upper case both last name when there is a dash in between

I would like to modify an existing JavaScript function that formats a user name properly by setting the first name first letter to upper case, as well as the first name of the last name.

There are some last names that are hyphenated and when those happen, they look like Hugo Bearsotti-potz, when in fact it should be Hugo Bearsotti-Potz

I would like to ask for help to modify this function so it allows proper case to hyphenated last names, if possible.

Here is the existing code (pertinent snippet only):

        if (input) {
            var out = '';
            input.split(delimiter || ' ').forEach(function (sector) {
                var x = sector.toLowerCase();
                out += x.charAt(0).toUpperCase() + x.substr(1) + ' ';
            });
            if (out.length > 0) {
                out = out.substring(0, out.length - 1);
            }
            return out;
        }

Many thanks.