[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.

src/server/config/__tests__/config.js

@@ -85,7 +85,7 @@ describe('lib/config/config', function () {
 
     describe('#resetTo(object)', function () {
 
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });
@@ -102,7 +102,7 @@ describe('lib/config/config', function () {
 
     describe('#has(key)', function () {
 
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });
@@ -122,7 +122,7 @@ describe('lib/config/config', function () {
     });
 
     describe('#set(key, value)', function () {
-      var config;
+      let config;
 
       beforeEach(function () {
         config = new Config(schema);
@@ -171,7 +171,7 @@ describe('lib/config/config', function () {
 
     describe('#get(key)', function () {
 
-      var config;
+      let config;
 
       beforeEach(function () {
         config = new Config(schema);
@@ -210,7 +210,7 @@ describe('lib/config/config', function () {
     });
 
     describe('#extendSchema(key, schema)', function () {
-      var config;
+      let config;
       beforeEach(function () {
         config = new Config(schema);
       });

src/server/config/flatten_with.js

@@ -1,6 +1,6 @@
 import _ from '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__/server_status.js

@@ -7,8 +7,8 @@ import Status from '../status';
 import ServerStatus from '../server_status';
 
 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

@@ -4,8 +4,8 @@ import Status from '../status';
 import ServerStatus from '../server_status';
 
 describe('Status class', function () {
-  var server;
-  var serverStatus;
+  let server;
+  let serverStatus;
 
   beforeEach(function () {
     server = { expose: sinon.stub(), log: sinon.stub() };

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

@@ -9,11 +9,11 @@ import AggResponseTabifyTabifyProvider from 'ui/agg_response/tabify/tabify';
 import AggResponseGeoJsonGeoJsonProvider from 'ui/agg_response/geo_json/geo_json';
 
 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) {
@@ -108,10 +108,10 @@ 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 @@ import expect from '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

@@ -9,11 +9,11 @@ import VisAggConfigsProvider from 'ui/vis/agg_configs';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 import AggResponseHierarchicalBuildHierarchicalDataProvider from 'ui/agg_response/hierarchical/build_hierarchical_data';
 
-var Vis;
-var Notifier;
-var AggConfigs;
-var indexPattern;
-var buildHierarchicalData;
+let Vis;
+let Notifier;
+let AggConfigs;
+let indexPattern;
+let buildHierarchicalData;
 
 describe('buildHierarchicalData', function () {
 
@@ -31,8 +31,8 @@ describe('buildHierarchicalData', function () {
 
 
   describe('metric only', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -103,8 +103,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('threeTermBuckets', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -145,8 +145,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneHistogramBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -177,8 +177,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneRangeBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -218,8 +218,8 @@ describe('buildHierarchicalData', function () {
   });
 
   describe('oneFilterBucket', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(function () {
       var id = 1;
@@ -254,8 +254,8 @@ 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 @@ import _ from 'lodash';
 import collectBranch from 'ui/agg_response/hierarchical/_collect_branch';
 import expect from 'expect.js';
 describe('collectBranch()', function () {
-  var results;
+  let results;
   var convert = function (name) {
     return 'converted:' + name;
   };

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

@@ -9,14 +9,14 @@ import VisProvider from 'ui/vis';
 import VisAggConfigsProvider from 'ui/vis/agg_configs';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 
-var AggConfigs;
-var Vis;
-var indexPattern;
+let AggConfigs;
+let Vis;
+let indexPattern;
 
 describe('buildHierarchicalData()', function () {
   describe('createRawData()', function () {
-    var vis;
-    var results;
+    let vis;
+    let results;
 
     beforeEach(ngMock.module('kibana'));
 

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

@@ -5,8 +5,8 @@ import AggResponseHierarchicalTransformAggregationProvider from 'ui/agg_response
 
 describe('buildHierarchicalData()', function () {
   describe('transformAggregation()', function () {
-    var transform;
-    var fixture;
+    let transform;
+    let fixture;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/hierarchical/_array_to_linked_list.js

@@ -1,6 +1,6 @@
 import _ from 'lodash';
 export default function (buckets) {
-  var previous;
+  let previous;
   _.each(buckets, function (bucket) {
     if (previous) {
       bucket._previous = previous;

src/ui/public/agg_response/hierarchical/_hierarchical_tooltip_formatter.js

@@ -21,7 +21,7 @@ export default function HierarchicalTooltipFormaterProvider($rootScope, $compile
       _.forEachRight($tooltipScope.rows, function (row, i, rows) {
         row.spacer = $sce.trustAsHtml(_.repeat(' ', row.depth));
 
-        var percent;
+        let percent;
         if (row.item.percentOfGroup != null) {
           percent = row.item.percentOfGroup;
         }

src/ui/public/agg_response/point_series/__tests__/_add_to_siri.js

@@ -2,7 +2,7 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import AggResponsePointSeriesAddToSiriProvider from 'ui/agg_response/point_series/_add_to_siri';
 describe('addToSiri', function () {
-  var addToSiri;
+  let addToSiri;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_fake_x_aspect.js

@@ -6,11 +6,11 @@ import AggTypesAggTypeProvider from 'ui/agg_types/agg_type';
 import AggResponsePointSeriesFakeXAspectProvider from 'ui/agg_response/point_series/_fake_x_aspect';
 describe('makeFakeXAspect', function () {
 
-  var makeFakeXAspect;
-  var Vis;
-  var AggType;
-  var AggConfig;
-  var indexPattern;
+  let makeFakeXAspect;
+  let Vis;
+  let AggType;
+  let AggConfig;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_get_aspects.js

@@ -9,11 +9,11 @@ import AggResponsePointSeriesGetAspectsProvider from 'ui/agg_response/point_seri
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('getAspects', function () {
 
-  var Vis;
-  var Table;
-  var AggConfig;
-  var indexPattern;
-  var getAspects;
+  let Vis;
+  let Table;
+  let AggConfig;
+  let indexPattern;
+  let getAspects;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {
@@ -24,8 +24,8 @@ describe('getAspects', function () {
     indexPattern = Private(FixturesStubbedLogstashIndexPatternProvider);
   }));
 
