JS Memoization

sample.js

// Simple memoization which only handles a single argument
// There's lots of things wrong with this code,
//   like that it doesn't handle falsy values, for example.
// See below for a good discussion on memoization:
//   http://addyosmani.com/blog/faster-javascript-memoization
Function.prototype.memoize = function() {
  var fn = this,
      cache = {};
  return function(arg) {
    if(!cache[arg]) {
      cache[arg] = fn.call(null, arg);
    }
    return cache[arg];
  };
};

function fibonaci(n) {
  return n < 2 ? 1 : fibonaci(n - 1) + fibonaci(n - 2);
}

function beersOnAWall(n) {
  return console.log(fibonaci(n) + " beers on a wall...");
}

var d = new Date();
beersOnAWall(25);
console.log((new Date().getTime() - d.getTime()) + "ms");
fibonaci = fibonaci.memoize();
d = new Date();
beersOnAWall(25);
console.log((new Date().getTime() - d.getTime()) + "ms");
// 121393 beers on a wall...
// 128ms
// 121393 beers on a wall...
// 1ms
// ...with 32...
// 3524578 beers on a wall...
// 3725ms
// 3524578 beers on a wall...
// 2ms
// ...with 35 the non-memoized received script timeouts
// 14930352 beers on a wall...
// 2ms
// ...1000?!?...
// 7.0330367711422765e+208 beers on a wall...
// 4ms
// That's a lot of beer.