Reducing Javascript Recursion, and Other Fun Tricks

Here's some brain candy for all you algorith-maniacs (that's right, I said it) out there. Check out Speed up your JavaScript, Part 2.

My favorite is Doug Crockford's memoization function, which can dramatically reduce recursive calls in cases such as this:

/*
 * Normal recursion; whole lotta recursive calls
 */
function fibonacci (n) {
    return n < 2 ? n :
            fibonacci(n - 1) +
            fibonacci(n - 2);
};

/*
 * Cached recursion; called once for each value of n
 */
function memoizer(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;
};

He then applies this to the Fibonacci sequence generator:

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