code: function(req, res) {
          if (!searchIdx) return res();
          var results = searchIdx.search(req.term)
            .map(function(result) {
              return {
                label: files[result.ref].title,
                value: files[result.ref]
              };
            });
  
          res(results);
        }
docs: use lunr search index to find a page based on specified search term