Backport PR #6653

---------

**Commit 1:**
[internal] Replace empty var declaration with let

Any time there is a variable defined in a JS file without also storing a
value in it, we know that definition cannot be converted to a const, so
we convert it to a let.

For example:

`var blah;` becomes `let blah;`

Some of these things variables might be unused, and many others can
likely be switched to const with only minor refactoring, but the commit
is very large, so there are no changes in it other than the 1:1 switch.

* Original sha: bfc59e9
* Authored by Court Ewing <court@epixa.com> on 2016-03-24T22:27:29Z

src/cli/plugin/__tests__/setting_parser.js

@@ -70,8 +70,8 @@ describe('kibana cli', function () {
 
       describe('parse function', function () {
 
-        var options;
-        var parser;
+        let options;
+        let parser;
         beforeEach(function () {
           options = { install: 'dummy/dummy', pluginDir: fromRoot('installedPlugins') };
         });

src/server/config/__tests__/config.js

@@ -62,7 +62,7 @@ describe('lib/config/config', function () {
 
     describe('#resetTo(object)', function () {
 
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });
@@ -79,7 +79,7 @@ describe('lib/config/config', function () {
 
     describe('#has(key)', function () {
 
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });
@@ -99,7 +99,7 @@ describe('lib/config/config', function () {
     });
 
     describe('#set(key, value)', function () {
-      var config;
+      let config;
 
       beforeEach(function () {
         config = new Config(schema);
@@ -148,7 +148,7 @@ describe('lib/config/config', function () {
 
     describe('#get(key)', function () {
 
-      var config;
+      let config;
 
       beforeEach(function () {
         config = new Config(schema);
@@ -187,7 +187,7 @@ describe('lib/config/config', function () {
     });
 
     describe('#extendSchema(key, schema)', function () {
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });

src/server/config/flattenWith.js

@@ -1,6 +1,6 @@
 var _ = require('lodash');
 module.exports = function (dot, nestedObj, flattenArrays) {
-  var key; // original key
+  let key; // original key
   var stack = []; // track key stack
   var flatObj = {};
   (function flattenObj(obj) {

src/server/status/__tests__/ServerStatus.js

@@ -7,8 +7,8 @@ var Status = require('../Status');
 var ServerStatus = require('../ServerStatus');
 
 describe('ServerStatus class', function () {
-  var server;
-  var serverStatus;
+  let server;
+  let serverStatus;
 
   beforeEach(function () {
     server = { expose: sinon.stub(), log: sinon.stub() };

src/server/status/__tests__/Status.js

@@ -5,8 +5,8 @@ var ServerStatus = require('../ServerStatus');
 
 describe('Status class', function () {
 
-  var server;
-  var serverStatus;
+  let server;
+  let serverStatus;
 
   beforeEach(function () {
     server = { expose: sinon.stub(), log: sinon.stub() };

src/ui/public/Binder/__tests__/Binder.js

@@ -6,7 +6,7 @@ var ngMock = require('ngMock');
 var Binder = require('ui/Binder');
 
 describe('Binder class', function () {
-  var $scope;
+  let $scope;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function ($rootScope) {

src/ui/public/IndexedArray/IndexedArray.js

@@ -75,7 +75,7 @@ define(function (require) {
 
       var from = pathGetter.partial(prop).value();
       var to = inflect(prop);
-      var cache;
+      let cache;
 
       Object.defineProperty(self, to, {
         enumerable: false,

src/ui/public/IndexedArray/__tests__/IndexedArray.js

@@ -21,7 +21,7 @@ users.inIdOrder = _.sortBy(users, 'id');
 
 describe('IndexedArray', function () {
   describe('Basics', function () {
-    var reg;
+    let reg;
 
     beforeEach(function () {
       reg = new IndexedArray();

src/ui/public/IndexedArray/inflector.js

@@ -17,7 +17,7 @@ define(function (require) {
 
   function inflector(prefix, postfix) {
     return function inflect(key) {
-      var inflected;
+      let inflected;
 
       if (key.indexOf('.') !== -1) {
         inflected = key

src/ui/public/StackTraceMapper/stackLineFormat.js

@@ -5,7 +5,7 @@ var opts = [
   /(?: \(|at )((?:[!#$&-;=?-\[\]_a-z~]|%[0-9a-f]{2})+\.js)\:(\d+)(?:\:(\d+)|())/ig
 ];
 
-var sample;
+let sample;
 try { throw new Error('msg'); } catch (e) { sample = e.stack; }
 
 var format = _.find(opts, function (format) {

src/ui/public/Vis/AggConfig.js

@@ -141,7 +141,7 @@ define(function (require) {
      */
     AggConfig.prototype.resetParams = function () {
       var fieldParam = this.type && this.type.params.byName.field;
-      var field;
+      let field;
 
       if (fieldParam) {
         var prevField = this.params.field;

src/ui/public/Vis/AggConfigs.js

@@ -48,8 +48,8 @@ define(function (require) {
 
     AggConfigs.prototype.toDsl = function () {
       var dslTopLvl = {};
-      var dslLvlCursor;
-      var nestedMetrics;
+      let dslLvlCursor;
+      let nestedMetrics;
 
       if (this.vis.isHierarchical()) {
         // collect all metrics, and filter out the ones that we won't be copying
@@ -85,7 +85,7 @@ define(function (require) {
         }
 
         var dsl = dslLvlCursor[config.id] = config.toDsl();
-        var subAggs;
+        let subAggs;
 
         if (config.schema.group === 'buckets' && i < list.length - 1) {
           // buckets that are not the last item in the list accept sub-aggs

src/ui/public/Vis/__tests__/_AggConfig.js

@@ -3,11 +3,11 @@ describe('AggConfig', function () {
   var expect = require('expect.js');
   var ngMock = require('ngMock');
 
