A redux thunk middleware example

loadData.js

function loadData() {
  return (dispatch) => {
    fetch('/a/fake/url')
    .then(response => {
      if (!response.ok) {
        // dispatching a downstream action
        return dispatch(requestFailedAction());
      }
      return response.json();
    })
    .then(data => dispatch(requestSuccessAction(data)))
    .catch(err => dispatch(requestFailedAction())
  }
}