利用ES6的Generator语法实现自定义iterator

var fakeArray = {
  _values: [1, 2, 3, 4, 5, 6],
  [Symbol.iterator]() {

    var _values = this._values;
    var _index = 0;

    var done = function(){
       return _index >= _values.length;
    };

    var iter = {
      next() {
        console.log("Jerry's own iterator, current index: " + _index);
        var it = {
          value: _values[_index],
          done: done() 
        }; 
        if (!it.done) {
          _index++;
        }
        return it;
      } 
    }; 
    return iter;
  }
}

for (var n of fakeArray) {
  console.log(n)
}