant.epochMilliseconds); // 0For more examples, see add().