cachedPokemonCall-3.js

const request = require('request');
const NodeCache = require('node-cache');
const API_ENDPOINT = 'http://pokeapi.co/api/v2/pokemon/';
const cache = new NodeCache();

// accepts an endpoint (string) to query
// accepts a callback function to be called when the query is finished
function callEndpoint(endpoint, callback) {
  request(endpoint, (error, response, body) => {
    // if unsuccessful, pass the error to the callback function
    if (error || response.statusCode !== 200) return callback(error, null);
    
     // if successful, store the body in the cache
    cache.set(endpoint, body, (err, success) => {
      // if unsuccessful, pass the error to the callback function
      if (err || !success) return callback(err, null);
      
      // if successful, pass no error and the request body to the callback function
      return callback(null, body);
    });
  });
}

// accepts an endpoint (string) to query
// accepts a callback function to be called when the query is finished
function requestCache(endpoint, callback) {
  // try getting cached data from the cache first
  cache.get(endpoint, (err, cachedData) => {
    
    // if there's an error, pass the error to the callback function
    if (err) return callback(err, null);
    // if there's cached data, pass no error and the cached data to the callback function
    if (cachedData) return callback(null, cachedData);
    // if no error and data was not found, make the API request and pass the callback function
    callEndpoint(endpoint, callback);
    
  });
}

// Calling requestCache with the PokeAPI endpoint. Note how this is similar to how request is called
requestCache(API_ENDPOINT, (err, data) => console.log(data));