While this is probably beating a dead horse at this point, I have a
basic implementation of this in JavaScript, covering ISBN-10 and
ISBN-13, as well as EAN (UPC) and ISSN:
https://github.com/ajlyon/identifiers-js

In case someone is interested. One issue is that apparently, if
Wikipedia is to be believed, there are books out there issued with
ISBNs that aren't valid, so any strong enforcement using the check
digit may lead to the occasional issue.

Avram
UCLA Slavic

On Fri, Oct 21, 2011 at 10:44 AM, Kozlowski,Brendon <[log in to unmask]> wrote:
[..]
> However, I now find that I need to validate both the 10-digit and 13-digit ISBNs. I realize there's also a check digit and a REGEX cannot check this value - one step at a time. Right now I just want to work on the REGEX.
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> Does anyone know the exact specifications of both forms of an ISBN? The ISBN organization's website didn't seem to be overly clear to me. Alternatively, if anyone has a full working regular expression for this purpose I would definitely not mind if they'd be willing to share.