-  var vis;
-  var table;
+  let vis;
+  let table;
 
   var date = _.memoize(function (n) {
     return moment().startOf('day').add(n, 'hour').valueOf();

src/ui/public/agg_response/point_series/__tests__/_get_point.js

@@ -5,7 +5,7 @@ import AggResponsePointSeriesGetPointProvider from 'ui/agg_response/point_series
 
 describe('getPoint', function () {
 
-  var getPoint;
+  let getPoint;
 
   var truthFormatted = { fieldFormatter: _.constant(_.constant(true)) };
   var identFormatted = { fieldFormatter: _.constant(_.identity) };
@@ -16,10 +16,10 @@ describe('getPoint', function () {
   }));
 
   describe('Without series aspect', function () {
-    var seriesAspect;
-    var xAspect;
-    var yAspect;
-    var yScale;
+    let seriesAspect;
+    let xAspect;
+    let yAspect;
+    let yScale;
 
     beforeEach(function () {
       seriesAspect = null;
@@ -49,10 +49,10 @@ describe('getPoint', function () {
   });
 
   describe('With series aspect', function () {
-    var row;
-    var xAspect;
-    var yAspect;
-    var yScale;
+    let row;
+    let xAspect;
+    let yAspect;
+    let yScale;
 
     beforeEach(function () {
       row = [ { value: 1 }, { value: 2 }, { value: 3 }];

src/ui/public/agg_response/point_series/__tests__/_get_series.js

@@ -3,7 +3,7 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import AggResponsePointSeriesGetSeriesProvider from 'ui/agg_response/point_series/_get_series';
 describe('getSeries', function () {
-  var getSeries;
+  let getSeries;
 
   var agg = { fieldFormatter: _.constant(_.identity) };
 

src/ui/public/agg_response/point_series/__tests__/_init_x_axis.js

@@ -4,7 +4,7 @@ import ngMock from 'ng_mock';
 import AggResponsePointSeriesInitXAxisProvider from 'ui/agg_response/point_series/_init_x_axis';
 describe('initXAxis', function () {
 
-  var initXAxis;
+  let initXAxis;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_init_y_axis.js

@@ -4,7 +4,7 @@ import ngMock from 'ng_mock';
 import AggResponsePointSeriesInitYAxisProvider from 'ui/agg_response/point_series/_init_y_axis';
 describe('initYAxis', function () {
 
-  var initYAxis;
+  let initYAxis;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_main.js

@@ -11,10 +11,10 @@ describe('pointSeriesChartDataFromTable', function () {
   this.slow(1000);
 
 
-  var pointSeriesChartDataFromTable;
-  var indexPattern;
-  var Table;
-  var Vis;
+  let pointSeriesChartDataFromTable;
+  let indexPattern;
+  let Table;
+  let Vis;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_ordered_date_axis.js

@@ -28,7 +28,7 @@ describe('orderedDateAxis', function () {
     }
   };
 
-  var orderedDateAxis;
+  let orderedDateAxis;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/__tests__/_tooltip_formatter.js

@@ -5,7 +5,7 @@ import ngMock from 'ng_mock';
 import AggResponsePointSeriesTooltipFormatterProvider from 'ui/agg_response/point_series/_tooltip_formatter';
 describe('tooltipFormatter', function () {
 
-  var tooltipFormatter;
+  let tooltipFormatter;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_response/point_series/_get_series.js

@@ -37,7 +37,7 @@ export default function PointSeriesGetSeries(Private) {
     if (multiY) {
       series = _.sortBy(series, function (siri) {
         var firstVal = siri.values[0];
-        var y;
+        let y;
 
         if (firstVal) {
           var agg = firstVal.aggConfigResult.aggConfig;

src/ui/public/agg_response/tabify/__tests__/_buckets.js

@@ -2,7 +2,7 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import AggResponseTabifyBucketsProvider from 'ui/agg_response/tabify/_buckets';
 describe('Buckets wrapper', function () {
-  var Buckets;
+  let Buckets;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {

src/ui/public/agg_response/tabify/__tests__/_get_columns.js

@@ -4,9 +4,9 @@ import AggResponseTabifyGetColumnsProvider from 'ui/agg_response/tabify/_get_col
 import VisProvider from 'ui/vis';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('get columns', function () {
-  var getColumns;
-  var Vis;
-  var indexPattern;
+  let getColumns;
+  let Vis;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {

src/ui/public/agg_response/tabify/__tests__/_integration.js

@@ -7,10 +7,10 @@ import VisProvider from 'ui/vis';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('tabifyAggResponse Integration', function () {
 
-  var Vis;
-  var Buckets;
-  var indexPattern;
-  var tabifyAggResponse;
+  let Vis;
+  let Buckets;
+  let indexPattern;
+  let tabifyAggResponse;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {
@@ -46,12 +46,12 @@ describe('tabifyAggResponse Integration', function () {
   describe('transforms a complex response', function () {
     this.slow(1000);
 
-    var vis;
-    var avg;
-    var ext;
-    var src;
-    var os;
-    var esResp;
+    let vis;
+    let avg;
+    let ext;
+    let src;
+    let os;
+    let esResp;
 
     beforeEach(function () {
       vis = new Vis(indexPattern, {

src/ui/public/agg_response/tabify/__tests__/_response_writer.js

@@ -10,14 +10,14 @@ import VisProvider from 'ui/vis';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('ResponseWriter class', function () {
 
-  var Vis;
-  var Table;
-  var Buckets;
-  var Private;
-  var TableGroup;
-  var getColumns;
-  var indexPattern;
-  var ResponseWriter;
+  let Vis;
+  let Table;
+  let Buckets;
+  let Private;
+  let TableGroup;
+  let getColumns;
+  let indexPattern;
+  let ResponseWriter;
 
   function defineSetup(stubGetColumns) {
     beforeEach(ngMock.module('kibana'));

src/ui/public/agg_response/tabify/__tests__/_table.js

@@ -4,7 +4,7 @@ import ngMock from 'ng_mock';
 import AggResponseTabifyTableProvider from 'ui/agg_response/tabify/_table';
 describe('Table class', function () {
 
