How to use the botframework-directlinejs.ConnectionStatus.FailedToConnect function in botframework-directlinejs

break;
          case ConnectionStatus.Online:
            // successfully connected to the converstaion. Connection is healthy so far as we know.
            if (program.verbose) {
              console.log('Connected to DirectLine.');
            }
            if (this.onReadyCb) {
              this.onReadyCb();
            }
            break;
          case ConnectionStatus.ExpiredToken:
            // last operation errored out with an expired token. Your app should supply a new one.
            console.log('DirectLine error: token expired.');
            process.exit(1);
            break;
          case ConnectionStatus.FailedToConnect:
            // the initial attempt to connect to the conversation failed. No recovery possible.
            console.log('DirectLine error: failed to connect.');
            process.exit(1);
            break;
          case ConnectionStatus.Ended:
            // the bot ended the conversation
            break;
        }
      });
  }