Including a hyphen in a regex character bracket?

Question

$.validator.addMethod('AZ09_', function (value) { 
    return /^[a-zA-Z0-9.-_]+$/.test(value); 
}, 'Only letters, numbers, and _-. are allowed');

When I use somehting like test-123 it still triggers as if the hyphen is invalid. I tried \- and --

Answer 1

Escaping the hyphen using \- is the correct way.

I have verified that the expression /^[a-zA-Z0-9.\-_]+$/ does allow hyphens. You can also use the \w class to shorten it to /^[\w.\-]+$/.

(Putting the hyphen last in the expression actually causes it to not require escaping, as it then can't be part of a range, however you might still want to get into the habit of always escaping it.)

Answer 2

Escaping using \- should be fine, but you can also try putting it at the beginning or the end of the character class. This should work for you:

/^[a-zA-Z0-9._-]+$/

Answer 3

\- should work to escape the - in the character range. Can you quote what you tested when it didn't seem to? Because it seems to work: http://jsbin.com/odita3

Answer 4

The \- maybe wasn't working because you passed the whole stuff from the server with a string. If that's the case, you should at first escape the \ so the server side program can handle it too.

• In a server side string: \\-
• On the client side: \-
• In regex (covers): -

Or you can simply put at the and of the [] brackets.