diff --git a/src/ui/public/Binder/Binder.js b/src/ui/public/Binder/Binder.js
index 9f5308a2210d9..568b313b0f1b0 100644
--- a/src/ui/public/Binder/Binder.js
+++ b/src/ui/public/Binder/Binder.js
@@ -1,8 +1,8 @@
-var $ = require('jquery');
-var d3 = require('d3');
-var callEach = require('lodash').callEach;
-var bindKey = require('lodash').bindKey;
-var rest = require('lodash').rest;
+let $ = require('jquery');
+let d3 = require('d3');
+let callEach = require('lodash').callEach;
+let bindKey = require('lodash').bindKey;
+let rest = require('lodash').rest;
 
 function Binder($scope) {
   this.disposal = [];
@@ -23,14 +23,14 @@ Binder.prototype.on = function (emitter/*, ...args */) {
 };
 
 Binder.prototype.jqOn = function (el/*, ...args */) {
-  var $el = $(el);
+  let $el = $(el);
   this._bind($el.on, $el.off, $el, rest(arguments));
 };
 
 Binder.prototype.fakeD3Bind = function (el, event, handler) {
   this.jqOn(el, event, function (e) {
     // mimick https://github.com/mbostock/d3/blob/3abb00113662463e5c19eb87cd33f6d0ddc23bc0/src/selection/on.js#L87-L94
-    var o = d3.event; // Events can be reentrant (e.g., focus).
+    let o = d3.event; // Events can be reentrant (e.g., focus).
     d3.event = e;
     try {
       handler.apply(this, [this.__data__]);
@@ -41,7 +41,7 @@ Binder.prototype.fakeD3Bind = function (el, event, handler) {
 };
 
 Binder.prototype.destroy = function () {
-  var destroyers = this.disposal;
+  let destroyers = this.disposal;
   this.disposal = [];
   callEach(destroyers);
 };
diff --git a/src/ui/public/agg_response/geo_json/_tooltip_formatter.js b/src/ui/public/agg_response/geo_json/_tooltip_formatter.js
index 071fc482298be..d85c4732a4744 100644
--- a/src/ui/public/agg_response/geo_json/_tooltip_formatter.js
+++ b/src/ui/public/agg_response/geo_json/_tooltip_formatter.js
@@ -1,22 +1,22 @@
 define(function (require) {
   return function TileMapTooltipFormatter($compile, $rootScope, Private) {
-    var $ = require('jquery');
-    var _ = require('lodash');
+    let $ = require('jquery');
+    let _ = require('lodash');
 
-    var fieldFormats = Private(require('ui/registry/field_formats'));
-    var $tooltipScope = $rootScope.$new();
-    var $el = $('<div>').html(require('ui/agg_response/geo_json/_tooltip.html'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
+    let $tooltipScope = $rootScope.$new();
+    let $el = $('<div>').html(require('ui/agg_response/geo_json/_tooltip.html'));
     $compile($el)($tooltipScope);
 
     return function tooltipFormatter(feature) {
       if (!feature) return '';
 
-      var value = feature.properties.value;
-      var acr = feature.properties.aggConfigResult;
-      var vis = acr.aggConfig.vis;
+      let value = feature.properties.value;
+      let acr = feature.properties.aggConfigResult;
+      let vis = acr.aggConfig.vis;
 
-      var metricAgg = acr.aggConfig;
-      var geoFormat = _.get(vis.aggs, 'byTypeName.geohash_grid[0].format');
+      let metricAgg = acr.aggConfig;
+      let geoFormat = _.get(vis.aggs, 'byTypeName.geohash_grid[0].format');
       if (!geoFormat) geoFormat = fieldFormats.getDefaultInstance('geo_point');
 
