@burglekitt/gmt/dist/plain/interval/validate/isValidDateInterval.js

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

import { Temporal } from "@js-temporal/polyfill";
import { parseCalendarDateValue } from "../../../internal/index.js";
import { isValidCalendarDate } from "../../validate/index.js";
/**
 * Return true if `start` and `end` form a valid date interval — both parseable as
 * ISO PlainDate strings and `start <= end`.
 *
 * - Both inputs must be ISO 8601 date strings (e.g. `"2024-01-01"`).
 * - Equal `start === end` is valid.
 * - Invalid input, malformed strings, or leap-second strings return `false`.
 * - Accepts GMT calendar-annotated PlainDate strings — E5 (issue #78). Ordering is
 *   calendar-independent, so `start`/`end` may carry different or no calendar tags (D4).
 *
 * @param start ISO 8601 date string (interval start), optionally calendar-annotated
 * @param end ISO 8601 date string (interval end), optionally calendar-annotated
 * @returns true if start and end form a valid date interval, or false on invalid input
 *
 * @example isValidDateInterval("2024-01-01", "2024-12-31") // true
 * @example isValidDateInterval("2024-01-01", "2024-01-01") // true
 * @example isValidDateInterval("2024-12-31", "2024-01-01") // false
 * @example isValidDateInterval("invalid", "2024-12-31") // false
 * @example isValidDateInterval("5785-01-01[u-ca=hebrew]", "2024-12-31") // true (mixed calendars — ordering is calendar-independent)
 */
export function isValidDateInterval(start, end) {
    if (typeof start !== "string" || typeof end !== "string") {
        return false;
    }
    if (!isValidCalendarDate(start) || !isValidCalendarDate(end)) {
        return false;
    }
    try {
        return (Temporal.PlainDate.compare(parseCalendarDateValue(start), parseCalendarDateValue(end)) <= 0);
    }
    catch {
        return false;
    }
}