Fibonacci

fibonacci.js

/*
Slow way
*/

var utils = {
  fibonacci: function(n) {
    if (n === 0) {
      return 0;
    }
    if (n === 1) {
      return 1;
    } else {
      return this.fibonacci(n - 1) + this.fibonacci(n - 2);
    }
  }
};



/*
Fast way
If you don't have an Array then you save on memory and .push calls
*/

var utils = {
    fibonacci: function(n) {
      var a = 0,
          b = 1,
          c;

      if (n < 3) {
        if (n < 0) return fib(-n);
        if (n === 0) return 0;
        return 1;
      }
      while (--n) {
        c = a + b, a = b, b = c;
      }
      return c;
  }
};