Getting the User’s Last Name in Windows 10 Apps using JavaScript

function getUserlastNameAC() {
    if (Windows.System.UserProfile.UserInformation.nameAccessAllowed) {
        Windows.System.UserProfile.UserInformation.getLastNameAsync().done(function (data) {
            if (data) {
               return data;
            } 
        });
    } else {
        return "Last Name cannot be accessed because this functionality is disabled by Privacy Setting or Group Policy in Windows 10";
    }
}