Polling pattern using redux-saga

redux-saga-poll.js

export default function* defaultSaga() {
  // ...
  // The polling will start only after the first CHECK_BALANCES ends
  yield [
    fork(watchPollData),
    takeLatest(CHECK_BALANCES, checkAllBalances),
  ];
}

// Start Polling when first call to checkAllBalances succeded or fails
// Wait for successful response or fail, then fire another request
// Cancel polling on STOP_POLL_BALANCES
function* watchPollData() {
  while (true) {
    yield take([CHECK_BALANCES_SUCCESS, CHECK_BALANCES_ERROR]);
    yield race([
      call(pollData),
      take(STOP_POLL_BALANCES),
    ]);
  }
}

// Fetch data every timeBetweenCheckBalances seconds
function* pollData() {
  yield call(delay, timeBetweenCheckBalances);
  yield put(checkBalances());
}

// Utility function for delay effects
function delay(millisec) {
  return new Promise(resolve => setTimeout(() => resolve(true), millisec));
}