       $tooltipScope.details = [
diff --git a/src/ui/public/agg_response/geo_json/geo_json.js b/src/ui/public/agg_response/geo_json/geo_json.js
index 4b883f13820a5..7919d853e48a0 100644
--- a/src/ui/public/agg_response/geo_json/geo_json.js
+++ b/src/ui/public/agg_response/geo_json/geo_json.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function TileMapConverterFn(Private, timefilter, $compile, $rootScope) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var rowsToFeatures = require('ui/agg_response/geo_json/rowsToFeatures');
-    var tooltipFormatter = Private(require('ui/agg_response/geo_json/_tooltip_formatter'));
+    let rowsToFeatures = require('ui/agg_response/geo_json/rowsToFeatures');
+    let tooltipFormatter = Private(require('ui/agg_response/geo_json/_tooltip_formatter'));
 
     return function (vis, table) {
 
@@ -13,13 +13,13 @@ define(function (require) {
         });
       }
 
-      var geoI = columnIndex('segment');
-      var metricI = columnIndex('metric');
-      var geoAgg = _.get(table.columns, [geoI, 'aggConfig']);
-      var metricAgg = _.get(table.columns, [metricI, 'aggConfig']);
+      let geoI = columnIndex('segment');
+      let metricI = columnIndex('metric');
+      let geoAgg = _.get(table.columns, [geoI, 'aggConfig']);
+      let metricAgg = _.get(table.columns, [metricI, 'aggConfig']);
 
-      var features = rowsToFeatures(table, geoI, metricI);
-      var values = features.map(function (feature) {
+      let features = rowsToFeatures(table, geoI, metricI);
+      let values = features.map(function (feature) {
         return feature.properties.value;
       });
 
diff --git a/src/ui/public/agg_response/geo_json/rowsToFeatures.js b/src/ui/public/agg_response/geo_json/rowsToFeatures.js
index 5ce58a6ddbece..dc1bac8b141ed 100644
--- a/src/ui/public/agg_response/geo_json/rowsToFeatures.js
+++ b/src/ui/public/agg_response/geo_json/rowsToFeatures.js
@@ -1,7 +1,7 @@
 define(function (require) {
-  var decodeGeoHash = require('ui/utils/decode_geo_hash');
-  var AggConfigResult = require('ui/Vis/AggConfigResult');
-  var _ = require('lodash');
+  let decodeGeoHash = require('ui/utils/decode_geo_hash');
+  let AggConfigResult = require('ui/Vis/AggConfigResult');
+  let _ = require('lodash');
 
   function getAcr(val) {
     return val instanceof AggConfigResult ? val : null;
@@ -13,19 +13,19 @@ define(function (require) {
 
   function convertRowsToFeatures(table, geoI, metricI) {
     return _.transform(table.rows, function (features, row) {
-      var geohash = unwrap(row[geoI]);
+      let geohash = unwrap(row[geoI]);
       if (!geohash) return;
 
       // fetch latLn of northwest and southeast corners, and center point
-      var location = decodeGeoHash(geohash);
+      let location = decodeGeoHash(geohash);
 
-      var centerLatLng = [
+      let centerLatLng = [
         location.latitude[2],
         location.longitude[2]
       ];
 
       // order is nw, ne, se, sw
-      var rectangle = [
+      let rectangle = [
         [location.latitude[0], location.longitude[0]],
         [location.latitude[0], location.longitude[1]],
         [location.latitude[1], location.longitude[1]],
diff --git a/src/ui/public/agg_response/hierarchical/_array_to_linked_list.js b/src/ui/public/agg_response/hierarchical/_array_to_linked_list.js
index db419aca2c4f7..230e9cf63ac4a 100644
--- a/src/ui/public/agg_response/hierarchical/_array_to_linked_list.js
+++ b/src/ui/public/agg_response/hierarchical/_array_to_linked_list.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   return function (buckets) {
     let previous;
     _.each(buckets, function (bucket) {
diff --git a/src/ui/public/agg_response/hierarchical/_build_split.js b/src/ui/public/agg_response/hierarchical/_build_split.js
index 7c6bacc9c5f7f..6ef6ccce2bcca 100644
--- a/src/ui/public/agg_response/hierarchical/_build_split.js
+++ b/src/ui/public/agg_response/hierarchical/_build_split.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function biuldSplitProvider(Private) {
-    var transformer = Private(require('ui/agg_response/hierarchical/_transform_aggregation'));
-    var collectKeys = require('ui/agg_response/hierarchical/_collect_keys');
+    let transformer = Private(require('ui/agg_response/hierarchical/_transform_aggregation'));
+    let collectKeys = require('ui/agg_response/hierarchical/_collect_keys');
     return function (agg, metric, aggData) {
       // Ceate the split structure
-      var split = { label: '', slices: { children: [] } };
+      let split = { label: '', slices: { children: [] } };
 
