code: function URL(url, baseURL) {
              if ( url != undefined ) {
                  let _url = URL.parseUrl(url);
                  if ( _url !== false ) return _url;
                  if ( baseURL ) {
                      _url = URL.parseUrl(baseURL);
                      if ( _url === false ) return;
                      url = String(url);
                      if ( url.slice(0,2) == '//' ) {
                          return URL.parseUrl(_url.protocol + url);
                      }
                      let _path;
                      if ( url.slice(0,1) == '/' ) {
                          _path = url;
                      }
                      else {
                          _path = _url.pathname.split('/');
                          _path[_path.length-1] = url;
                          _path = _path.join('/');
                      }
                      return URL.parseUrl(_url.origin + _path);
                  }
                  throw new SyntaxError("Failed to construct 'URL': Invalid URL");
              }
          }
docs: Constructor