optimization-with-caching.js

// Task 1: Write a function, times10, that takes an argument, n, and multiples n times 10
// a simple multiplication fn
const times10 = (n) => (n * 10);

console.log('~~~~~~~~~~~~~~TASK 1~~~~~~~~~~~~~~');
console.log('times10 returns:', times10(9));

// Task 2: Use an object to cache the results of your times10 function. 
// protip 1: Create a function that checks if the value for n has been calculated before.
// protip 2: If the value for n has not been calculated, calculate and then save the result in the cache object.

const cache = {};

const memoTimes10 = (n) => {
  if (n in cache) {
			console.log('Fetching from cache:', n);
			return cache[n];
		} else {
			console.log('Calculating result');
			let result = times10(n); //90
			cache[n] = result; 
			return result;
		}
};

console.log('~~~~~~~~~~~~~~TASK 2~~~~~~~~~~~~~~');
console.log('Task 2 calculated value:', memoTimes10(9));	// calculated
console.log('Task 2 cached value:', memoTimes10(9));	// cached

// Task 3: Clean up your global scope by moving your cache inside your function.
// protip: Use a closure to return a function that you can call later.
const memoizedClosure = () => {
  let cache = {};
	return (n) => {
		if (n in cache) {
			console.log('Fetching from cache:', n);
			return cache[n];
		}
		else {
			console.log('Calculating result');
			let result = times10(n);
			cache[n] = result;
			return result;
		}
	};
};

// returned function from memoizedAdd
const memoClosureTimes10 = memoizedClosure();
console.log('~~~~~~~~~~~~~~TASK 3~~~~~~~~~~~~~~');
console.log('Task 3 calculated value:', memoClosureTimes10(9));	// calculated
console.log('Task 3 cached value:', memoClosureTimes10(10));	// cached

// Task 4: Make your memo function generic and accept the times10 function as a callback rather than defining the n * 10 logic inside the if/else or pulling it in from the global scope.

// protip: Take advantage of the fact that parameters are saved in the closure as well, just like the cache from the previous example.
const memoize = (cb) => {
  let cache = {};
	return (n, ...args) => { //[9]
		if (n in cache) {
			console.log('Fetching from cache:', n);
			return cache[n];
		}
		else {
			console.log('Calculating result');
			let result = cb(n, ...args); // cb(9)
			cache[n] = result;
			return result;
		}
	};
};

// returned function from memoizedAdd
const memoizedTimes10 = memoize(times10);
// console.log('~~~~~~~~~~~~~~TASK 4~~~~~~~~~~~~~~');
console.log('Task 4 calculated value:', memoizedTimes10(9));	// calculated
console.log('Task 4 cached value:', memoizedTimes10(9));	// cached