       // Transform the aggData into splits
       split.slices.children = transformer(agg, metric, aggData);
diff --git a/src/ui/public/agg_response/hierarchical/_collect_branch.js b/src/ui/public/agg_response/hierarchical/_collect_branch.js
index 97370399f0e4e..5ad6518388278 100644
--- a/src/ui/public/agg_response/hierarchical/_collect_branch.js
+++ b/src/ui/public/agg_response/hierarchical/_collect_branch.js
@@ -3,13 +3,13 @@ define(function () {
     // walk up the branch for each parent
     function walk(item, memo) {
       // record the the depth
-      var depth = item.depth - 1;
+      let depth = item.depth - 1;
 
       // Using the aggConfig determine what the field name is. If the aggConfig
       // doesn't exist (which means it's an _all agg) then use the level for
       // the field name
-      var col = item.aggConfig;
-      var field = (col && col.params && col.params.field && col.params.field.displayName)
+      let col = item.aggConfig;
+      let field = (col && col.params && col.params.field && col.params.field.displayName)
         || (col && col.label)
         || ('level ' + item.depth);
 
diff --git a/src/ui/public/agg_response/hierarchical/_collect_keys.js b/src/ui/public/agg_response/hierarchical/_collect_keys.js
index 460e6c0091e2e..53e720403f9cb 100644
--- a/src/ui/public/agg_response/hierarchical/_collect_keys.js
+++ b/src/ui/public/agg_response/hierarchical/_collect_keys.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   return function collectKeys(children) {
-    var nextChildren = _.pluck(children, 'children');
-    var keys = _.pluck(children, 'name');
+    let nextChildren = _.pluck(children, 'children');
+    let keys = _.pluck(children, 'name');
     return _(nextChildren)
     .map(collectKeys)
     .flattenDeep()
diff --git a/src/ui/public/agg_response/hierarchical/_create_raw_data.js b/src/ui/public/agg_response/hierarchical/_create_raw_data.js
index 9f4346a9fca57..a10a05ee1e849 100644
--- a/src/ui/public/agg_response/hierarchical/_create_raw_data.js
+++ b/src/ui/public/agg_response/hierarchical/_create_raw_data.js
@@ -1,15 +1,15 @@
 define(function (require) {
-  var _ = require('lodash');
-  var extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
+  let _ = require('lodash');
+  let extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
   return function (vis, resp) {
 
     // Create the initial results structure
-    var results = { rows: [] };
+    let results = { rows: [] };
 
     // Create a reference to the buckets and metrics
-    var metrics = vis.aggs.bySchemaGroup.metrics;
-    var buckets = vis.aggs.bySchemaGroup.buckets;
-    var aggs = [];
+    let metrics = vis.aggs.bySchemaGroup.metrics;
+    let buckets = vis.aggs.bySchemaGroup.buckets;
+    let aggs = [];
 
     if (buckets) {
       _.each(buckets, function (bucket) {
@@ -38,7 +38,7 @@ define(function (require) {
 
     // if there are no buckets then we need to just set the value and return
     if (!buckets) {
-      var value = resp.aggregations
+      let value = resp.aggregations
         && resp.aggregations[metrics[0].id]
         && resp.aggregations[metrics[0].id].value
         || resp.hits.total;
@@ -61,9 +61,9 @@ define(function (require) {
       // iterate through all the buckets
       _.each(extractBuckets(data[agg.id], agg), function (bucket) {
 
