Optimization - Memoization

optimization-memoization.js

const memoize = (callback, limit = 100, delimiter = "\u00B7") => {
  if (typeof callback !== "function") {
    throw new TypeError("Memoize expects a function");
  }
  const cache = new Map();
  return (...args) => {
    const cacheKey = args.join(delimiter); // To get key without collision

    if (cache.has(cacheKey)) {
      console.log(`Retrieving from cache for ${cacheKey}`);
      return cache.get(cacheKey);
    }

    console.log(`******* Calculating result for ${cacheKey} *******`);

    // If cache reach the limit, delete the first (oldest) entry
    if (cache.size >= limit) {
      cache.delete(cache.keys().next().value);
    }
    const result = callback(...args);
    cache.set(cacheKey, result);
    return result;
  };
};

const memoizedFactorial = memoize(function factorial(n) {
  return n <= 1 ? 1 : n * memoizedFactorial(n - 1);
});

console.log(`Factorial of 11: ${memoizedFactorial(11)}`);
console.log(`Factorial of 6: ${memoizedFactorial(3)}`);
console.log(`Factorial of 7: ${memoizedFactorial(3)}`);
console.log(`Factorial of 11: ${memoizedFactorial(11)}`);