regex - Exclusive Or in Regular Expression

Question

Looking for a bit of regex help. I'd like to design an expression that matches a string with "foo" OR "bar", but not both "foo" AND "bar"

If I do something like...

/((foo)|(bar))/

It'll match "foobar". Not what I'm looking for. So, how can I make regex match only when one term or the other is present?

Thanks!

Answer 1

This is what I use:

/^(foo|bar){1}$/

See: http://www.regular-expressions.info/quickstart.html under repetition