-        var _record = _.flattenDeep([record, bucket.key]);
+        let _record = _.flattenDeep([record, bucket.key]);
         _.each(metrics, function (metric) {
-          var value = bucket.doc_count;
+          let value = bucket.doc_count;
           if (bucket[metric.id] && !_.isUndefined(bucket[metric.id].value)) {
             value = bucket[metric.id].value;
           }
@@ -74,7 +74,7 @@ define(function (require) {
         // buckets. If it does then we need to keep on walking the tree.
         // This is where the recursion happens.
         if (agg._next) {
-          var nextBucket = bucket[agg._next.id];
+          let nextBucket = bucket[agg._next.id];
           if (nextBucket && nextBucket.buckets) {
             walkBuckets(agg._next, bucket, _record);
           }
diff --git a/src/ui/public/agg_response/hierarchical/_extract_buckets.js b/src/ui/public/agg_response/hierarchical/_extract_buckets.js
index e1866ea5d0062..e5e6e7d580ff0 100644
--- a/src/ui/public/agg_response/hierarchical/_extract_buckets.js
+++ b/src/ui/public/agg_response/hierarchical/_extract_buckets.js
@@ -1,9 +1,9 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   return function (bucket, agg) {
     if (bucket && _.isPlainObject(bucket.buckets)) {
       return _.map(bucket.buckets, function (value, key) {
-        var item = _.cloneDeep(value);
+        let item = _.cloneDeep(value);
         item.key = agg ? agg.getKey(value, key) : key;
         return item;
       });
diff --git a/src/ui/public/agg_response/hierarchical/_hierarchical_tooltip_formatter.js b/src/ui/public/agg_response/hierarchical/_hierarchical_tooltip_formatter.js
index 57dd63516d70f..e6478433c387a 100644
--- a/src/ui/public/agg_response/hierarchical/_hierarchical_tooltip_formatter.js
+++ b/src/ui/public/agg_response/hierarchical/_hierarchical_tooltip_formatter.js
@@ -1,22 +1,22 @@
 define(function (require) {
   return function HierarchicalTooltipFormaterProvider($rootScope, $compile, $sce) {
-    var _ = require('lodash');
-    var $ = require('jquery');
-    var $tooltip = $(require('ui/agg_response/hierarchical/_tooltip.html'));
-    var collectBranch = require('ui/agg_response/hierarchical/_collect_branch');
-    var $tooltipScope = $rootScope.$new();
-    var numeral = require('numeral');
+    let _ = require('lodash');
+    let $ = require('jquery');
+    let $tooltip = $(require('ui/agg_response/hierarchical/_tooltip.html'));
+    let collectBranch = require('ui/agg_response/hierarchical/_collect_branch');
+    let $tooltipScope = $rootScope.$new();
+    let numeral = require('numeral');
 
     $compile($tooltip)($tooltipScope);
 
     return function (columns) {
       return function (event) {
-        var datum = event.datum;
+        let datum = event.datum;
 
         // Collect the current leaf and parents into an array of values
         $tooltipScope.rows = collectBranch(datum);
 
-        var metricCol = $tooltipScope.metricCol = _.find(columns, { categoryName: 'metric' });
+        let metricCol = $tooltipScope.metricCol = _.find(columns, { categoryName: 'metric' });
 
         // Map those values to what the tooltipSource.rows format.
         _.forEachRight($tooltipScope.rows, function (row, i, rows) {
diff --git a/src/ui/public/agg_response/hierarchical/_transform_aggregation.js b/src/ui/public/agg_response/hierarchical/_transform_aggregation.js
index 0a3342ce8d23f..b45eebe7a7f51 100644
--- a/src/ui/public/agg_response/hierarchical/_transform_aggregation.js
+++ b/src/ui/public/agg_response/hierarchical/_transform_aggregation.js
@@ -1,18 +1,18 @@
 define(function (require) {
-  var _ = require('lodash');
-  var extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
+  let _ = require('lodash');
+  let extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
   return function transformAggregationProvider(Private) {
-    var AggConfigResult = require('ui/Vis/AggConfigResult');
+    let AggConfigResult = require('ui/Vis/AggConfigResult');
     return function transformAggregation(agg, metric, aggData, parent) {
       return _.map(extractBuckets(aggData, agg), function (bucket) {
-        var aggConfigResult = new AggConfigResult(
+        let aggConfigResult = new AggConfigResult(
           agg,
           parent && parent.aggConfigResult,
           metric.getValue(bucket),
           agg.getKey(bucket)
         );
 
