checkAppPr: function (port) {
        var result = Promise.defer();
        var checkStatus = function (next, result, times) {
            portscanner.checkPortStatus(port, '127.0.0.1', function (error, status) {
                if (error) {
                    result.reject(error);
                } else {
                    if (status === 'open') {
                        console.log("Application status: open");
                        result.resolve();
                    } else {
                        times--;
                        if (times > 0) {
                            setTimeout(function () {
                                next(next, result, times);
                            }, 1000);
                        } else {
                            result.reject("start timeout");
                        }
                    }
                }
            })
        }
        checkStatus(checkStatus, result, 20);
        return result.promise;
    }

// Returns a promise that resolves when the port is open
checkPortStatus: function(port, host){
  return new Promise((resolve, reject) => {
    portscanner.checkPortStatus(port, host, function(error, status) {
      if(error)
        reject(error);
      else if(status === 'open')
        resolve(status);
      else
        reject(new Error('Port is not open'));
    });
  });
},

// Your API function
checkAppPort: function(port, retriesLeft) {

  const TIME_BETWEEN_CHECKS = 1000;
  const HOST = '127.0.0.1';
  const RETRIES = 20;

  // Setting a default to retriesLeft
  retriesLeft = retriesLeft === void 0 ? RETRIES : retriesLeft;

  if(!port) throw new Error('Port is required');
  if(retriesLeft === 0) return Promise.reject('Timed Out');

  return new Promise((resolve, reject) => {

    // We call our checker. When it resolves, it calls this promise's resolve.
    // If it rejects, we do added work.
    this.checkPortStatus(port, host).then(resolve, error => {
      setTimeout(() => {

        // Call this function again, with one less retry. However, we hook our
        // resolve and reject to the promise of the new call effectively making
        // a chain when it keeps failing.
        this.checkAppPort(port, retriesLeft - 1).then(resolve, reject);

      }, TIME_BETWEEN_CHECKS);
    });
  });
}