refactor(lint): prefer const over var (#1224)

.eslintrc.yml

@@ -3,8 +3,8 @@ extends:
   - 'eslint:recommended'
   - 'plugin:node/recommended'
   - prettier
-env: 
-  mocha: true 
+env:
+  mocha: true
 plugins:
   - node
   - prettier
@@ -16,4 +16,4 @@ rules:
   no-console: off
   node/no-missing-require: off
   node/no-unpublished-require: off
-
+  prefer-const: error

appengine/headless-chrome/app.js

@@ -39,7 +39,7 @@ app.use(async (req, res) => {
     // [END browser]
   }
 
-  let page = await browser.newPage();
+  const page = await browser.newPage();
   await page.goto(url);
   const imageBuffer = await page.screenshot();
 

appengine/memcached/app.js

@@ -22,7 +22,7 @@ const app = express();
 
 // [START gae_flex_redislabs_memcache]
 // Environment variables are defined in app.yaml.
-let MEMCACHE_URL = process.env.MEMCACHE_URL;
+const MEMCACHE_URL = process.env.MEMCACHE_URL;
 
 const mc = memjs.Client.create(MEMCACHE_URL);
 // [END gae_flex_redislabs_memcache]

appengine/metadata/standard/server.js

@@ -36,8 +36,8 @@ function getProjectId() {
 
 app.get('/', async (req, res, next) => {
   try {
-    let response = await getProjectId();
-    let projectId = response.body;
+    const response = await getProjectId();
+    const projectId = response.body;
     res
       .status(200)
       .send(`Project ID: ${projectId}`)

appengine/pubsub/app.js

@@ -59,9 +59,9 @@ app.post('/', formBodyParser, async (req, res, next) => {
     return;
   }
 
-  let data = Buffer.from(req.body.payload);
+  const data = Buffer.from(req.body.payload);
   try {
-    let messageId = await publisher.publish(data);
+    const messageId = await publisher.publish(data);
     res.status(200).send(`Message ${messageId} sent.`);
   } catch (error) {
     next(error);

appengine/typescript/index.ts

@@ -21,6 +21,6 @@ app.get("/", (req, res) => {
   res.send("🎉 Hello TypeScript! 🎉");
 });
 
-const server: object = app.listen(PORT, () => {
+app.listen(PORT, () => {
   console.log(`App listening on port ${PORT}`);
 });

cloud-sql/postgres/knex/server.js

@@ -152,13 +152,13 @@ async function getVoteCount(knex, candidate) {
 app.get('/', (req, res) => {
   (async function() {
     // Query the total count of "TABS" from the database.
-    let tabsResult = await getVoteCount(knex, 'TABS');
-    let tabsTotalVotes = parseInt(tabsResult[0].count);
+    const tabsResult = await getVoteCount(knex, 'TABS');
+    const tabsTotalVotes = parseInt(tabsResult[0].count);
     // Query the total count of "SPACES" from the database.
-    let spacesResult = await getVoteCount(knex, 'SPACES');
-    let spacesTotalVotes = parseInt(spacesResult[0].count);
+    const spacesResult = await getVoteCount(knex, 'SPACES');
+    const spacesTotalVotes = parseInt(spacesResult[0].count);
     // Query the last 5 votes from the database.
-    let votes = await getVotes(knex);
+    const votes = await getVotes(knex);
     // Calculate and set leader values.
     let leadTeam = '';
     let voteDiff = 0;
@@ -219,7 +219,7 @@ app.post('/', (req, res) => {
         .send(msg)
         .end();
     });
-  let msg = 'Successfully voted for ' + team + ' at ' + timestamp;
+  const msg = 'Successfully voted for ' + team + ' at ' + timestamp;
   res
     .status(200)
     .send(msg)

functions/http/index.js

@@ -99,8 +99,8 @@ exports.helloHttp = (req, res) => {
 exports.parseXML = (req, res) => {
   // Convert the request to a Buffer and a string
   // Use whichever one is accepted by your XML parser
-  let data = req.rawBody;
-  let xmlData = data.toString();
+  const data = req.rawBody;
+  const xmlData = data.toString();
 
   const parseString = require('xml2js').parseString;
 
@@ -151,7 +151,7 @@ exports.uploadFile = (req, res) => {
     fields[fieldname] = val;
   });
 
-  let fileWrites = [];
+  const fileWrites = [];
 
