isISODate
Checks if a string is a valid ISO 8601 date string.
1/**
2 * Checks if a string is a valid ISO 8601 date string.
3 *
4 * Accepts formats like:
5 * - "2023-06-30"
6 * - "2023-06-30T15:20:30Z"
7 * - "2023-06-30T15:20:30+02:00"
8 *
9 * @param str - The date string to validate.
10 * @returns True if the string is a valid ISO date.
11 */
12export function isISODate(str: string): boolean {
13 const isoRegex = /^\d{4}-\d{2}-\d{2}(T\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[\+\-]\d{2}:\d{2})?)?$/;
14 return isoRegex.test(str) && !isNaN(Date.parse(str));
15}Strict ISO 8601 Compliance
The regex explicitly enforces ISO 8601 formats, supporting both date-only and full datetime variants with optional timezone info.
Dual-Layer Validation
Combines regex format checking with
Date.parseto ensure both syntactic and semantic correctness.Supports Timezone Offsets and UTC
Accepts both
Z(UTC) and±HH:MMoffsets, covering the full range of ISO-compatible datetime strings.Efficient and Lightweight
Validation is done with minimal computation, making it suitable for large-scale input checks.
Tests | Examples
1test('isISODate - accepts ISO date only', () => {
2 expect(isISODate('2023-06-30')).toBe(true);
3});
4
5test('isISODate - accepts full ISO datetime with Z', () => {
6 expect(isISODate('2023-06-30T15:20:30Z')).toBe(true);
7});
8
9test('isISODate - accepts ISO datetime with timezone offset', () => {
10 expect(isISODate('2023-06-30T15:20:30+02:00')).toBe(true);
11});
12
13test('isISODate - rejects malformed date', () => {
14 expect(isISODate('2023/06/30')).toBe(false);
15});
16
17test('isISODate - rejects invalid date', () => {
18 expect(isISODate('2023-02-30')).toBe(false);
19});
20
21test('isISODate - rejects random text', () => {
22 expect(isISODate('not-a-date')).toBe(false);
23});Common Use Cases
API Payload Validation
Ensure incoming date strings from JSON APIs conform to ISO standards before parsing or storing.
Form Input Validation
Validate date/time fields in user-facing forms (e.g., booking systems, schedulers).
Data Import/Export
Sanitize or validate date strings when transferring data between systems or formats.
Database Timestamp Checks
Confirm that dates stored or retrieved from a database follow the expected ISO format.