@burglekitt/gmt/dist/unix/interval/intervalAbutsUnix.js

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

/**
 * Return true when two Unix intervals are exactly adjacent — one's end equals the other's
 * start minus 1 (no gap, no overlap).
 *
 * - Compares numeric Unix epoch values directly.
 * - Returns `true` when `aEnd + 1 === bStart` or `bEnd + 1 === aStart`.
 * - Returns `false` when intervals overlap, are disjoint with a gap, or are invalid.
 * - Returns `false` on invalid input (non-numeric types, non-finite values).
 *
 * @param aStart Unix epoch value (seconds or milliseconds) — first interval start
 * @param aEnd Unix epoch value (seconds or milliseconds) — first interval end
 * @param bStart Unix epoch value (seconds or milliseconds) — second interval start
 * @param bEnd Unix epoch value (seconds or milliseconds) — second interval end
 * @returns true if intervals are exactly adjacent, or false on invalid input
 *
 * @example intervalAbutsUnix(0, 1500000000, 1500000001, 1700000000) // true
 * @example intervalAbutsUnix(1500000001, 1700000000, 0, 1500000000) // true
 * @example intervalAbutsUnix(0, 1500000000, 1500000002, 1700000000) // false (gap)
 * @example intervalAbutsUnix(0, 1500000001, 1500000000, 1700000000) // false (overlap)
 * @example intervalAbutsUnix(NaN, 1500000000, 1500000001, 1700000000) // false
 */
export function intervalAbutsUnix(aStart, aEnd, bStart, bEnd) {
    if ((typeof aStart !== "number" && typeof aStart !== "string") ||
        (typeof aEnd !== "number" && typeof aEnd !== "string") ||
        (typeof bStart !== "number" && typeof bStart !== "string") ||
        (typeof bEnd !== "number" && typeof bEnd !== "string")) {
        return false;
    }
    const n1 = typeof aStart === "number" ? aStart : Number(aStart);
    const n2 = typeof aEnd === "number" ? aEnd : Number(aEnd);
    const n3 = typeof bStart === "number" ? bStart : Number(bStart);
    const n4 = typeof bEnd === "number" ? bEnd : Number(bEnd);
    if (!Number.isFinite(n1) ||
        !Number.isFinite(n2) ||
        !Number.isFinite(n3) ||
        !Number.isFinite(n4)) {
        return false;
    }
    if (n1 > n2) {
        return false;
    }
    if (n3 > n4) {
        return false;
    }
    // aEnd + 1 === bStart
    if (n2 + 1 === n3) {
        return true;
    }
    // bEnd + 1 === aStart
    if (n4 + 1 === n1) {
        return true;
    }
    return false;
}