-  var Table;
+  let Table;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {

src/ui/public/agg_response/tabify/__tests__/_table_group.js

@@ -2,7 +2,7 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import AggResponseTabifyTableGroupProvider from 'ui/agg_response/tabify/_table_group';
 describe('Table Group class', function () {
-  var TableGroup;
+  let TableGroup;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {

src/ui/public/agg_table/__tests__/_group.js

@@ -8,11 +8,11 @@ import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logsta
 import VisProvider from 'ui/vis';
 describe('AggTableGroup Directive', function () {
 
-  var $rootScope;
-  var $compile;
-  var tabifyAggResponse;
-  var Vis;
-  var indexPattern;
+  let $rootScope;
+  let $compile;
+  let tabifyAggResponse;
+  let Vis;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function ($injector, Private) {
@@ -24,7 +24,7 @@ describe('AggTableGroup Directive', function () {
     $compile = $injector.get('$compile');
   }));
 
-  var $scope;
+  let $scope;
   beforeEach(function () {
     $scope = $rootScope.$new();
   });

src/ui/public/agg_table/__tests__/_table.js

@@ -9,11 +9,11 @@ import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logsta
 import VisProvider from 'ui/vis';
 describe('AggTable Directive', function () {
 
-  var $rootScope;
-  var $compile;
-  var tabifyAggResponse;
-  var Vis;
-  var indexPattern;
+  let $rootScope;
+  let $compile;
+  let tabifyAggResponse;
+  let Vis;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function ($injector, Private) {
@@ -25,7 +25,7 @@ describe('AggTable Directive', function () {
     $compile = $injector.get('$compile');
   }));
 
-  var $scope;
+  let $scope;
   beforeEach(function () {
     $scope = $rootScope.$new();
   });
@@ -134,7 +134,7 @@ describe('AggTable Directive', function () {
   });
 
   describe('aggTable.exportAsCsv()', function () {
-    var origBlob;
+    let origBlob;
     function FakeBlob(slices, opts) {
       this.slices = slices;
       this.opts = opts;

src/ui/public/agg_types/__tests__/agg_params.js

@@ -8,11 +8,11 @@ import AggTypesParamTypesOptionedProvider from 'ui/agg_types/param_types/optione
 import AggTypesParamTypesRegexProvider from 'ui/agg_types/param_types/regex';
 describe('AggParams class', function () {
 
-  var AggParams;
-  var BaseAggParam;
-  var FieldAggParam;
-  var OptionedAggParam;
-  var RegexAggParam;
+  let AggParams;
+  let BaseAggParam;
+  let FieldAggParam;
+  let OptionedAggParam;
+  let RegexAggParam;
 
   beforeEach(ngMock.module('kibana'));
   // stub out the param classes before we get the AggParams

src/ui/public/agg_types/__tests__/agg_type.js

@@ -10,12 +10,12 @@ import AggTypesAggTypeProvider from 'ui/agg_types/agg_type';
 import VisAggConfigProvider from 'ui/vis/agg_config';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('AggType Class', function () {
-  var AggType;
-  var AggParams;
-  var AggConfig;
-  var indexPattern;
-  var fieldFormat;
-  var Vis;
+  let AggType;
+  let AggParams;
+  let AggConfig;
+  let indexPattern;
+  let fieldFormat;
+  let Vis;
 
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/agg_types/__tests__/bucket_count_between.js

@@ -8,12 +8,12 @@ import AggTypesIndexProvider from 'ui/agg_types/index';
 import VisAggConfigProvider from 'ui/vis/agg_config';
 import AggTypesBucketsBucketCountBetweenProvider from 'ui/agg_types/buckets/_bucket_count_between';
 describe('bucketCountBetween util', function () {
-  var indexPattern;
-  var Vis;
-  var visTypes;
-  var aggTypes;
-  var AggConfig;
-  var bucketCountBetween;
+  let indexPattern;
+  let Vis;
+  let visTypes;
+  let aggTypes;
+  let AggConfig;
+  let bucketCountBetween;
 
   // http://cwestblog.com/2014/02/25/javascript-testing-for-negative-zero/
   // works for -0 and +0

src/ui/public/agg_types/__tests__/buckets/_histogram.js

@@ -6,7 +6,7 @@ import AggParamWriterProvider from '../agg_param_writer';
 describe('Histogram Agg', function () {
 
   describe('ordered', function () {
-    var histogram;
+    let histogram;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {
@@ -24,7 +24,7 @@ describe('Histogram Agg', function () {
 
 
   describe('params', function () {
-    var paramWriter;
+    let paramWriter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/_range.js

@@ -11,9 +11,9 @@ describe('Range Agg', function () {
 
   var buckets = values(resp.aggregations[1].buckets);
 
-  var range;
-  var Vis;
-  var indexPattern;
+  let range;
+  let Vis;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/date_histogram.js

@@ -12,16 +12,16 @@ import AggTypesBucketsIntervalOptionsProvider from 'ui/agg_types/buckets/_interv
 describe('AggConfig Filters', function () {
   describe('date_histogram', function () {
 
-    var vis;
-    var agg;
-    var field;
-    var filter;
-    var bucketKey;
-    var bucketStart;
-    var getIntervalStub;
-    var intervalOptions;
+    let vis;
+    let agg;
+    let field;
+    let filter;
+    let bucketKey;
+    let bucketStart;
+    let getIntervalStub;
+    let intervalOptions;
 
-    var init;
+    let init;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private, $injector) {
@@ -84,7 +84,7 @@ describe('AggConfig Filters', function () {
 
     it('extends the filter edge to 1ms before the next bucket for all interval options', function () {
       intervalOptions.forEach(function (option) {
-        var duration;
+        let duration;
         if (option.val !== 'custom' && moment(1, option.val).isValid()) {
           duration = moment.duration(10, option.val);
 

src/ui/public/agg_types/__tests__/buckets/create_filter/date_range.js

@@ -9,10 +9,10 @@ import AggTypesBucketsCreateFilterDateRangeProvider from 'ui/agg_types/buckets/c
 
 describe('AggConfig Filters', function () {
   describe('Date range', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/filters.js

@@ -9,10 +9,10 @@ import AggTypesBucketsCreateFilterFiltersProvider from 'ui/agg_types/buckets/cre
 
 describe('AggConfig Filters', function () {
   describe('filters', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/histogram.js

