Site.processHref (href)
href URL postprocessor. If a virtual host mapping is defined for this site's alias, use it. Otherwise, use normal site URL.

Sourcecode in Site/objectFunctions.js:
1:   function processHref(href) {
2:      var vhost = app.properties["vhost." + this.alias];
3:      if (vhost)
4:         return vhost + href;
5:      else
6:         return app.properties.defaulthost + "/" + this.alias + href;
7:   }