@burglekitt/gmt/dist/utc/calculate/startOfUtc.js

Temporal-based date and time utilities with timezone support and polyfill integration

import { Temporal } from "@js-temporal/polyfill";
import { startOrEndOfUtc } from "./startOrEndOfUtc.js";
/**
 * Return the start of the specified date-time `unit` for a given UTC datetime string.
 *
 * - Converts to ZonedDateTime, sets to start of unit, converts back to Instant.
 * - Supports: "year", "month", "week", "day", "hour", "minute", "second", "millisecond", "microsecond", "nanosecond".
 * - Returns "" for invalid input.
 *
 * @param value ISO UTC datetime string
 * @param unit Temporal.DateUnit | Temporal.TimeUnit to specify the start
 * @param options optional: weekStartsOn ("monday" | "sunday"), fractionalSecondDigits (number)
 * @returns UTC Instant string representing the start of the unit, or "" on invalid input
 *
 * @example startOfUtc("2024-03-15T14:30:45Z", "year") // "2024-01-01T00:00:00Z"
 * @example startOfUtc("2024-03-15T14:30:45Z", "month") // "2024-03-01T00:00:00Z"
 * @example startOfUtc("invalid", "year") // ""
 */
export function startOfUtc(value, unit, options) {
    return startOrEndOfUtc(value, unit, options ?? {}, false);
}