Simultaneous Client and Server Form Validation using Custom Tag Library

Question

I am developing a custom tag library for validator tags
which are capable of doing client side validation (Javascript)
and server side (Java). My problem is with the development
of a regular expression based validator. Because of differences
in the way Javascript and Java handle regular expressions
i can not use the same regular expression for both types of
validation. Is there any way to convert a valid regular
expression from the java.util.regex format into the Javascript
format or vice versa? My major problems are with the (or, ||)
statements and the user of backslashes.

Answer 1

If you are speaking of RE syntax flavours, they are basically the same(namely perl5 flavour). Any expression that works in JS should work in j.u.regex too.
Though, their usage is quite different.
So, there is no need for convertion of expressions.
But porting the code may be not so trivial.