@burglekitt/gmt
Version:
Temporal-based date and time utilities with timezone support and polyfill integration
52 lines (51 loc) • 2.18 kB
JavaScript
/**
* Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
*
* - Compares numeric Unix epoch values directly.
* - Adjacent intervals (e.g. `aEnd === bStart`) do NOT overlap — returns `false`.
* - Returns `false` if either interval is invalid (`start > end`).
* - 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 overlap, or false on invalid input
*
* @example intervalsOverlapUnix(0, 1700000000, 1000000, 2000000) // true
* @example intervalsOverlapUnix(0, 1000000, 1000000, 2000000) // false (adjacent)
* @example intervalsOverlapUnix(0, 1000000, 1000001, 2000000) // false (disjoint)
* @example intervalsOverlapUnix(NaN, 1700000000, 1000000, 2000000) // false
* @example intervalsOverlapUnix("0", "1700000000", "1000000", "2000000") // true
*/
export function intervalsOverlapUnix(aStart, aEnd, bStart, bEnd) {
if (typeof aStart !== "number" && typeof aStart !== "string") {
return false;
}
if (typeof aEnd !== "number" && typeof aEnd !== "string") {
return false;
}
if (typeof bStart !== "number" && typeof bStart !== "string") {
return false;
}
if (typeof bEnd !== "number" && typeof bEnd !== "string") {
return false;
}
const a1 = typeof aStart === "number" ? aStart : Number(aStart);
const a2 = typeof aEnd === "number" ? aEnd : Number(aEnd);
const b1 = typeof bStart === "number" ? bStart : Number(bStart);
const b2 = typeof bEnd === "number" ? bEnd : Number(bEnd);
if (!Number.isFinite(a1) ||
!Number.isFinite(a2) ||
!Number.isFinite(b1) ||
!Number.isFinite(b2)) {
return false;
}
if (a1 > a2) {
return false;
}
if (b1 > b2) {
return false;
}
return a2 >= b1 && b2 >= a1;
}