isbn

Validates an ISBN (International Standard Book Number) — ISBN-10 or ISBN-13.

Options

Option	Type	Default	Description
message	string	locale default	Custom error message

Playground

Valid values

Value	Notes
"978-0-306-40615-2"	Valid ISBN-13 with hyphens
"0-306-40615-2"	Valid ISBN-10 with hyphens
"9780306406157"	Valid ISBN-13 without hyphens

Invalid values

Value	Reason
"978-0-306-40615-3"	Wrong check digit
"12345"	Too short

Notes

• Empty string ("") always returns valid: true. Combine with notEmpty to require a value.
• Accepts both ISBN-10 (10 digits) and ISBN-13 (978- or 979- prefix, 13 digits).
• Hyphens are optional and ignored during validation.