This feature is not Baseline because it does not work in some of the most widely-used browsers.
The round() method of Temporal.PlainDateTime instances returns a new Temporal.PlainDateTime object representing this date-time rounded to the given unit.
round(smallestUnit)
round(options)
smallestUnitA string representing the smallestUnit option. This is a convenience overload, so round(smallestUnit) is equivalent to round({ smallestUnit }), where smallestUnit is a string.
optionsAn object containing some or all of the following properties (in the order they are retrieved and validated):
roundingIncrement OptionalA 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 OptionalA string specifying how to round off the fractional part of smallestUnit. See Intl.NumberFormat(). Defaults to "halfExpand".
smallestUnitA 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.
A new Temporal.PlainDateTime object representing this date-time rounded to the given unit, where all units smaller than smallestUnit are zeroed out.
RangeErrorThrown if any of the options is invalid.
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
| Specification |
|---|
| Temporal # sec-temporal.plaindatetime.prototype.round |