Usage

import memoize from "extensible-memoize";
const getItem = memoize(fetchItem);

//define your fetch function:
function fetchItem(key: K): Promise<V> {
  //fetch the item identified by key
}

Note: K must be one of void, string, or extends {hashKey: string} (an object with a hashKey property)

Caching

By default, memoize uses a mem cache with no expiration. To specify your own caching implementation, pass an array of Caches as the second parameter.

interface Cache<K, V> {
  get: (key: K) => Promise<V>
  set: (key: K, value: V) => Promise<void>
}

const getItem = memoize(fetchItem, [cache1, cache2, ...]);

Memoize will first look for the item in cache1, then in cache2, and so on. If the item is not found in the caches, fetchItem will be called. Note that your cache implementations do not have to worry about dealing with concurrency, memoize will take care of that.