axios caching

server.js

//
// Cache the response of an axios request
//

const cacheRequest = request => {
  let cache = null;
  return () => {
    cache = cache || request.then(({ data }) => data);
    return cache;
  };
};

//
// Expensive requests used in multiple calculations
//

const getSystemCosts = cacheRequest(axios.get(endpoints.systemCosts));
const getAdjustedPrices = cacheRequest(axios.get(endpoints.marketPrices));

//
// Add adjusted price for each item for job cost calculation
//

const injectAdjustedPrice = types => {
  return new Promise(resolve => {
    getAdjustedPrices().then(prices => {
      prices.forEach(({ type_id: id, adjusted_price }) => {
        if (types[id] && types[id].outputs) {
          types[id].adjusted_price = adjusted_price;
        }
      });
      resolve(types);
    });
  });
};