Memoization

Memoize

function memoize(func) {
  var cache = {};
  
  return function(n) {
    if (cache.hasOwnProperty(n)) {
      return cache[n];
    }
    
    var result = func(n);
    cache[n] = result;
    return result;
  }
}

Memoized

var cache = {};

function fibonacci(n) {
  if (cache.hasOwnProperty(n)) {
    return cache[n];
  }
  
  if (n <= 1) {
    return 1;
  } else {
    var result = fibonacci(n - 1) + fibonacci(n - 2);
    cache[n] = result;
    return result;
  }
};

Memoized (general)

function memoize(func, hash) {
  var cache = {};
  
  return function() {
    var key = hash(arguments);
    
    if (cache.hasOwnProperty(key)) {
      return cache[key];
    }
    
    var result = func(key);
    cache[key] = result;
    return result;
  }
}

var memoizedFibonacci = memoize(fibonacci, args => args[0);

Naive

function fibonacci(n) {
  if (n <= 1) {
    return 1;
  }
  
  return fibonacci(n - 1) + fibonacci(n - 2);
}