Enable prefer-const in the eslint config

.eslintrc.yml

@@ -12,3 +12,4 @@ rules:
   eqeqeq: error
   no-warning-comments: warn
   no-var: error
+  prefer-const: error

package.json

@@ -59,7 +59,8 @@
     "samples-test": "cd samples/ && npm link ../ && npm test && cd ../",
     "test-no-cover": "mocha test/*.js",
     "test": "npm run cover",
-    "system-test": "mocha system-test/*.js --timeout 600000"
+    "system-test": "mocha system-test/*.js --timeout 600000",
+    "fix": "eslint '**/*.js' --fix && npm run prettier"
   },
   "dependencies": {
     "@google-cloud/projectify": "^0.3.0",

samples/concepts.js

@@ -560,7 +560,7 @@ class Metadata extends TestHelper {
         });
 
         console.log('Properties by Kind:');
-        for (let key in propertiesByKind) {
+        for (const key in propertiesByKind) {
           console.log(key, propertiesByKind[key]);
         }
 
@@ -599,7 +599,7 @@ class Metadata extends TestHelper {
         });
 
         console.log('Task property representations:');
-        for (let key in representationsByProperty) {
+        for (const key in representationsByProperty) {
           console.log(key, representationsByProperty[key]);
         }
 

src/v1/datastore_client.js

@@ -132,7 +132,7 @@ class DatastoreClient {
       'allocateIds',
       'reserveIds',
     ];
-    for (let methodName of datastoreStubMethods) {
+    for (const methodName of datastoreStubMethods) {
       this._innerApiCalls[methodName] = gax.createApiCall(
         datastoreStub.then(
           stub =>

test/transaction.js

@@ -119,8 +119,6 @@ describe('Transaction', function() {
     });
 
     it('should localize request function', function(done) {
-      let transaction;
-
       const fakeDataset = {
         request_: {
           bind: function(context) {
@@ -136,7 +134,7 @@ describe('Transaction', function() {
         },
       };
 
-      transaction = new Transaction(fakeDataset);
+      const transaction = new Transaction(fakeDataset);
     });
 
     it('should localize default properties', function() {