另类递归

        var memoizer = function (memo, fundamental) {

            var shell = function (n) {

                var result = memo[n];

                if (typeof result !== 'number') {

                    result = fundamental(shell, n);

                    memo[n] = result;

                }

 

                return result;

            };

 

            return shell;

        };

        var fibonacci = memoizer([1, 1], function (shell, n) {

            return shell(n - 1) + shell(n - 2);

        });

        var factorial = memoizer([1, 1], function (shell, n) {

            return n * shell(n - 1);

        });

       

 

        function test(n) {

            for (var i = 1; i <= n; i++) {

                fibonacci(n);

                factorial(n);

            }

        }

说明： 当执行test（n）时，该思路就能大幅提升性能！