isUUIDv4

1/**
2 * Checks if a string is a valid UUID v4.
3 *
4 * @param value - The string to validate.
5 * @returns True if the string is a valid UUID v4, false otherwise.
6 */
7export function isUUIDv4(value: string): boolean {
8  const uuidV4Regex = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
9  return uuidV4Regex.test(value);
10}

• Strict UUID v4 Format Enforcement

  The regular expression explicitly checks for version 4 UUIDs (with a "4" in the third block and "[89ab]" in the fourth), ensuring precise validation.

• Case-Insensitive Matching

  Supports uppercase and lowercase hexadecimal characters via the i flag for flexibility in input.

• Lightweight and Dependency-Free

  Does not rely on external libraries like uuid or validator, making it portable and fast.

• Reliable Input Filtering

  Prevents malformed UUIDs from slipping through, which is crucial for database keys, API parameters, and security contexts.

Tests | Examples

1test('returns true for valid UUID v4', () => {
2  expect(isUUIDv4('550e8400-e29b-41d4-a716-446655440000')).toBe(true);
3  expect(isUUIDv4('f47ac10b-58cc-4372-a567-0e02b2c3d479')).toBe(true);
4});
5
6test('returns false for invalid UUID format', () => {
7  expect(isUUIDv4('550e8400-e29b-11d4-a716-446655440000')).toBe(false); // wrong version
8  expect(isUUIDv4('550e8400e29b41d4a716446655440000')).toBe(false); // no dashes
9  expect(isUUIDv4('')).toBe(false);
10});
11
12test('returns false for non-string inputs', () => {
13  expect(isUUIDv4(null as any)).toBe(false);
14  expect(isUUIDv4(undefined as any)).toBe(false);
15  expect(isUUIDv4(123 as any)).toBe(false);
16});

Common Use Cases

• Validating API Request Parameters

  Confirm that route or query parameters expected to be UUIDs are properly formatted.

• Form Input Validation

  Check if user-provided identifiers are valid UUID v4 values before submission.

• Database Record Lookup

  Ensure that IDs used for querying records follow the UUID v4 standard.

• Filtering or Cleaning Incoming Data

  Discard or flag invalid UUIDs in datasets or event payloads.

• Generating Type Guards for TypeScript

  Use it to narrow types in conditional checks when working with dynamic values.