window.addEventListener('load', function() {
	var modules = {};
	modules['Memoizator'] = (function(modules) {
		return {
		  memoize: memoize
		};

		function memoize(f) {
		  var cache = {};
		  return function(n) {
		    if(cache[n] == undefined) {
		      cache[n] = f(n);
		    }
		    return cache[n];
		  };
		}

	})();
	modules['Math.Fibonacci'] = (function(memoize, modules) {
		var get = memoize(function(n) {
		  if(n < 2) {
		    return 1;
		  } else {
		    return get(n-1) + get(n-2);
		  }
		});

		return {
		  get: get
		};

	})(modules['Memoizator'].memoize);
	(function(nth, modules) {
		var input = document.getElementById('n');
		var latestKnownValidInput = input.value;
		var result = document.getElementById('result');

		input.addEventListener('change', function() {
		  var newValue = input.value;
		  if(isNaN(newValue) || newValue < 0 || newValue.trim().length == 0) {
		    input.value = latestKnownValidInput;
		  }
		  result.textContent = nth(input.value);
		});

	})(modules['Math.Fibonacci'].get);
});