The since() method of Temporal.PlainDateTime instances returns a new Temporal.Duration object representing the duration from another date-time (in a form convertible by Temporal.PlainDateTime.from()) to this date-time. The duration is positive if the other date-time is before this date-time, 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, an object, or a Temporal.PlainDateTime instance representing a date-time to subtract from this date-time. It is converted to a Temporal.PlainDateTime object using the same algorithm as Temporal.PlainDateTime.from(). It must have the same calendar as this.

options Optional

An object containing the options for Temporal.Duration.prototype.round(), which includes largestUnit, roundingIncrement, roundingMode, and smallestUnit. largestUnit and smallestUnit accept all possible units. For largestUnit, the default value "auto" means "days" or smallestUnit, whichever is greater. For smallestUnit, the default value is "nanoseconds". The current date is used as the relativeTo option. Note that using units larger than "days" may make the duration not portable to other calendars or dates.

Return value

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

Exceptions

RangeError

Thrown in one of the following cases:

• other has a different calendar than this.
• Any of the options is invalid.

Examples

Using since()

let lastBilling = Temporal.PlainDateTime.from({
  year: Temporal.Now.plainDateISO().year,
  month: 4,
  day: 1,
});
const now = Temporal.Now.plainDateTimeISO().round("second");
if (Temporal.PlainDateTime.compare(lastBilling, now) > 0) {
  lastBilling = lastBilling.subtract({ years: 1 });
}
const duration = now.since(lastBilling);
console.log(`${duration.toLocaleString("en-US")} since last billing`);
// Expected output: "[number] days, [number] hr, [number] min, [number] sec since last billing"

const duration2 = now.since(lastBilling, { smallestUnit: "days" });
console.log(`${duration2.toLocaleString("en-US")} since last billing`);
// Expected output: "[number] days since last billing"

const duration3 = now.since(lastBilling, {
  largestUnit: "years",
  smallestUnit: "days",
});
console.log(`${duration3.toLocaleString("en-US")} since last billing`);
// Expected output: "[number] months, [number] days since last billing"

Rounding the result

By default the fractional part of the smallestUnit is truncated. You can round it up using the roundingIncrement and roundingMode options.

const dt1 = Temporal.PlainDateTime.from("2022-01-01T00:00:00");
const dt2 = Temporal.PlainDateTime.from("2022-01-28T12:34:56");
const duration = dt2.since(dt1, {
  smallestUnit: "days",
  roundingIncrement: 5,
  roundingMode: "ceil",
});
console.log(duration.toString()); // "P30D"

Specifications

Browser compatibility

See also

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