-        var branch = {
+        let branch = {
           name: agg.fieldFormatter()(bucket.key),
           size: aggConfigResult.value,
           aggConfig: agg,
@@ -28,7 +28,7 @@ define(function (require) {
         // If the next bucket exists and it has children the we need to
         // transform it as well. This is where the recursion happens.
         if (agg._next) {
-          var nextBucket = bucket[agg._next.id];
+          let nextBucket = bucket[agg._next.id];
           if (nextBucket && nextBucket.buckets) {
             branch.children = transformAggregation(agg._next, metric, nextBucket, branch);
           }
diff --git a/src/ui/public/agg_response/hierarchical/build_hierarchical_data.js b/src/ui/public/agg_response/hierarchical/build_hierarchical_data.js
index 31ca1ca4b0b69..815335cf6e3f6 100644
--- a/src/ui/public/agg_response/hierarchical/build_hierarchical_data.js
+++ b/src/ui/public/agg_response/hierarchical/build_hierarchical_data.js
@@ -1,38 +1,38 @@
 define(function (require) {
   return function buildHierarchicalDataProvider(Private, Notifier) {
-    var _ = require('lodash');
-    var buildSplit = Private(require('ui/agg_response/hierarchical/_build_split'));
-    var extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
-    var createRawData = require('ui/agg_response/hierarchical/_create_raw_data');
-    var arrayToLinkedList = require('ui/agg_response/hierarchical/_array_to_linked_list');
-    var tooltipFormatter = Private(require('ui/agg_response/hierarchical/_hierarchical_tooltip_formatter'));
+    let _ = require('lodash');
+    let buildSplit = Private(require('ui/agg_response/hierarchical/_build_split'));
+    let extractBuckets = require('ui/agg_response/hierarchical/_extract_buckets');
+    let createRawData = require('ui/agg_response/hierarchical/_create_raw_data');
+    let arrayToLinkedList = require('ui/agg_response/hierarchical/_array_to_linked_list');
+    let tooltipFormatter = Private(require('ui/agg_response/hierarchical/_hierarchical_tooltip_formatter'));
 
-    var AggConfigResult = require('ui/Vis/AggConfigResult');
+    let AggConfigResult = require('ui/Vis/AggConfigResult');
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Pie chart response converter'
     });
 
     return function (vis, resp) {
       // Create a refrenece to the buckets
-      var buckets = vis.aggs.bySchemaGroup.buckets;
+      let buckets = vis.aggs.bySchemaGroup.buckets;
 
 
       // Find the metric so it's easier to reference.
       // TODO: Change this to support multiple metrics.
-      var metric = vis.aggs.bySchemaGroup.metrics[0];
+      let metric = vis.aggs.bySchemaGroup.metrics[0];
 
       // Link each agg to the next agg. This will be
       // to identify the next bucket aggregation
       buckets = arrayToLinkedList(buckets);
 
       // Create the raw data to be used in the spy panel
-      var raw = createRawData(vis, resp);
+      let raw = createRawData(vis, resp);
 
       // If buckets is falsy then we should just return the aggs
       if (!buckets) {
-        var label = 'Count';
-        var value = resp.aggregations
+        let label = 'Count';
+        let value = resp.aggregations
           && resp.aggregations[metric.id]
           && resp.aggregations[metric.id].value
           || resp.hits.total;
@@ -49,8 +49,8 @@ define(function (require) {
         };
       }
 
-      var firstAgg = buckets[0];
-      var aggData = resp.aggregations[firstAgg.id];
+      let firstAgg = buckets[0];
+      let aggData = resp.aggregations[firstAgg.id];
 
       if (!firstAgg._next && firstAgg.schema.name === 'split') {
         notify.error('Splitting charts without splitting slices is not supported. Pretending that we are just splitting slices.');
@@ -58,7 +58,7 @@ define(function (require) {
 
       // start with splitting slices
       if (!firstAgg._next || firstAgg.schema.name === 'segment') {
-        var split = buildSplit(firstAgg, metric, aggData);
+        let split = buildSplit(firstAgg, metric, aggData);
         split.hits = resp.hits.total;
         split.raw = raw;
         split.tooltipFormatter = tooltipFormatter(raw.columns);
@@ -66,17 +66,17 @@ define(function (require) {
       }
 
       // map the split aggregations into rows.
-      var rows = _.map(extractBuckets(aggData, firstAgg), function (bucket) {
-        var agg = firstAgg._next;
-        var split = buildSplit(agg, metric, bucket[agg.id]);
+      let rows = _.map(extractBuckets(aggData, firstAgg), function (bucket) {
+        let agg = firstAgg._next;
+        let split = buildSplit(agg, metric, bucket[agg.id]);
         // Since splits display labels we need to set it.
         split.label = firstAgg.fieldFormatter()(agg.getKey(bucket));
 