   // This code will process each file uploaded.
   busboy.on('file', (fieldname, file, filename) => {

functions/log/index.js

@@ -61,7 +61,7 @@ function getMetrics(callback) {
   const monitoring = Monitoring.v3().metricServiceApi();
 
   // Create two datestrings, a start and end range
-  let oneWeekAgo = new Date();
+  const oneWeekAgo = new Date();
   oneWeekAgo.setHours(oneWeekAgo.getHours() - 7 * 24);
 
   const options = {

functions/ocr/app/index.js

@@ -122,7 +122,7 @@ function renameImageForSave(filename, lang) {
  * @param {object} event (Node 8+) A Google Cloud Storage File object.
  */
 exports.processImage = event => {
-  let file = event.data || event;
+  const file = event.data || event;
 
   return Promise.resolve()
     .then(() => {

functions/ocr/app/test/index.test.js

@@ -74,7 +74,7 @@ function getSample() {
     );
     stubInstance = Object.assign(stubInstance, mocks);
 
-    let out = {};
+    const out = {};
     out[property] = sinon.stub().returns(stubInstance);
     return out;
   };

functions/sendgrid/test/index.test.js

@@ -115,7 +115,7 @@ function getSample() {
 }
 
 function getMocks() {
-  let req = {
+  const req = {
     headers: {},
     query: {},
     body: {},
@@ -124,7 +124,7 @@ function getMocks() {
     },
   };
   sinon.spy(req, 'get');
-  let res = {
+  const res = {
     headers: {},
     send: sinon.stub().returnsThis(),
     json: sinon.stub().returnsThis(),

functions/speech-to-speech/functions/index.js

@@ -39,7 +39,7 @@ const textToSpeechClient = getTextToSpeechClient();
 const storageClient = getStorageClient();
 
 exports.speechTranslate = functions.https.onRequest((request, response) => {
-  let responseBody = {};
+  const responseBody = {};
 
   validateRequest(request)
     .then(() => {
@@ -70,9 +70,9 @@ exports.speechTranslate = functions.https.onRequest((request, response) => {
       responseBody.transcription = transcription;
       responseBody.gcsBucket = outputBucket;
 
-      let translations = [];
+      const translations = [];
       supportedLanguageCodes.forEach(languageCode => {
-        let translation = {languageCode: languageCode};
+        const translation = {languageCode: languageCode};
         const filenameUUID = uuid();
         const filename = filenameUUID + '.' + outputAudioEncoding.toLowerCase();
         callTextTranslation(languageCode, transcription)

functions/speech-to-speech/functions/test/sample.integration.http.test.js

@@ -123,7 +123,7 @@ describe('Tests that require a GCS bucket', function() {
         fs.readFileSync('responseBody.test.json')
       );
 
-      let deletedFiles = [];
+      const deletedFiles = [];
       // Delete the files created in the successful test.
       for (let i = 0; i < responseBody.translations.length; i++) {
         if (responseBody.translations[i].gcsPath) {

iot/beta-features/gateway/gateway.js

@@ -326,9 +326,9 @@ function unbindDeviceFromAllGateways(
       return;
     }
 
-    let device = res.data;
+    const device = res.data;
     if (device) {
-      let isGateway = device.gatewayConfig.gatewayType === 'GATEWAY';
+      const isGateway = device.gatewayConfig.gatewayType === 'GATEWAY';
 
       if (!isGateway) {
         const listGatewaysForDeviceRequest = {
@@ -345,9 +345,9 @@ function unbindDeviceFromAllGateways(
               return;
             }
 
-            let data = res.data;
+            const data = res.data;
             if (data.devices && data.devices.length > 0) {
-              let gateways = data.devices;
+              const gateways = data.devices;
 
               gateways.forEach(gateway => {
                 const unbindRequest = {
@@ -389,17 +389,17 @@ function unbindAllDevices(client, projectId, cloudRegion, registryId) {
       console.error('Could not list devices', err);
       return;
     }
-    let data = res.data;
+    const data = res.data;
     if (!data) {
       return;
     }
 
-    let devices = data.devices;
+    const devices = data.devices;
 
     if (devices && devices.length > 0) {
       devices.forEach(device => {
         if (device) {
-          let isGateway =
+          const isGateway =
             device.gatewayConfig &&
             device.gatewayConfig.gatewayType === 'GATEWAY';
 
