Need to document that global regexes will lead to weird bugs

[danmactough]

The matches validator uses RegExp#test(), which means you CANNOT pass global regular expressions, or the validator will not work as expected.

Example:

var re = /^[a-zA-Z0-9_-]+$/gi; // note the "g" for global (not to mention the redundant "i")
var str = 'one';

re.test(str); // true
re.test(str); // false
re.test(str); // true
re.test(str); // false
re.test(str); // true
re.test(str); // false
re.test(str); // true
re.test(str); // false
re.test(str); // true
re.test(str); // false
re.test(str); // true
re.test(str); // false

[cpsubrian]

Had no idea it worked like this.

[danmactough]

Yeah. If you don't reuse the regex (which is our usual m.o.), it doesn't come up. But here, the whole point is to reuse the same regex object. Good times.