updateStateV4.js

const getResponseJson = async response => response.json();

function updateState(dispatch) {
  const dispatchStatus = status => dispatch(SET_STATUS({ status }));
  const dispatchError = e =>
    dispatch(SET_STATUS({ status: 'error', message: e.message }));
  const dispatchState = data => dispatch(SET_STATE({ data }));

  dispatchStatus('submitting');

  return fetch('https://example.com/api/a')
    .then(() => dispatchStatus('processing'))
    .then(() => fetch('https://example.com/api/b'))
    .then(getResponseJson)
    .then(dispatchState)
    .catch(dispatchError)
    .finally(() => dispatchStatus('finished'));
}