Regular expression - also empty string allowed

Question

I have the following regular expression... This one does not allow empty String. How do I have to manipulate?

var phoneReg = new RegExp(/^\+?[0-9]+(\([0-9]+\))?[0-9-]*[0-9]$/i);

Answer 1

Just use the "zero or one" operator ?, such as:

/^(?:regex)?$/
           ^

(?:regex) simply makes the concerned ground uncapturable (i.e. no need to change your $X, \X or ?X indexes if any).