JStGP memoization.js

var fibonacci = function () {
    var memo = [0, 1];
    var fib = function (n) {
        var result = memo[n];
        if (typeof result !== 'number') {
            result = fib(n-1) + fib(n-2);
            memo[n] = result;
        }
        return result;
    }
    return fib;
}();

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;
};