isAlphanumeric

1/**
2 * Checks if a string contains only letters and numbers (A–Z, a–z, 0–9).
3 *
4 * @param str - The string to validate.
5 * @returns True if the string is alphanumeric, false otherwise.
6 */
7export function isAlphanumeric(str: string): boolean {
8  return /^[A-Za-z0-9]+$/.test(str);
9}

• Fast and Lightweight

  Performs validation with a single regular expression — no external dependencies or heavy parsing logic.

• Strict Format Enforcement

  Ensures the string consists only of letters and numbers, rejecting any punctuation, spaces, or symbols.

• Consistent Behavior Across Browsers

  Uses standard JavaScript regex, guaranteeing predictable results in all environments.

• Reusable Utility

  Easy to integrate into both client-side and server-side validation pipelines.

Tests | Examples

1test('isAlphanumeric - valid alphanumeric strings', () => {
2  expect(isAlphanumeric('abc123')).toBe(true);
3  expect(isAlphanumeric('ABC')).toBe(true);
4  expect(isAlphanumeric('123456')).toBe(true);
5});
6
7test('isAlphanumeric - invalid strings with symbols or spaces', () => {
8  expect(isAlphanumeric('abc123!')).toBe(false);
9  expect(isAlphanumeric('hello world')).toBe(false);
10  expect(isAlphanumeric('')).toBe(false);
11});

Common Use Cases

• Username Validation

  Enforce simple, secure, and readable usernames without special characters.

• Coupon or Promo Code Checks

  Validate alphanumeric-only codes submitted by users or generated programmatically.

• Form Field Sanitization

  Ensure certain fields (e.g. IDs, labels, product SKUs) do not contain invalid characters.

• Password Policy Checks (Basic)

  Enforce that a password includes only letters and digits for legacy systems or simple policies.