-  var Vis;
-  var AggType;
-  var AggConfig;
-  var indexPattern;
-  var fieldFormat;
+  let Vis;
+  let AggType;
+  let AggConfig;
+  let indexPattern;
+  let fieldFormat;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/Vis/__tests__/_AggConfigResult.js

@@ -4,9 +4,9 @@ describe('AggConfigResult', function () {
   var expect = require('expect.js');
   var ngMock = require('ngMock');
 
-  var AggConfig;
-  var indexPattern;
-  var Vis;
+  let AggConfig;
+  let indexPattern;
+  let Vis;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/Vis/__tests__/_AggConfigs.js

@@ -4,13 +4,13 @@ describe('AggConfigs', function () {
   var expect = require('expect.js');
   var ngMock = require('ngMock');
 
-  var Vis;
-  var IndexedArray;
-  var AggConfig;
-  var AggConfigs;
-  var SpiedAggConfig;
-  var indexPattern;
-  var Schemas;
+  let Vis;
+  let IndexedArray;
+  let AggConfig;
+  let AggConfigs;
+  let SpiedAggConfig;
+  let indexPattern;
+  let Schemas;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {
@@ -95,7 +95,7 @@ describe('AggConfigs', function () {
     });
 
     describe('defaults', function () {
-      var vis;
+      let vis;
       beforeEach(function () {
         vis = {
           indexPattern: indexPattern,

src/ui/public/Vis/__tests__/_Renderbot.js

@@ -1,5 +1,5 @@
 describe('renderbot', function () {
-  var Renderbot;
+  let Renderbot;
   var expect = require('expect.js');
   var ngMock = require('ngMock');
 
@@ -12,10 +12,10 @@ describe('renderbot', function () {
   }
 
   describe('API', function () {
-    var vis;
-    var $el;
-    var renderbot;
-    var uiState;
+    let vis;
+    let $el;
+    let renderbot;
+    let uiState;
 
     beforeEach(init);
     beforeEach(function () {

src/ui/public/Vis/__tests__/_Vis.js

@@ -4,11 +4,11 @@ describe('Vis Class', function () {
   var ngMock = require('ngMock');
   var expect = require('expect.js');
 
-  var indexPattern;
-  var Vis;
-  var visTypes;
+  let indexPattern;
+  let Vis;
+  let visTypes;
 
-  var vis;
+  let vis;
   var stateFixture = {
     type: 'pie',
     aggs: [

src/ui/public/agg_response/geo_json/__tests__/geo_json.js

@@ -4,11 +4,11 @@ var expect = require('expect.js');
 var ngMock = require('ngMock');
 
 describe('GeoJson Agg Response Converter', function () {
-  var vis;
-  var tabify;
-  var convert;
-  var esResponse;
-  var aggs;
+  let vis;
+  let tabify;
+  let convert;
+  let esResponse;
+  let aggs;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {
@@ -103,10 +103,10 @@ describe('GeoJson Agg Response Converter', function () {
         describe('includes one feature per row in the table', function () {
           this.timeout(60000);
 
-          var table;
-          var chart;
-          var geoColI;
-          var metricColI;
+          let table;
+          let chart;
+          let geoColI;
+          let metricColI;
 
           before(function () {
             table = makeTable();

src/ui/public/agg_response/hierarchical/__tests__/array_to_linked_list.js

@@ -4,7 +4,7 @@ var expect = require('expect.js');
 describe('buildHierarchicalData()', function () {
   describe('arrayToLinkedList', function () {
 
-    var results;
+    let results;
     beforeEach(function () {
       results = arrayToLinkedList([
         { id: 1 },

src/ui/public/agg_response/hierarchical/__tests__/build_hierarchical_data.js

@@ -5,11 +5,11 @@ var sinon = require('auto-release-sinon');
 var expect = require('expect.js');
 var ngMock = require('ngMock');
 
-var Vis;
-var Notifier;
-var AggConfigs;
-var indexPattern;
-var buildHierarchicalData;
+let Vis;
+let Notifier;
+let AggConfigs;
+let indexPattern;
+let buildHierarchicalData;
 
 describe('buildHierarchicalData', function () {
 
@@ -27,8 +27,8 @@ describe('buildHierarchicalData', function () {
 
 
   describe('metric only', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -99,8 +99,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('threeTermBuckets', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -141,8 +141,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneHistogramBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -173,8 +173,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneRangeBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -214,8 +214,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneFilterBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -250,8 +250,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneFilterBucket that is a split', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;

src/ui/public/agg_response/hierarchical/__tests__/collect_branch.js

@@ -3,7 +3,7 @@ var _ = require('lodash');
 var collectBranch = require('ui/agg_response/hierarchical/_collect_branch');
 var expect = require('expect.js');
 describe('collectBranch()', function () {
-  var results;
+  let results;
   var convert = function (name) {
     return 'converted:' + name;
   };