Making 1000 requests without angering the remote server

market.js

const ordersEpic = (action$, state$) => action$.pipe(
  // Listen for this action
  ofType(type.GET_ORDERS), 

  // Replace the action with the list of active IDs
  mapTo(state$.value.market.ids), 

  // Turn the list into a stream of ids
  flatMap(from), 

  // Add a 1 second delay to each emit
  concatMap(id => of(id).pipe(delay(1000))), 

  // Replace the id with the http response for orders of that id
  switchMap(id => ajax(endpoints.orders(10000002, id)) 
    .pipe(map(({ response }) => response))),
  
  // Send the orders to state storage
  map(setOrders)
);