@@ -9,10 +9,10 @@ import AggTypesBucketsCreateFilterHistogramProvider from 'ui/agg_types/buckets/c
 
 describe('AggConfig Filters', function () {
   describe('histogram', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/ip_range.js

@@ -7,10 +7,10 @@ import AggTypesBucketsCreateFilterIpRangeProvider from 'ui/agg_types/buckets/cre
 describe('AggConfig Filters', function () {
 
   describe('IP range', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/range.js

@@ -7,10 +7,10 @@ import AggTypesBucketsCreateFilterRangeProvider from 'ui/agg_types/buckets/creat
 describe('AggConfig Filters', function () {
 
   describe('range', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/create_filter/terms.js

@@ -7,10 +7,10 @@ import AggTypesBucketsCreateFilterTermsProvider from 'ui/agg_types/buckets/creat
 describe('AggConfig Filters', function () {
 
   describe('terms', function () {
-    var AggConfig;
-    var indexPattern;
-    var Vis;
-    var createFilter;
+    let AggConfig;
+    let indexPattern;
+    let Vis;
+    let createFilter;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/buckets/date_histogram/_editor.js

@@ -7,11 +7,11 @@ import VisProvider from 'ui/vis';
 import AggTypesBucketsIntervalOptionsProvider from 'ui/agg_types/buckets/_interval_options';
 describe('editor', function () {
 
-  var indexPattern;
-  var vis;
-  var agg;
-  var render;
-  var $scope;
+  let indexPattern;
+  let vis;
+  let agg;
+  let render;
+  let $scope;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector, $compile) {
@@ -69,9 +69,9 @@ describe('editor', function () {
   }));
 
   describe('random field/interval', function () {
-    var params;
-    var field;
-    var interval;
+    let params;
+    let field;
+    let interval;
 
     beforeEach(ngMock.inject(function (Private) {
       field = _.sample(indexPattern.fields);
@@ -97,7 +97,7 @@ describe('editor', function () {
   });
 
   describe('interval "auto" and indexPattern timeField', function () {
-    var params;
+    let params;
 
     beforeEach(function () {
       params = render({ field: indexPattern.timeFieldName, interval: 'auto' });

src/ui/public/agg_types/__tests__/buckets/date_histogram/_params.js

@@ -8,13 +8,13 @@ import AggTypesIndexProvider from 'ui/agg_types/index';
 import VisAggConfigProvider from 'ui/vis/agg_config';
 describe('params', function () {
 
-  var paramWriter;
-  var writeInterval;
+  let paramWriter;
+  let writeInterval;
 
-  var aggTypes;
-  var AggConfig;
-  var setTimeBounds;
-  var timeField;
+  let aggTypes;
+  let AggConfig;
+  let setTimeBounds;
+  let timeField;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private, $injector) {

src/ui/public/agg_types/__tests__/controls/number_list.js

@@ -7,9 +7,9 @@ import 'ui/number_list';
 describe('NumberList directive', function () {
 
 
-  var $el;
-  var $scope;
-  var compile;
+  let $el;
+  let $scope;
+  let compile;
 
   function onlyValidValues() {
     return $el.find('[ng-model]').toArray().map(function (el) {

src/ui/public/agg_types/__tests__/index.js

@@ -12,8 +12,8 @@ import AggTypesMetricsMetricAggTypeProvider from 'ui/agg_types/metrics/metric_ag
 describe('AggTypesComponent', function () {
 
   describe('bucket aggs', function () {
-    var bucketAggs;
-    var BucketAggType;
+    let bucketAggs;
+    let BucketAggType;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {
@@ -29,8 +29,8 @@ describe('AggTypesComponent', function () {
   });
 
   describe('metric aggs', function () {
-    var metricAggs;
-    var MetricAggType;
+    let metricAggs;
+    let MetricAggType;
 
     beforeEach(ngMock.module('kibana'));
     beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/param_types/_calculate_interval.js

@@ -7,11 +7,11 @@ import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logsta
 import AggTypesParamTypesCalculateIntervalProvider from 'ui/agg_types/param_types/_calculate_interval';
 
 describe('calculateInterval()', function () {
-  var AggConfig;
-  var indexPattern;
-  var Vis;
-  var createFilter;
-  var calculateInterval;
+  let AggConfig;
+  let indexPattern;
+  let Vis;
+  let createFilter;
+  let calculateInterval;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/agg_types/__tests__/param_types/_field.js

@@ -5,8 +5,8 @@ import AggTypesParamTypesBaseProvider from 'ui/agg_types/param_types/base';
 import AggTypesParamTypesFieldProvider from 'ui/agg_types/param_types/field';
 describe('Field', function () {
 
-  var BaseAggParam;
-  var FieldAggParam;
+  let BaseAggParam;
+  let FieldAggParam;
 
   beforeEach(ngMock.module('kibana'));
   // fetch out deps

src/ui/public/agg_types/__tests__/param_types/_optioned.js

@@ -5,8 +5,8 @@ import AggTypesParamTypesBaseProvider from 'ui/agg_types/param_types/base';
 import AggTypesParamTypesOptionedProvider from 'ui/agg_types/param_types/optioned';
 describe('Optioned', function () {
 
-  var BaseAggParam;
-  var OptionedAggParam;
+  let BaseAggParam;
+  let OptionedAggParam;
 
   beforeEach(ngMock.module('kibana'));
   // fetch out deps

src/ui/public/agg_types/__tests__/param_types/_raw_json.js

@@ -7,11 +7,11 @@ import AggTypesParamTypesRawJsonProvider from 'ui/agg_types/param_types/raw_json
 
 module.exports = describe('JSON', function () {
   var paramName = 'json_test';
-  var BaseAggParam;
-  var JsonAggParam;
-  var aggParam;
-  var aggConfig;
-  var output;
+  let BaseAggParam;
+  let JsonAggParam;
+  let aggParam;
+  let aggConfig;
+  let output;
 
   function initAggParam(config) {
     config = config || {};

src/ui/public/agg_types/__tests__/param_types/_regex.js

@@ -7,10 +7,10 @@ import VisProvider from 'ui/vis';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 describe('Regex', function () {
 
