The since() method of Temporal.Instant instances returns a new Temporal.Duration object representing the duration from another instant (in a form convertible by Temporal.Instant.from()) to this instant. The duration is positive if the other instant is before this instant, and negative if after.

This method does this - other. To do other - this, use the until() method.

Syntax

since(other)
since(other, options)

Parameters

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: "hours", "minutes", "seconds", "milliseconds", "microseconds", "nanoseconds", or their singular forms. For largestUnit, the default value "auto" means "seconds" or smallestUnit, whichever is greater. For smallestUnit, the default value is "nanoseconds".

Return value

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.

Exceptions

RangeError

Thrown if any of the options is invalid.

Examples

Using since()

const lastUpdated = Temporal.Instant.fromEpochMilliseconds(1735235418000);
const now = Temporal.Now.instant();
const duration = now.since(lastUpdated, { smallestUnit: "minute" });
console.log(`Last updated ${duration.toLocaleString("en-US")} ago`);

Balancing the resulting duration

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: "minutes" });
const roundedDuration = duration.round({
  largestUnit: "years",
  // 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`);

Specifications

Browser compatibility

See also

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