@burglekitt/gmt/dist/zoned/compare/isZonedRelativeDay.js

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

import { Temporal } from "@js-temporal/polyfill";
import { isValidZonedDateTime } from "../validate/index.js";
/**
 * Return true when `value`'s local calendar day falls `offsetDays` days from
 * today in `value`'s own IANA timeZone.
 *
 * - Subsumes `isZonedToday`/`isZonedYesterday`/`isZonedTomorrow`:
 *   `offsetDays: 0` is "today", `-1` is "yesterday", `1` is "tomorrow", and
 *   any other integer offset works the same way.
 * - "Today" is resolved in `value`'s own timeZone — no separate timeZone
 *   argument needed, since `value` already carries its IANA timeZone. This
 *   is the deterministic counterpart to `isRelativeDay`, which depends on
 *   the system clock and system timeZone: the same instant is "today" in
 *   `Pacific/Apia` and "yesterday" in `Pacific/Niue`, a 24-hour spread.
 * - `offsetDays` must be an integer; non-integer or non-finite values return false.
 * - Returns false if `value` is invalid.
 *
 * @param value ISO ZonedDateTime string
 * @param offsetDays integer number of days from today in `value`'s own timeZone
 * @returns true if `value`'s local day is exactly `offsetDays` days from today in its own timeZone, false on invalid input
 *
 * @example isZonedRelativeDay("2024-03-15T10:00:00-04:00[America/New_York]", 0) // true, if today is 2024-03-15 in America/New_York
 * @example isZonedRelativeDay("2024-03-14T10:00:00-04:00[America/New_York]", -1) // true, if today is 2024-03-15 in America/New_York
 * @example isZonedRelativeDay("2024-03-15T10:00:00+13:00[Pacific/Apia]", 0) // true, when the same instant is "yesterday" in Pacific/Niue
 * @example isZonedRelativeDay("invalid", 0) // false
 */
export function isZonedRelativeDay(value, offsetDays) {
    if (!isValidZonedDateTime(value) || !Number.isInteger(offsetDays)) {
        return false;
    }
    try {
        const zonedDateTime = Temporal.ZonedDateTime.from(value);
        const today = Temporal.Now.zonedDateTimeISO(zonedDateTime.timeZoneId).toPlainDate();
        const target = today.add({ days: offsetDays });
        return (Temporal.PlainDate.compare(zonedDateTime.toPlainDate(), target) === 0);
    }
    catch {
        return false;
    }
}