Memoize - function that memoizes other functions.

memoize.js

/**
 * @param fn - a pure (no side effects) function you want to memoize
 * if you run a memoized function again with the same arguments,
 * it will return the cached result instead of running the computation
 */
const memoize = fn => {
  const cache = {};

  return (...args) => {
    const key = JSON.stringify(args);

    if (key in cache) {
      return cache[key];
    } else {
      const result = fn(...args);
      cache[key] = result;

      return result;
    }
  };
};