fib.js

const assert = require('assert');

const naiveFib = n => {
	if (n === 1 || n === 2) return 1;

	return naiveFib(n - 1) + naiveFib(n - 2);
};

console.time("naive");
assert(naiveFib(45) === 1134903170);
console.timeEnd("naive");
// => 9757.694ms

const memoFib = (n, memo = [0, 1, 1]) => {
	if (!memo[n]) {
		memo[n] = memoFib(n - 1, memo) + memoFib(n - 2, memo);
	}

	return memo[n];
};

console.time("memo");
assert(memoFib(45) === 1134903170);
console.timeEnd("memo");
// => 0.057ms