-  var BaseAggParam;
-  var RegexAggParam;
-  var Vis;
-  var indexPattern;
+  let BaseAggParam;
+  let RegexAggParam;
+  let Vis;
+  let indexPattern;
 
   beforeEach(ngMock.module('kibana'));
   // fetch out deps
@@ -34,8 +34,8 @@ describe('Regex', function () {
   });
 
   describe('write results', function () {
-    var aggParam;
-    var aggConfig;
+    let aggParam;
+    let aggConfig;
     var output = { params: {} };
     var paramName = 'exclude';
 

src/ui/public/agg_types/__tests__/param_types/_string.js

@@ -6,11 +6,11 @@ import AggTypesParamTypesStringProvider from 'ui/agg_types/param_types/string';
 
 module.exports = describe('String', function () {
   var paramName = 'json_test';
-  var BaseAggParam;
-  var StringAggParam;
-  var aggParam;
-  var aggConfig;
-  var output;
+  let BaseAggParam;
+  let StringAggParam;
+  let aggParam;
+  let aggConfig;
+  let output;
 
   function initAggParam(config) {
     config = config || {};

src/ui/public/agg_types/buckets/create_filter/ip_range.js

@@ -2,7 +2,7 @@ import CidrMask from 'ui/utils/cidr_mask';
 import buildRangeFilter from 'ui/filter_manager/lib/range';
 export default function createIpRangeFilterProvider() {
   return function (aggConfig, key) {
-    var range;
+    let range;
     if (aggConfig.params.ipRangeType === 'mask') {
       range = new CidrMask(key).getRange();
     } else {

src/ui/public/agg_types/buckets/date_histogram.js

@@ -45,7 +45,7 @@ export default function DateHistogramAggType(timefilter, config, Private) {
     },
     createFilter: createFilter,
     decorateAggConfig: function () {
-      var buckets;
+      let buckets;
       return {
         buckets: {
           configurable: true,

src/ui/public/agg_types/param_types/raw_json.js

@@ -25,7 +25,7 @@ export default function RawJSONAggParamFactory(Private) {
    * @return {undefined}
    */
   RawJSONAggParam.prototype.write = function (aggConfig, output) {
-    var paramJSON;
+    let paramJSON;
     var param = aggConfig.params[this.name];
 
     if (!param) {

src/ui/public/bind/__tests__/bind.js

@@ -3,8 +3,8 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 describe('$scope.$bind', function () {
 
-  var $rootScope;
-  var $scope;
+  let $rootScope;
+  let $scope;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function ($injector) {

src/ui/public/binder/__tests__/binder.js

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

src/ui/public/chrome/directives/app_switcher/__tests__/app_switcher.js

@@ -12,7 +12,7 @@ import 'ui/chrome';
 import '../app_switcher';
 
 describe('appSwitcher directive', function () {
-  var env;
+  let env;
 
   beforeEach(ngMock.module('kibana'));
 

src/ui/public/compile_recursive_directive.js

@@ -26,7 +26,7 @@ uiModules
 
       // Break the recursion loop by removing the contents
       var contents = element.contents().remove();
-      var compiledContents;
+      let compiledContents;
       return {
         pre: (link && link.pre) ? link.pre : null,
         /**

src/ui/public/config/__tests__/config.js

@@ -2,9 +2,9 @@ import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import ConfigDefaultsProvider from 'ui/config/defaults';
 describe('config component', function () {
-  var $scope;
-  var config;
-  var defaults;
+  let $scope;
+  let config;
+  let defaults;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function ($injector, Private) {

src/ui/public/config/_delayed_updater.js

@@ -12,7 +12,7 @@ export default function DelayedUpdaterFactory(Private, $rootScope, Promise) {
     var updater = this;
     var queue = [];
     var log = {};
-    var timer;
+    let timer;
 
     updater.fire = function () {
       clearTimeout(timer);
@@ -21,8 +21,8 @@ export default function DelayedUpdaterFactory(Private, $rootScope, Promise) {
       if (updater.fired) return;
       updater.fired = true;
 
-      var method;
-      var body;
+      let method;
+      let body;
       var updated = [];
       var deleted = [];
 

src/ui/public/config/config.js

@@ -28,7 +28,7 @@ module.service('config', function (Private, kbnVersion, kbnIndex, $rootScope, bu
 
   // active or previous instance of DelayedUpdater. This will log and then process an
   // update once it is requested by calling #set() or #clear().
-  var updater;
+  let updater;
 
   var DocSource = Private(DocSourceProvider);
   var doc = (new DocSource())
@@ -82,7 +82,7 @@ module.service('config', function (Private, kbnVersion, kbnIndex, $rootScope, bu
   });
 
   config.get = function (key, defaultVal) {
-    var keyVal;
+    let keyVal;
 
     if (vals[key] == null) {
       if (defaultVal == null) {

src/ui/public/courier/data_source/__tests__/decorate_query.js

@@ -6,13 +6,13 @@ import DecorateQueryProvider from 'ui/courier/data_source/_decorate_query';
 
 describe('Query decorator', function () {
 
-  var config;
+  let config;
 
-  var indexPattern;
+  let indexPattern;
 
-  var getComputedFields;
+  let getComputedFields;
 
-  var fn;
+  let fn;
   beforeEach(ngMock.module(
     'kibana',
     function ($provide) {

src/ui/public/courier/data_source/__tests__/normalize_sort_request.js

@@ -5,9 +5,9 @@ import NormalizeSortRequestProvider from 'ui/courier/data_source/_normalize_sort
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
 
 describe('SearchSource#normalizeSortRequest', function () {
-  var normalizeSortRequest;
-  var indexPattern;
-  var normalizedSort;
+  let normalizeSortRequest;
+  let indexPattern;
+  let normalizedSort;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(ngMock.inject(function (Private) {

src/ui/public/courier/data_source/_doc_send_to_es.js

@@ -33,7 +33,7 @@ export default function (Promise, Private, es) {
       doc._storeVersion(resp._version);
       doc.id(resp._id);
 
