getByIndex(target, index, navItems) {
    if (navItems.length === 0) {
      return;
    }

    const item = navItems[index];

    if (item && (target === item.id || target === item.href)) {
      return item;
    } else {
      let result;

      for (let i = 0; i < navItems.length; ++i) {
        result = this.getByIndex(target, index, navItems[i].subitems);

        if (result) {
          break;
        }
      }

      return result;
    }
  }
Get an item from navigation subitems recursively by index
@param  {string} target
@param  {number} index
@param  {array} navItems
@return {object} navItem