choose-closest-server.js

  chooseClosestServer() {
    // try connecting to every available server, choose the one that answers first
    return new Promise((resolve, reject) => {
      Promise.race(this.availableServers.map((server, index) => this.pingServer(index))).then(fastestServer => {
        if (fastestServer === 'timeout') {
          reject(fastestServer);
          return;
        }
        this.chosenServer = fastestServer;
        // eslint-disable-next-line
        return this.connectToServer(this.availableServers[fastestServer]);
      }).then(() => {
        resolve();
      }).catch(e => {
        console.warn(`error:  ${e}`);
        reject(e);
      });
    });
  }