-        var displayName = firstAgg.fieldDisplayName();
+        let displayName = firstAgg.fieldDisplayName();
         if (!_.isEmpty(displayName)) split.label += ': ' + displayName;
 
         split.tooltipFormatter = tooltipFormatter(raw.columns);
-        var aggConfigResult = new AggConfigResult(firstAgg, null, null, firstAgg.getKey(bucket));
+        let aggConfigResult = new AggConfigResult(firstAgg, null, null, firstAgg.getKey(bucket));
         split.split = { aggConfig: firstAgg, aggConfigResult: aggConfigResult, key: bucket.key };
         _.each(split.slices.children, function (child) {
           child.aggConfigResult.$parent = aggConfigResult;
@@ -84,7 +84,7 @@ define(function (require) {
         return split;
       });
 
-      var result = { hits: resp.hits.total, raw: raw };
+      let result = { hits: resp.hits.total, raw: raw };
       if (firstAgg.params.row) {
         result.rows = rows;
       } else {
diff --git a/src/ui/public/agg_response/point_series/_fake_x_aspect.js b/src/ui/public/agg_response/point_series/_fake_x_aspect.js
index 5de2c4928aff9..32094060195c1 100644
--- a/src/ui/public/agg_response/point_series/_fake_x_aspect.js
+++ b/src/ui/public/agg_response/point_series/_fake_x_aspect.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function PointSeriesFakeXAxis(Private) {
-    var AggConfig = Private(require('ui/Vis/AggConfig'));
-    var AggType = Private(require('ui/agg_types/AggType'));
+    let AggConfig = Private(require('ui/Vis/AggConfig'));
+    let AggType = Private(require('ui/agg_types/AggType'));
 
-    var allAgg = new AggType({
+    let allAgg = new AggType({
       name: 'all',
       title: 'All docs',
       ordered: false,
@@ -11,7 +11,7 @@ define(function (require) {
     });
 
     return function makeFakeXAxis(vis) {
-      var fake = new AggConfig(vis, {
+      let fake = new AggConfig(vis, {
         type: allAgg,
         schema: vis.type.schemas.all.byName.segment
       });
diff --git a/src/ui/public/agg_response/point_series/_get_aspects.js b/src/ui/public/agg_response/point_series/_get_aspects.js
index 58ce78b3549ef..ff86b41ee317a 100644
--- a/src/ui/public/agg_response/point_series/_get_aspects.js
+++ b/src/ui/public/agg_response/point_series/_get_aspects.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function PointSeriesGetAspects(Private) {
-    var _ = require('lodash');
-    var fakeXAspect = Private(require('ui/agg_response/point_series/_fake_x_aspect'));
+    let _ = require('lodash');
+    let fakeXAspect = Private(require('ui/agg_response/point_series/_fake_x_aspect'));
 
-    var map = {
+    let map = {
       segment: 'x',
       metric: 'y',
       radius: 'z',
@@ -12,12 +12,12 @@ define(function (require) {
     };
 
     function columnToAspect(aspects, col, i) {
-      var schema = col.aggConfig.schema.name;
+      let schema = col.aggConfig.schema.name;
 
-      var name = map[schema];
+      let name = map[schema];
       if (!name) throw new TypeError('unknown schema name "' + schema + '"');
 
-      var aspect = {
+      let aspect = {
         i: i,
         col: col,
         agg: col.aggConfig
@@ -36,7 +36,7 @@ define(function (require) {
      *                    may be undefined, a single aspect, or an array of aspects.
      */
     return function getAspects(vis, table) {
-      var aspects = _(table.columns)
+      let aspects = _(table.columns)
       // write each column into the aspects under it's group
       .transform(columnToAspect, {})
       // unwrap groups that only have one value, and validate groups that have more
diff --git a/src/ui/public/agg_response/point_series/_get_point.js b/src/ui/public/agg_response/point_series/_get_point.js
index c0b4e30ef2f0c..105d4675c0f25 100644
--- a/src/ui/public/agg_response/point_series/_get_point.js
+++ b/src/ui/public/agg_response/point_series/_get_point.js
@@ -1,15 +1,15 @@
 define(function (require) {
   return function PointSeriesGetPoint() {
-    var _ = require('lodash');
+    let _ = require('lodash');
     function unwrap(aggConfigResult, def) {
       return aggConfigResult ? aggConfigResult.value : def;
     }
 
     return function getPoint(x, series, yScale, row, y, z) {
-      var zRow = z && row[z.i];
-      var xRow = row[x.i];
+      let zRow = z && row[z.i];
+      let xRow = row[x.i];
 
