fib.js

var memoizer = function(memo, func) {
	var recur = function(n) {
		var result = memo[n];
		if (typeof result !== 'number') {
			result = func(recur, n);
			memo[n] = result;
		}
		return result;
	};
	return recur;
};

var fibonacci = memoizer([0, 1], function(recur, n) {
	return recur(n - 1) + recur(n - 2);
});

var factorial = memoizer([1, 1], function(recur, n) {
	return n * recur(n - 1);
});

console.log('fibonacci(3):', fibonacci(3));
console.log('factorial(10):', factorial(10));