Temporal.PlainDate.prototype.since()
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
The since() method of Temporal.PlainDate instances returns a new Temporal.Duration object representing the duration from another date (in a form convertible by Temporal.PlainDate.from()) to this date. The duration is positive if the other date is before this date, 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.PlainDateinstance representing a date to subtract from this date. It is converted to aTemporal.PlainDateobject using the same algorithm asTemporal.PlainDate.from(). It must have the same calendar asthis. optionsOptional-
An object containing the options for
Temporal.Duration.prototype.round(), which includeslargestUnit,roundingIncrement,roundingMode, andsmallestUnit.largestUnitandsmallestUnitonly accept the units:"years","months","weeks","days", or their singular forms. ForlargestUnit, the default value"auto"means"days"orsmallestUnit, whichever is greater. ForsmallestUnit, the default value is"days". The current date is used as therelativeTooption. 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. The duration is positive if other is before this date, and negative if after.
Exceptions
RangeError-
Thrown in one of the following cases:
otherhas a different calendar thanthis.- Any of the options is invalid.
Examples
Using since()
const date = Temporal.PlainDate.from("2022-12-25");
const now = Temporal.Now.plainDateISO();
const duration = now.since(date);
const formatter = new Intl.DurationFormat("en-US", { style: "long" });
console.log(`It's been ${formatter.format(duration)} since that Christmas...`);
// Expected output: "It's been [number] days since that Christmas..."
const duration2 = now.since(date, { smallestUnit: "months" });
console.log(`It's been ${formatter.format(duration2)} since that Christmas...`);
// Expected output: "It's been [number] months since that Christmas..."
const duration3 = now.since(date, {
largestUnit: "years",
smallestUnit: "months",
});
console.log(`It's been ${formatter.format(duration3)} since that Christmas...`);
// Expected output: "It's been [number] years, [number] months since that Christmas..."
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 date1 = Temporal.PlainDate.from("2022-01-01");
const date2 = Temporal.PlainDate.from("2022-01-28");
const duration = date2.since(date1, {
smallestUnit: "days",
roundingIncrement: 5,
roundingMode: "ceil",
});
console.log(duration.toString()); // "P30D"
Comparing different calendars
By default, the two dates must have the same calendar. This is to avoid ambiguity in the meaning of months and years. If you want to compare dates from different calendars, you can convert them to the same calendar first.
const date1 = Temporal.PlainDate.from("2022-01-01");
const date2 = Temporal.PlainDate.from("2022-01-28[u-ca=chinese]");
const duration = date2.withCalendar("iso8601").since(date1);
console.log(duration.toString()); // "P27D"
Specifications
| Specification |
|---|
| Temporal # sec-temporal.plaindate.prototype.since |
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Legend
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- See implementation notes.