-      var point = {
+      let point = {
         x: unwrap(xRow, '_all'),
         xi: xRow && xRow.$order,
         y: unwrap(row[y.i]),
diff --git a/src/ui/public/agg_response/point_series/_get_series.js b/src/ui/public/agg_response/point_series/_get_series.js
index 60b6cf5992786..331c1531a6448 100644
--- a/src/ui/public/agg_response/point_series/_get_series.js
+++ b/src/ui/public/agg_response/point_series/_get_series.js
@@ -1,30 +1,30 @@
 define(function (require) {
   return function PointSeriesGetSeries(Private) {
-    var _ = require('lodash');
-    var getPoint = Private(require('ui/agg_response/point_series/_get_point'));
-    var addToSiri = Private(require('ui/agg_response/point_series/_add_to_siri'));
+    let _ = require('lodash');
+    let getPoint = Private(require('ui/agg_response/point_series/_get_point'));
+    let addToSiri = Private(require('ui/agg_response/point_series/_add_to_siri'));
 
     return function getSeries(rows, chart) {
-      var aspects = chart.aspects;
-      var multiY = _.isArray(aspects.y);
-      var yScale = chart.yScale;
-      var partGetPoint = _.partial(getPoint, aspects.x, aspects.series, yScale);
+      let aspects = chart.aspects;
+      let multiY = _.isArray(aspects.y);
+      let yScale = chart.yScale;
+      let partGetPoint = _.partial(getPoint, aspects.x, aspects.series, yScale);
 
-      var series = _(rows)
+      let series = _(rows)
       .transform(function (series, row) {
         if (!multiY) {
-          var point = partGetPoint(row, aspects.y, aspects.z);
+          let point = partGetPoint(row, aspects.y, aspects.z);
           if (point) addToSiri(series, point, point.series);
           return;
         }
 
         aspects.y.forEach(function (y) {
-          var point = partGetPoint(row, y, aspects.z);
+          let point = partGetPoint(row, y, aspects.z);
           if (!point) return;
 
-          var prefix = point.series ? point.series + ': ' : '';
-          var seriesId = prefix + y.agg.id;
-          var seriesLabel = prefix + y.col.title;
+          let prefix = point.series ? point.series + ': ' : '';
+          let seriesId = prefix + y.agg.id;
+          let seriesLabel = prefix + y.col.title;
 
           addToSiri(series, point, seriesId, seriesLabel);
         });
@@ -35,11 +35,11 @@ define(function (require) {
 
       if (multiY) {
         series = _.sortBy(series, function (siri) {
-          var firstVal = siri.values[0];
+          let firstVal = siri.values[0];
           let y;
 
           if (firstVal) {
-            var agg = firstVal.aggConfigResult.aggConfig;
+            let agg = firstVal.aggConfigResult.aggConfig;
             y = _.find(aspects.y, function (y) {
               return y.agg === agg;
             });
diff --git a/src/ui/public/agg_response/point_series/_init_x_axis.js b/src/ui/public/agg_response/point_series/_init_x_axis.js
index 3910621f701c5..2a3584c3834f7 100644
--- a/src/ui/public/agg_response/point_series/_init_x_axis.js
+++ b/src/ui/public/agg_response/point_series/_init_x_axis.js
@@ -1,14 +1,14 @@
 define(function () {
   return function PointSeriesInitX() {
     return function initXAxis(chart) {
-      var x = chart.aspects.x;
+      let x = chart.aspects.x;
       chart.xAxisFormatter = x.agg ? x.agg.fieldFormatter() : String;
       chart.xAxisLabel = x.col.title;
 
       if (!x.agg || !x.agg.type.ordered) return;
 
