ES6 Promise try sequence (try cache first then network)

promiseTrySequence.js

function getSomething() {
  let cachePromiseFn = () => {
    return cacheStorage.getItem(CACHE_KEY)
    .then(value => {
      return value && JSON.parse(value);
    });
  };

  let requestPromiseFn = () => {
    return fetch('https://localhost/foo')
    .then(response => response.json())
    .then(response => {
      cacheStorage.setItem(CACHE_KEY, JSON.stringify(response));
      return response;
    });
  };

  let promise = [cachePromiseFn, requestPromiseFn].reduce((currPromise, nextPromiseFn) => {
    return currPromise.then(value => {
      if (value == null) {
        return nextPromiseFn();
      } else {
        return value;
      }
    });
  }, Promise.resolve());

  promise
  .then(value => {
    console.log('We got something from either cache or network request', value)
    return value;
  })
  .catch(error => console.error('getSomething() error - ' + error));
  return promise;
};