-      var docFetchProm;
+      let docFetchProm;
       if (method !== 'index') {
         docFetchProm = doc.fetch();
       } else {

src/ui/public/courier/data_source/_normalize_sort_request.js

@@ -28,7 +28,7 @@ export default function normalizeSortRequest(config) {
     var indexField = indexPattern.fields.byName[sortField];
 
     if (indexField && indexField.scripted && indexField.sortable) {
-      var direction;
+      let direction;
       if (_.isString(sortValue)) direction = sortValue;
       if (_.isObject(sortValue) && sortValue.order) direction = sortValue.order;
 

src/ui/public/courier/data_source/_root_search_source.js

@@ -12,7 +12,7 @@ export default function RootSearchSource(Private, $rootScope, timefilter, Notifi
     return timefilter.get(globalSource.get('index'));
   });
 
-  var appSource; // set in setAppSource()
+  let appSource; // set in setAppSource()
   resetAppSource();
 
   // when the route changes, clear the appSource

src/ui/public/courier/saved_object/saved_object.js

@@ -151,7 +151,7 @@ export default function SavedObjectFactory(es, kbnIndex, Promise, Private, Notif
       if (!self.searchSource) return;
 
       // if we have a searchSource, set its state based on the searchSourceJSON field
-      var state;
+      let state;
       try {
         state = JSON.parse(searchSourceJson);
       } catch (e) {

src/ui/public/debounce/__tests__/debounce.js

@@ -3,9 +3,9 @@ import sinon from 'auto-release-sinon';
 import expect from 'expect.js';
 import ngMock from 'ng_mock';
 
-var debounce;
-var $timeout;
-var $timeoutSpy;
+let debounce;
+let $timeout;
+let $timeoutSpy;
 
 function init() {
   ngMock.module('kibana');
@@ -19,7 +19,7 @@ function init() {
 }
 
 describe('debounce service', function () {
-  var spy;
+  let spy;
   beforeEach(function () {
     spy = sinon.spy(function () {});
     init();

src/ui/public/debounce/debounce.js

@@ -7,10 +7,10 @@ var module = uiModules.get('kibana');
 
 module.service('debounce', ['$timeout', function ($timeout) {
   return function (func, wait, options) {
-    var timeout;
-    var args;
-    var self;
-    var result;
+    let timeout;
+    let args;
+    let self;
+    let result;
     options = _.defaults(options || {}, {
       leading: false,
       trailing: true

src/ui/public/directives/__tests__/auto_select_if_only_one.js

@@ -5,8 +5,8 @@ import ngMock from 'ng_mock';
 import 'ui/directives/auto_select_if_only_one';
 
 describe('Auto-select if only one directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var zeroOptions = [];
   var oneOption = [{label: 'foo'}];
   var multiOptions = [{label: 'foo'}, {label: 'bar'}];

src/ui/public/directives/__tests__/confirm-click.js

@@ -7,11 +7,11 @@ import 'ui/directives/confirm_click';
 import 'plugins/kibana/discover/index';
 
 
-var $parentScope;
+let $parentScope;
 
-var $scope;
+let $scope;
 
-var $elem;
+let $elem;
 
 var init = function (text) {
   // Load the application
@@ -47,7 +47,7 @@ describe('confirmClick directive', function () {
 
 
   describe('event handlers', function () {
-    var events;
+    let events;
 
     beforeEach(function () {
       init();
@@ -71,7 +71,7 @@ describe('confirmClick directive', function () {
 
 
   describe('confirmed', function () {
-    var confirmed;
+    let confirmed;
 
     beforeEach(function () {
       init();
@@ -98,7 +98,7 @@ describe('confirmClick directive', function () {
   });
 
   describe('not confirmed', function () {
-    var confirmed;
+    let confirmed;
 
     beforeEach(function () {
       init();

src/ui/public/directives/__tests__/css_truncate.js

@@ -4,11 +4,11 @@ import ngMock from 'ng_mock';
 import $ from 'jquery';
 import 'plugins/kibana/discover/index';
 
-var $parentScope;
+let $parentScope;
 
-var $scope;
+let $scope;
 
-var $elem;
+let $elem;
 
 var init = function (expandable) {
   // Load the application

src/ui/public/directives/__tests__/fixed_scroll.js

@@ -8,7 +8,7 @@ import Promise from 'bluebird';
 
 describe('FixedScroll directive', function () {
 
-  var compile;
+  let compile;
   var trash = [];
 
   beforeEach(ngMock.module('kibana'));
@@ -112,10 +112,10 @@ describe('FixedScroll directive', function () {
       { from: '$scroller', to: '$container' }
     ].forEach(function (names) {
       describe('scroll events ' + JSON.stringify(names), function () {
-        var spy;
-        var els;
-        var $from;
-        var $to;
+        let spy;
+        let els;
+        let $from;
+        let $to;
 
         beforeEach(function () {
           spy = sinon.spy($.fn, 'scrollLeft');

src/ui/public/directives/__tests__/inequality.js

@@ -4,9 +4,9 @@ import ngMock from 'ng_mock';
 import 'ui/directives/inequality';
 
 describe('greater_than model validator directive', function () {
-  var $compile;
-  var $rootScope;
-  var html;
+  let $compile;
+  let $rootScope;
+  let html;
 
   beforeEach(ngMock.module('kibana'));
 
@@ -17,7 +17,7 @@ describe('greater_than model validator directive', function () {
 
   // no value is the same as 0
   describe('without value', function () {
-    var element;
+    let element;
     beforeEach(function () {
       html = '<input type="text" ng-model="value" greater-than />';
       element = $compile(html)($rootScope);
@@ -44,7 +44,7 @@ describe('greater_than model validator directive', function () {
 
   [0, 1, 10, 42, -12].forEach(function (num) {
     describe('with value ' + num, function () {
-      var element;
+      let element;
       beforeEach(function () {
         html = '<input type="text" ng-model="value" greater-than="' + num + '" />';
         element = $compile(html)($rootScope);

src/ui/public/directives/__tests__/input_focus.js

@@ -5,13 +5,13 @@ import $ from 'jquery';
 import 'ui/directives/input_focus';
 
 describe('Input focus directive', function () {
-  var $compile;
-  var $rootScope;
-  var $timeout;
-  var element;
-  var $el;
-  var selectedEl;
-  var selectedText;
+  let $compile;
+  let $rootScope;
+  let $timeout;
+  let element;
+  let $el;
+  let selectedEl;
+  let selectedText;
   var inputValue = 'Input Text Value';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/input_whole_number.js

@@ -4,8 +4,8 @@ import ngMock from 'ng_mock';
 import 'ui/directives/input_whole_number';
 
 describe('Whole number input directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input type="text" ng-model="value" input-whole-number />';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/json_input.js

@@ -5,10 +5,10 @@ import 'ui/directives/json_input';
 
 
 describe('JSON input validation', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input ng-model="value" json-input require-keys=true />';
-  var element;
+  let element;
 
   beforeEach(ngMock.module('kibana'));
 

src/ui/public/directives/__tests__/parse_query.js

@@ -5,18 +5,18 @@ import ngMock from 'ng_mock';
 
 // Load the kibana app dependencies.
 
