Memoize.js

// Main Memoize function
const memo = fn => {
  const cache = {}
  return function () {
    const key = JSON.stringify(arguments);
    if(key in cache){
      return cache[key]
    } else {
      cache[key] = fn.apply(this, arguments);
      return cache[key]
    }
  }
}

// Example #1
const factorial = memo( n => {
  console.log("calculating for:",n)
  return n > 1 ? factorial(n-1) * n : 1
})
console.log(factorial(4))
console.log(factorial(5))

// Example #2
// var fib = memo(function(n){
//   if (n < 2){
//      return 1;
//    }else{
//      console.log("loading...");
//      return fib(n-2) + fib(n-1);
//    }
// });
// console.log(fib(3))
// console.log(fib(4))