memoized function

memoized function.js

// a simple pure function to get a value adding 10
const add = (n) => (n + 10);
console.log('Simple call', add(3));
// a simple memoize function that takes in a function
// and returns a memoized function
const memoize = (fn) => {
  let cache = {};
  return (...args) => {
    let n = args[0];  // just taking one argument here
    if (n in cache) {
      console.log('Fetching from cache');
      return cache[n];
    }
    else {
      console.log('Calculating result');
      let result = fn(n);
      cache[n] = result;
      return result;
    }
  }
}
// creating a memoized function for the 'add' pure function
const memoizedAdd = memoize(add);
console.log(memoizedAdd(3));  // calculated
console.log(memoizedAdd(3));  // cached
console.log(memoizedAdd(4));  // calculated
console.log(memoizedAdd(4));  // cached


=============================================================================
  
  
  // same memoize function from before
const memoize = (fn) => {
  let cache = {};
  return (...args) => {
    let n = args[0];
    if (n in cache) {
      console.log('Fetching from cache', n);
      return cache[n];
    }
    else {
      console.log('Calculating result', n);
      let result = fn(n);
      cache[n] = result;
      return result;
    }
  }
}
const factorial = memoize(
  (x) => {
    if (x === 0) {
      return 1;
    }
    else {
      return x * factorial(x - 1);
    }
  }
);
console.log(factorial(5)); // calculated
console.log(factorial(6)); // calculated for 6 and cached for 5