Temporal.Instant.prototype.since()

other

A string or a Temporal.Instant instance representing an instant to subtract from this instant. It is converted to a Temporal.Instant object using the same algorithm as Temporal.Instant.from().

options Optional

An object containing the options for Temporal.Duration.prototype.round(), which includes largestUnit, roundingIncrement, roundingMode, and smallestUnit. largestUnit and smallestUnit only accept the units: "hour", "minute", "second", "millisecond", "microsecond", "nanosecond", or their plural forms. For largestUnit, the default value "auto" means "second" or smallestUnit, whichever is greater. For smallestUnit, the default value is "nanosecond".

A new Temporal.Duration object representing the duration since other to this instant. The duration is positive if other is before this instant, and negative if after.

RangeError

Thrown if any of the options is invalid.

Because an instant does not carry calendar information, the resulting duration avoids calendar durations, which are ambiguous without a calendar and time reference. Therefore, the result is unbalanced because hours may be greater than 24. To balance the duration, round the resulting duration again with the desired largestUnit, passing a relativeTo that carries the calendar information.

const lastUpdated = Temporal.Instant.fromEpochMilliseconds(1735235418000);
const now = Temporal.Now.instant();
const duration = now.since(lastUpdated, { smallestUnit: "minute" });
const roundedDuration = duration.round({
  largestUnit: "year",
  // Use the ISO calendar; you can convert to another calendar using
  // withCalendar()
  relativeTo: now.toZonedDateTimeISO("UTC"),
});
console.log(`Last updated ${roundedDuration.toLocaleString("en-US")} ago`);

• Temporal.Instant
• Temporal.Duration
• Temporal.Instant.prototype.add()
• Temporal.Instant.prototype.subtract()
• Temporal.Instant.prototype.until()