code: function(base_url) {                                                                     // 2074
      if (utils.isSameOriginUrl(base_url)) {                                                                        // 2075
          // If, for some reason, we have SockJS locally - there's no                                               // 2076
          // need to start up the complex machinery. Just use ajax.                                                 // 2077
          return new InfoReceiver(base_url, utils.XHRLocalObject);                                                  // 2078
      }                                                                                                             // 2079
      switch (utils.isXHRCorsCapable()) {                                                                           // 2080
      case 1:                                                                                                       // 2081
          // XHRLocalObject -> no_credentials=true                                                                  // 2082
          return new InfoReceiver(base_url, utils.XHRLocalObject);                                                  // 2083
      case 2:                                                                                                       // 2084
  // <METEOR>                                                                                                       // 2085
  // https://github.com/sockjs/sockjs-client/issues/79                                                              // 2086
          // XDR doesn't work across different schemes                                                              // 2087
          // http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx
          if (utils.isSameOriginScheme(base_url))                                                                   // 2089
              return new InfoReceiver(base_url, utils.XDRObject);                                                   // 2090
          else                                                                                                      // 2091
              return new InfoReceiverFake();                                                                        // 2092
  // </METEOR>                                                                                                      // 2093
      case 3:                                                                                                       // 2094
          // Opera                                                                                                  // 2095
          return new InfoReceiverIframe(base_url);                                                                  // 2096
      default:                                                                                                      // 2097
          // IE 7                                                                                                   // 2098
          return new InfoReceiverFake();                                                                            // 2099
      };                                                                                                            // 2100
  }
docs: 2072 2073