vremel/src/datetime/endOfSecond.ts

JavaScript date utility library for Temporal API

import type { Temporal } from "../types.js";

/**
 * Returns the end of a second for the given datetime
 * @param dt datetime object which includes time info
 * @returns Temporal object which represents the end of the second
 */
export function endOfSecond<
	DateTime extends
		| Temporal.PlainTime
		| Temporal.PlainDateTime
		| Temporal.ZonedDateTime,
>(dt: DateTime): DateTime {
	// assumption: no sub-second offset transition in timezone database
	return dt.with({
		millisecond: 999,
		microsecond: 999,
		nanosecond: 999,
	}) as DateTime;
}