index.js

/**
 * Copyright 2017 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the 'License');
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an 'AS IS' BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

var PROJECT_ID = ''          // Required - your Firebase project ID
var ALGOLIA_APP_ID = '';     // Required - your Algolia app ID
var ALGOLIA_SEARCH_KEY = ''; // Optional - Only used for unauthenticated search

function unauthenticated_search(query) {

  // [START search_index_unsecure]
  var client = algoliasearch(ALGOLIA_APP_ID, ALGOLIA_SEARCH_KEY);
  var index = client.initIndex('notes');

  // Perform an Algolia search:
  // https://www.algolia.com/doc/api-reference/api-methods/search/
  index
    .search({
      query
    })
    .then(function(responses) {
      // Response from Algolia:
      // https://www.algolia.com/doc/api-reference/api-methods/search/#response-format
      console.log(responses.hits);
    });
  // [END search_index_unsecure]
}

function authenticated_search(query) {
  var client;
  var index;
  // [START search_index_secure]
  // Use Firebase Authentication to request the underlying token
  return firebase.auth().currentUser.getIdToken()
    .then(function(token) {
      // The token is then passed to our getSearchKey Cloud Function
      return fetch('https://us-central1-' + PROJECT_ID + '.cloudfunctions.net/getSearchKey/', {
          headers: { Authorization: 'Bearer ' + token }
      });
    })
    .then(function(response) {
      // The Fetch API returns a stream, which we convert into a JSON object.
      return response.json();
    })
    .then(function(data) {
      // Data will contain the restricted key in the `key` field.
      client = algoliasearch(ALGOLIA_APP_ID, data.key);
      index = client.initIndex('notes');

      // Perform the search as usual.
      return index.search({query});
    })
    .then(function(responses) {
      // Finally, use the search 'hits' returned from Algolia.
      return responses.hits;
    });
  // [END search_index_secure]
}

function search(query) {
  if (!PROJECT_ID) {
    console.warn('Please set PROJECT_ID in /index.js!');
  } else if (!ALGOLIA_APP_ID) {
    console.warn('Please set ALGOLIA_APP_ID in /index.js!');
  } else if (ALGOLIA_SEARCH_KEY) {
    console.log('Performing unauthenticated search...');
    return unauthenticated_search(query);
  } else {
    return firebase.auth().signInAnonymously()
      .then(function() {
        return authenticated_search(query).catch(function(err) {
          console.warn(err);
        });
      }).catch(function(err) {
        console.warn(err);
        console.warn('Please enable Anonymous Authentication in your Firebase Project!');
      });
  }
}

// Other code to wire up the buttons and textboxes.

document.querySelector('#do-add-note').addEventListener('click', function() {
  firebase.firestore().collection('notes').add({
    author: [firebase.auth().currentUser.uid],
    text: document.querySelector('#note-text').value
  }).then(function() {
    document.querySelector('#note-text').value = '';
  });
});

document.querySelector('#do-query').addEventListener('click', function() {
  search(document.querySelector('#query-text').value).then(function(hits) {
    document.querySelector('#results').innerHTML = JSON.stringify(hits, null, 2);
  });
});