get(target) {
    var index;

    if (!target) {
      return this.toc;
    }

    if (target.indexOf("#") === 0) {
      index = this.tocById[target.substring(1)];
    } else if (target in this.tocByHref) {
      index = this.tocByHref[target];
    }

    return this.getByIndex(target, index, this.toc);
  }
Get an item from the navigation
@param  {string} target
@return {object} navItem