memoized_fibonacci

memoized_fibonacci.js

var fibonacci = function(){
  var _cache = [];
  
  var fib = function(i){
      if (i < 0) {
         console.err('invalid input. i must be >= 0');
         return;
      }
      if (i < 2) {
         _cache[i] = i;
         return _cache[i];
      }
      if (!_cache[i]) {
          _cache[i] = fib(i-1) + fib(i-2);
      }
      return _cache[i];            
  };
  return fib;
}

var cachedFibonacci = fibonacci();
// usage
// cachedFibonacci(0) === 0
// cachedFibonacci(1) === 1
// cachedFibonacci(3) === 2
// cachedFibonacci(6) === 8