memoization.js

function memoize(fn) {
  const cache = new Map();

  return function(...args) {
    const key = args.toString();

    if (cache.has(key)) {
      return cache.get(key);
    }

    const result = fn.apply(this, args);
    cache.set(key, result);

    return result;
  };
}

function add(a, b) {
  return a + b;
}

const memoizedAdd = memoize(add);

console.log(memoizedAdd(2, 3));  // Calculates and caches result
console.log(memoizedAdd(2, 3));  // Returns cached result