@@ -435,7 +435,7 @@ function listGateways(client, projectId, cloudRegion, registryId) {
       console.log('Could not list devices');
       console.log(err);
     } else {
-      let data = res.data;
+      const data = res.data;
       console.log('Current gateways in registry:');
       data.devices.forEach(function(device) {
         if (
@@ -477,7 +477,7 @@ function listDevicesForGateway(
       console.log(err);
     } else {
       console.log('Current devices bound to gateway: ', gatewayId);
-      let data = res.data;
+      const data = res.data;
       if (data.devices && data.devices.length > 0) {
         data.devices.forEach(device => {
           console.log(`\tDevice: ${device.numId} : ${device.id}`);
@@ -515,7 +515,7 @@ function listGatewaysForDevice(
       console.log(err);
     } else {
       console.log('Current gateways for device:', deviceId);
-      let data = res.data;
+      const data = res.data;
       if (data.devices && data.devices.length > 0) {
         data.devices.forEach(gateway => {
           console.log(`\tDevice: ${gateway.numId} : ${gateway.id}`);
@@ -582,7 +582,7 @@ function listenForConfigMessages(
 
   const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${gatewayId}`;
   console.log(mqttClientId);
-  let connectionArgs = {
+  const connectionArgs = {
     host: mqttBridgeHostname,
     port: mqttBridgePort,
     clientId: mqttClientId,
@@ -594,7 +594,7 @@ function listenForConfigMessages(
   };
 
   // Create a client, and connect to the Google MQTT bridge.
-  let client = mqtt.connect(connectionArgs);
+  const client = mqtt.connect(connectionArgs);
 
   client.on('connect', success => {
     if (!success) {
@@ -627,7 +627,7 @@ function listenForConfigMessages(
   });
 
   client.on('message', (topic, message) => {
-    let decodedMessage = Buffer.from(message, 'base64').toString('ascii');
+    const decodedMessage = Buffer.from(message, 'base64').toString('ascii');
 
     if (topic === `/devices/${gatewayId}/errors`) {
       console.log(`message received on error topic: ${decodedMessage}`);
@@ -661,7 +661,7 @@ function listenForErrorMessages(
 
   const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${gatewayId}`;
   console.log(mqttClientId);
-  let connectionArgs = {
+  const connectionArgs = {
     host: mqttBridgeHostname,
     port: mqttBridgePort,
     clientId: mqttClientId,
@@ -673,7 +673,7 @@ function listenForErrorMessages(
   };
 
   // Create a client, and connect to the Google MQTT bridge.
-  let client = mqtt.connect(connectionArgs);
+  const client = mqtt.connect(connectionArgs);
 
   client.on('connect', success => {
     if (!success) {
@@ -703,7 +703,7 @@ function listenForErrorMessages(
   });
 
   client.on('message', (topic, message) => {
-    let decodedMessage = Buffer.from(message, 'base64').toString('ascii');
+    const decodedMessage = Buffer.from(message, 'base64').toString('ascii');
 
     console.log(`message received on error topic ${topic}: ${decodedMessage}`);
   });
@@ -739,7 +739,7 @@ function sendDataFromBoundDevice(
 
   const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${gatewayId}`;
   console.log(`MQTT client id: ${mqttClientId}`);
-  let connectionArgs = {
+  const connectionArgs = {
     host: mqttBridgeHostname,
     port: mqttBridgePort,
     clientId: mqttClientId,
@@ -751,8 +751,8 @@ function sendDataFromBoundDevice(
   };
 
   // Create a client, and connect to the Google MQTT bridge.
-  let iatTime = parseInt(Date.now() / 1000);
-  let client = mqtt.connect(connectionArgs);
+  const iatTime = parseInt(Date.now() / 1000);
+  const client = mqtt.connect(connectionArgs);
 
   client.on('connect', success => {
     if (!success) {
@@ -863,7 +863,7 @@ function publishAsync(
     var schedulePublishDelayMs = 5000; // messageType === 'events' ? 1000 : 2000;
     setTimeout(function() {
       // [START iot_mqtt_jwt_refresh]
-      let secsFromIssue = parseInt(Date.now() / 1000) - iatTime;
+      const secsFromIssue = parseInt(Date.now() / 1000) - iatTime;
       if (secsFromIssue > tokenExpMins * 60) {
         iatTime = parseInt(Date.now() / 1000);
         console.log(`\tRefreshing token after ${secsFromIssue} seconds.`);