localhost / userdir on macOS High Sierra
Like on Sierra vhosts seem to need to be activated

so:


  sudo vi /etc/apache2/httpd.conf


and uncomment the following lines by removing the hashtag (#)


  .#LoadModule vhost_alias_module libexec/apache2/mod_vhost_alias.so 


and


  .#Include /private/etc/apache2/extra/httpd-vhosts.conf


then


  sudo apachectl restart


and you'll be good to go