Temporal.PlainDateTime.prototype.round()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The round() method of Temporal.PlainDateTime instances returns a new Temporal.PlainDateTime object representing this date-time rounded to the given unit.

Syntax

round(smallestUnit)
round(options)

Parameters

smallestUnit

A string representing the smallestUnit option. This is a convenience overload, so round(smallestUnit) is equivalent to round({ smallestUnit }), where smallestUnit is a string.

options

An object containing some or all of the following properties (in the order they are retrieved and validated):

roundingIncrement Optional: A number (truncated to an integer) representing the rounding increment in the given smallestUnit. Defaults to 1. For all values of smallestUnit except "day", the increment must be a divisor of the maximum value of the unit; for example, if the unit is hours, the increment must be a divisor of 24 and must not be 24 itself, which means it can be 1, 2, 3, 4, 6, 8, or 12. For "day", the increment must be 1.
roundingMode Optional: A string specifying how to round off the fractional part of smallestUnit. See Intl.NumberFormat(). Defaults to "halfExpand".
smallestUnit: A string representing the smallest unit to include in the output. The value must be one of the following: "day", "hour", "minute", "second", "millisecond", "microsecond", "nanosecond", or their plural forms. For units larger than "nanosecond", fractional parts of the smallestUnit will be rounded according to the roundingIncrement and roundingMode settings.

Return value

A new Temporal.PlainDateTime object representing this date-time rounded to the given unit, where all units smaller than smallestUnit are zeroed out.

Exceptions

RangeError: Thrown if any of the options is invalid.

Examples

Rounding off small units

const dt = Temporal.PlainDateTime.from("2021-07-01T12:34:56.123456789");
const nearestMillisecond = dt.round("millisecond");
console.log(nearestMillisecond.toString()); // 2021-07-01T12:34:56.123

const nearestHalfHour = dt.round({
  smallestUnit: "minute",
  roundingIncrement: 30,
});
console.log(nearestHalfHour.toString()); // 2021-07-01T12:30:00

const nextDay = dt.round({ smallestUnit: "day", roundingMode: "ceil" });
console.log(nextDay.toString()); // 2021-07-02T00:00:00

Specifications

Specification
Temporal proposal # sec-temporal.plaindatetime.prototype.round

Browser compatibility

	Desktop					Mobile						Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	Deno	Node.js
`round`	No	No	No	No	No	No	No	No	No	No	No	1.40	No