Since you are already using redux you can apply redux-thunk middleware which allows you to define async actions.
Installation & usage: Redux-thunk
export function fetchBook(id) {
return dispatch => {
dispatch(setLoadingBookState()); // Show a loading spinner
fetch(`/book/${id}`, (response) => {
dispatch(doneFetchingBook()); // Hide loading spinner
if(response.status == 200){
dispatch(setBook(response.json)); // Use a normal function to set the received state
}else {
dispatch(someError)
}
})
}
}
function setBook(data) {
return { type: 'SET_BOOK', data: data };
}