function to find the next/prev value in an array (circular)

gistfile1.txt

      return function (_array, _id) {
        var _result = {};
        var _clean_array = _.compact(_array);
        _result.next = _clean_array[($.inArray(_id, _clean_array) + 1) % _clean_array.length];
        _result.prev = _clean_array[($.inArray(_id, _clean_array) - 1 + _clean_array.length) % _clean_array.length];
        return _result;
      };