more-promise.js

process.on('uncaughtException', (e) => {
  console.log('XXXX UNCAUGHT EXCEPTION XXXX');
});

process.on('unhandledRejection', (e) => {
  console.log('XXXX UNHANDLED REJECTION XXXX');
});

const newError = (name = 'GenericError', message =  'error messaage') => {
  const e = new Error(message);
  e.name = name;
  return e;
};

const makeReq = ({ ok = true, statusCode = 200, body = {} } = {}) =>
  ({ ok, statusCode, body });

logInfo = data => {
  console.log('INFO', data);
  return data;
};

logError = error => {
  console.error(`handled: ${error.name || 'some error'}`);
  return error;
};

const throwFactory = (t, name, message) => response => {
  if (t(response))
    throw newError(name, message);
  return response;
};

const rejectIfNotOk = throwFactory(
  response => response.ok !== true,
  'HTTPStatusError',
  'response not ok'
);

const rejectIfNotLoggedIn = throwFactory(
  response => Boolean(response.body && response.body.reloginUrl),
  'UserNotLoggedIn',
  'user not logged in'
);

const throwNetworkError = r => {
  const e = newError('PromiseRejected', 'Promise rejection error');
  return Promise.reject(e);
};

const validateResponse = response => (
  Promise.resolve(response)
    .then(rejectIfNotOk)
    .then(rejectIfNotLoggedIn)
);

const req = {
  okTrue: () => Promise.resolve(makeReq()),
  okFalse: () => Promise.resolve(makeReq({ ok: false, statusCode: 400 })),
  reject: e => Promise.reject(e || {}),
  notLoggedIn: () => Promise.resolve(makeReq({
    body: { success: true, reloginUrl: '/login' }
  }))
};

req.okTrue().then(validateResponse).then(logInfo).catch(logError);
req.okFalse().then(validateResponse).then(logInfo).catch(logError);
req.reject(newError('ReqRejected')).then(validateResponse).catch(logError);
req.notLoggedIn().then(validateResponse).then(logInfo).catch(logError);