Test if links are external with jQuery / javascript?

Question

How do I test to see if links are external or internal? Please note:

1. I cannot hard code the local domain.
2. I cannot test for \"http\". I could just as

Answer 1

var external = RegExp('^((f|ht)tps?:)?//(?!' + location.host + ')');

Usage:

external.test('some url'); // => true or false