-var $rootScope;
-var $timeout;
-var $compile;
-var Promise;
-var Private;
-var config;
-var $elemScope;
-var $elem;
+let $rootScope;
+let $timeout;
+let $compile;
+let Promise;
+let Private;
+let config;
+let $elemScope;
+let $elem;
 
 var cycleIndex = 0;
 var markup = '<input ng-model="mockModel" parse-query input-focus type="text">';
-var fromUser;
+let fromUser;
 import toUser from 'ui/parse_query/lib/to_user';
 import 'ui/parse_query';
 import ParseQueryLibFromUserProvider from 'ui/parse_query/lib/from_user';
@@ -102,7 +102,7 @@ describe('parse-query directive', function () {
 
   describe('model presentation formatter', function () {
     it('should present undefined as empty string', function () {
-      var notDefined;
+      let notDefined;
       expect(toUser(notDefined)).to.be('');
     });
 

src/ui/public/directives/__tests__/timepicker.js

@@ -12,13 +12,13 @@ import 'plugins/kibana/discover/index';
 
 // TODO: This should not be needed, timefilter is only included here, it should move
 
-var $parentScope;
+let $parentScope;
 
-var $scope;
+let $scope;
 
-var $elem;
+let $elem;
 var anchor = '2014-01-01T06:06:06.666Z';
-var clock;
+let clock;
 
 var init = function () {
   // Load the application
@@ -85,7 +85,7 @@ describe('timepicker directive', function () {
   });
 
   describe('refresh interval', function () {
-    var $courier;
+    let $courier;
     beforeEach(function () {
       init();
       ngMock.inject(function (courier, $rootScope) {
@@ -232,7 +232,7 @@ describe('timepicker directive', function () {
     });
 
     it('disables the submit button if the form is invalid', function (done) {
-      var button;
+      let button;
       button = $elem.find('button[disabled]');
       expect(button.length).to.be(0);
 
@@ -359,7 +359,7 @@ describe('timepicker directive', function () {
 
   describe('absolute mode', function () {
 
-    var inputs;
+    let inputs;
 
     beforeEach(function () {
       init();

src/ui/public/directives/__tests__/truncate.js

@@ -5,11 +5,11 @@ import $ from 'jquery';
 import 'plugins/kibana/discover/index';
 
 
-var $parentScope;
+let $parentScope;
 
-var $scope;
+let $scope;
 
-var $elem;
+let $elem;
 
 var init = function (text) {
   // Load the application

src/ui/public/directives/__tests__/typeahead.js

@@ -9,12 +9,12 @@ import 'plugins/kibana/discover/index';
 
 var typeaheadHistoryCount = 10;
 var typeaheadName = 'unittest';
-var $parentScope;
-var $typeaheadScope;
-var $elem;
-var $typeaheadInputScope;
-var typeaheadCtrl;
-var PersistedLog;
+let $parentScope;
+let $typeaheadScope;
+let $elem;
+let $typeaheadInputScope;
+let typeaheadCtrl;
+let PersistedLog;
 
 var markup = '<div class="typeahead" kbn-typeahead="' + typeaheadName + '">' +
   '<input type="text" placeholder="Filter..." class="form-control" ng-model="query" kbn-typeahead-input>' +

src/ui/public/directives/__tests__/validate_cidr_mask.js

@@ -5,8 +5,8 @@ import 'ui/directives/validate_cidr_mask';
 
 
 describe('Validate CIDR mask directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input type="text" ng-model="value" validate-cidr-mask />';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/validate_date_math.js

@@ -5,8 +5,8 @@ import 'ui/directives/validate_date_math';
 
 
 describe('Validate date math directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input type="text" ng-model="value" validate-date-math />';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/validate_index_name.js

@@ -6,8 +6,8 @@ import 'ui/directives/validate_index_name';
 // Load the kibana app dependencies.
 
 describe('Validate index name directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input type="text" ng-model="indexName" validate-index-name />';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/validate_ip.js

@@ -5,8 +5,8 @@ import 'ui/directives/validate_ip';
 
 
 describe('Validate IP directive', function () {
-  var $compile;
-  var $rootScope;
+  let $compile;
+  let $rootScope;
   var html = '<input type="text" ng-model="value" validate-ip />';
 
   beforeEach(ngMock.module('kibana'));

src/ui/public/directives/__tests__/validate_json.js

@@ -5,9 +5,9 @@ import 'ui/directives/validate_json';
 
 // Load the kibana app dependencies.
 
