JS:菲波那切数列--闭包实现

function fibonacci(n) {
  if (n === 0) {
    return n
  } else {
    var fibo;
    var _f = (function () {
      var result;
      var res1 = 1;
      var res2 = 1;
      return function() {
        result = res1;
        res1 = res2;
        res2 = result + res2;
        return result;
      }
    })()
    for (var i = 1; i <= n + 1; i++) {
      if (i === n + 1) {
        fibo = _f();
      } else 
        _f();
    }
    return fibo;
  }
}

console.log(fibonacci(10));