TypeError: pattern.test is not a function

Your pattern must be RegEx literal (double quotes around that should not be there) like this

var pattern = /^(()?\d{3}())?(-|\s)?\d{3}(-|\s)?\d{4}$/;

Otherwise you need to use RegExp object, with proper escaping for \, like this

var pattern = new RegExp("^(()?\\d{3}())?(-|\\s)?\\d{3}(-|\\s)?\\d{4}$");