The subtract() method of Temporal.PlainTime instances returns a new Temporal.PlainTime object representing this time moved backward by a given duration (in a form convertible by Temporal.Duration.from()), wrapping around the clock if necessary.
If you want to subtract two times 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 time. It is converted to a Temporal.Duration object using the same algorithm as Temporal.Duration.from().
A new Temporal.PlainTime object representing the time specified by the original PlainTime, minus the duration.
Subtracting a duration is equivalent to adding its negation, so all the same considerations apply.
const start = Temporal.PlainTime.from("12:34:56");
const end = start.subtract({ hours: 1, minutes: 30 });
console.log(end.toString()); // 11:04:56For more examples, see add().