Memoizer: takes in any javascript function and adds memoization based on args

memoize.js

var memoize = function memoize(fn) {
  var self = this;

  return function newFn() {
    newFn.__memo || (newFn.__memo = {});
    var args = Array.prototype.slice.call(arguments),
        hash = JSON.stringify(args);

    return (hash in newFn.__memo) 
      ? newFn.__memo[hash] 
      : newFn.__memo[hash] = fn.apply(self, args);
  };
};

function hello(name) {
  return "Hello, "+ name + "! ("+ Date.now() +")";
}

var mello = memoize(hello);

setTimeout(function() {
  console.log(mello('Ben', 'Anderson', 'Boom', function() { return true; }));
  console.log(hello('Ben', 'Anderson', 'Boom'));
}, 500);