-var $parentScope;
-var $elemScope;
-var $elem;
+let $parentScope;
+let $elemScope;
+let $elem;
 var mockScope = '';
 
 var input = {

src/ui/public/directives/infinite_scroll.js

@@ -10,7 +10,7 @@ module.directive('kbnInfiniteScroll', function () {
     },
     link: function ($scope, $element, attrs) {
       var $window = $(window);
-      var checkTimer;
+      let checkTimer;
 
       function onScroll() {
         if (!$scope.more) return;

src/ui/public/directives/paginate.js

@@ -106,7 +106,7 @@ uiModules.get('kibana')
         var count = perPage ? Math.ceil($scope.list.length / perPage) : 1;
 
         _.times(count, function (i) {
-          var page;
+          let page;
 
           if (perPage) {
             var start = perPage * i;

src/ui/public/directives/pretty_duration.js

@@ -23,7 +23,7 @@ module.directive('prettyDuration', function (config, quickRanges, timeUnits) {
       });
 
       function stringify() {
-        var text;
+        let text;
         // If both parts are date math, try to look up a reasonable string
         if ($scope.from && $scope.to && !moment.isMoment($scope.from) && !moment.isMoment($scope.to)) {
           var tryLookup = lookupByRange[$scope.from.toString() + ' to ' + $scope.to.toString()];

src/ui/public/directives/saved_object_finder.js

@@ -38,7 +38,7 @@ module.directive('savedObjectFinder', function ($location, $injector, kbnUrl, Pr
       var currentFilter = $scope.filter;
 
       // the most recently entered search/filter
-      var prevSearch;
+      let prevSearch;
 
       // the list of hits, used to render display
       self.hits = [];

src/ui/public/doc_table/__tests__/doc_table.js

@@ -12,16 +12,16 @@ import FixturesStubbedSearchSourceProvider from 'fixtures/stubbed_search_source'
 // Load the kibana app dependencies.
 
 
-var $parentScope;
+let $parentScope;
 
 
-var $scope;
+let $scope;
 
 
-var $timeout;
+let $timeout;
 
 
-var searchSource;
+let searchSource;
 
 var init = function ($elem, props) {
   ngMock.inject(function ($rootScope, $compile, _$timeout_) {
@@ -47,7 +47,7 @@ var destroy = function () {
 };
 
 describe('docTable', function () {
-  var $elem;
+  let $elem;
 
   beforeEach(ngMock.module('kibana'));
   beforeEach(function () {

src/ui/public/doc_table/__tests__/lib/get_sort.js

@@ -3,7 +3,7 @@ var defaultSort = {time: 'desc'};
 import expect from 'expect.js';
 import ngMock from 'ng_mock';
 import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logstash_index_pattern';
-var indexPattern;
+let indexPattern;
 
 describe('docTable', function () {
   beforeEach(ngMock.module('kibana'));

src/ui/public/doc_table/__tests__/lib/rows_headers.js

@@ -10,14 +10,14 @@ import FixturesStubbedLogstashIndexPatternProvider from 'fixtures/stubbed_logsta
 
 describe('Doc Table', function () {
 
-  var $parentScope;
+  let $parentScope;
 
-  var $scope;
+  let $scope;
 
-  var config;
+  let config;
 
   // Stub out a minimal mapping of 4 fields
-  var mapping;
+  let mapping;
 
   beforeEach(ngMock.module('kibana', 'apps/discover'));
   beforeEach(ngMock.inject(function (_config_, $rootScope, Private) {
@@ -53,7 +53,7 @@ describe('Doc Table', function () {
     });
 
     it('should be able to add and remove columns', function (done) {
-      var childElems;
+      let childElems;
       // Should include a column for toggling and the time column by default
       $parentScope.columns = ['bytes'];
       parentElem.scope().$digest();
@@ -245,7 +245,7 @@ describe('Doc Table', function () {
       });
 
       describe('expanded', function () {
-        var $details;
+        let $details;
         beforeEach(function () {
           // Open the row
           $scope.toggleRow();
@@ -278,7 +278,7 @@ describe('Doc Table', function () {
         'index-pattern="indexPattern"' +
         '></tr>'
     );
-    var $details;
+    let $details;
 
     beforeEach(function () {
       var row = getFakeRow(0, mapping);
@@ -312,10 +312,10 @@ describe('Doc Table', function () {
   });
 
   describe('row diffing', function () {
-    var $row;
-    var $scope;
-    var $root;
-    var $before;
+    let $row;
+    let $scope;
+    let $root;
+    let $before;
 
     beforeEach(ngMock.inject(function ($rootScope, $compile, Private) {
       $root = $rootScope;

src/ui/public/doc_table/components/table_row.js

@@ -46,10 +46,10 @@ module.directive('kbnTableRow', function ($compile) {
       };
 
       // when we compile the details, we use this $scope
-      var $detailsScope;
+      let $detailsScope;
 
       // when we compile the toggle button in the summary, we use this $scope
-      var $toggleScope;
+      let $toggleScope;
 
       // toggle display of the rows details, a full list of the fields from each row
       $scope.toggleRow = function () {

src/ui/public/doc_table/lib/get_sort.js

@@ -8,8 +8,8 @@ import _ from 'lodash';
  */
 function getSort(sort, indexPattern) {
   var sortObj = {};
-  var field;
-  var direction;
+  let field;
+  let direction;
 
   function isSortable(field) {
     return (indexPattern.fields.byName[field] && indexPattern.fields.byName[field].sortable);

src/ui/public/doc_title/__tests__/doc_title.js

@@ -5,11 +5,11 @@ import ngMock from 'ng_mock';
 import DocTitleProvider from 'ui/doc_title';
 
 describe('docTitle Service', function () {
-  var initialDocTitle;
+  let initialDocTitle;
   var MAIN_TITLE = 'Kibana 4';
 
-  var docTitle;
-  var $rootScope;
+  let docTitle;
+  let $rootScope;
 
   beforeEach(function () {
     initialDocTitle = document.title;
@@ -61,7 +61,7 @@ describe('docTitle Service', function () {
   });
 
   describe('#change', function () {
-    var getActiveTabStub;
+    let getActiveTabStub;
 
     beforeEach(function () {
       getActiveTabStub = sinon.stub(require('ui/chrome'), 'getActiveTab');

src/ui/public/doc_title/doc_title.js

@@ -14,7 +14,7 @@ uiModules.get('kibana')
   var baseTitle = document.title;
   var self = this;
 
-  var lastChange;
+  let lastChange;
 
   function render() {
     lastChange = lastChange || [];

src/ui/public/es.js

@@ -2,7 +2,7 @@ import 'elasticsearch-browser';
 import _ from 'lodash';
 import uiModules from 'ui/modules';
 
-var es; // share the client amoungst all apps
+let es; // share the client amoungst all apps
 uiModules
   .get('kibana', ['elasticsearch', 'kibana/config'])
   .service('es', function (esFactory, esUrl, $q, esApiVersion, esRequestTimeout) {