       chart.ordered = {};
-      var xAggOutput = x.agg.write();
+      let xAggOutput = x.agg.write();
       if (xAggOutput.params.interval) {
         chart.ordered.interval = xAggOutput.params.interval;
       }
diff --git a/src/ui/public/agg_response/point_series/_init_y_axis.js b/src/ui/public/agg_response/point_series/_init_y_axis.js
index b47ec2ef884c2..a34039073e75f 100644
--- a/src/ui/public/agg_response/point_series/_init_y_axis.js
+++ b/src/ui/public/agg_response/point_series/_init_y_axis.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function PointSeriesInitYAxis() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     return function initYAxis(chart) {
-      var y = chart.aspects.y;
-      var x = chart.aspects.x;
+      let y = chart.aspects.y;
+      let x = chart.aspects.x;
 
       if (_.isArray(y)) {
         // TODO: vis option should allow choosing this format
@@ -15,7 +15,7 @@ define(function (require) {
         chart.yAxisLabel = y.col.title;
       }
 
-      var xAggOutput = x.agg.write();
+      let xAggOutput = x.agg.write();
       chart.yScale = xAggOutput.metricScale || null;
     };
   };
diff --git a/src/ui/public/agg_response/point_series/_ordered_date_axis.js b/src/ui/public/agg_response/point_series/_ordered_date_axis.js
index 805bea1c43bbe..34662a7f1f94c 100644
--- a/src/ui/public/agg_response/point_series/_ordered_date_axis.js
+++ b/src/ui/public/agg_response/point_series/_ordered_date_axis.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function PointSeriesOrderedDateAxis(timefilter) {
-    var moment = require('moment');
+    let moment = require('moment');
 
     return function orderedDateAxis(vis, chart) {
-      var xAgg = chart.aspects.x.agg;
-      var buckets = xAgg.buckets;
-      var format = buckets.getScaledDateFormat();
+      let xAgg = chart.aspects.x.agg;
+      let buckets = xAgg.buckets;
+      let format = buckets.getScaledDateFormat();
 
       chart.xAxisFormatter = function (val) {
         return moment(val).format(format);
@@ -16,8 +16,8 @@ define(function (require) {
         interval: buckets.getInterval(),
       };
 
-      var axisOnTimeField = xAgg.fieldIsTimeField();
-      var bounds = buckets.getBounds();
+      let axisOnTimeField = xAgg.fieldIsTimeField();
+      let bounds = buckets.getBounds();
       if (bounds && axisOnTimeField) {
         chart.ordered.min = bounds.min;
         chart.ordered.max = bounds.max;
diff --git a/src/ui/public/agg_response/point_series/_tooltip_formatter.js b/src/ui/public/agg_response/point_series/_tooltip_formatter.js
index 97345117543a3..edd245ab99d50 100644
--- a/src/ui/public/agg_response/point_series/_tooltip_formatter.js
+++ b/src/ui/public/agg_response/point_series/_tooltip_formatter.js
@@ -1,23 +1,23 @@
 define(function (require) {
   return function PointSeriesTooltipFormatter($compile, $rootScope) {
-    var $ = require('jquery');
+    let $ = require('jquery');
 
-    var $tooltipScope = $rootScope.$new();
-    var $tooltip = $(require('ui/agg_response/point_series/_tooltip.html'));
+    let $tooltipScope = $rootScope.$new();
+    let $tooltip = $(require('ui/agg_response/point_series/_tooltip.html'));
     $compile($tooltip)($tooltipScope);
 
     return function tooltipFormatter(event) {
-      var datum = event.datum;
+      let datum = event.datum;
       if (!datum || !datum.aggConfigResult) return '';
 
-      var details = $tooltipScope.details = [];
-      var result = { $parent: datum.aggConfigResult };
+      let details = $tooltipScope.details = [];
+      let result = { $parent: datum.aggConfigResult };
 
       function addDetail(result) {
-        var agg = result.aggConfig;
-        var value = result.value;
+        let agg = result.aggConfig;
+        let value = result.value;
 
-        var detail = {
+        let detail = {
           value: agg.fieldFormatter()(value),
           label: agg.makeLabel()
         };
diff --git a/src/ui/public/agg_response/point_series/point_series.js b/src/ui/public/agg_response/point_series/point_series.js
index ddaf2c9beef21..1bdc88764b77b 100644
--- a/src/ui/public/agg_response/point_series/point_series.js
+++ b/src/ui/public/agg_response/point_series/point_series.js
@@ -1,24 +1,24 @@
 define(function (require) {
   return function PointSeriesProvider(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var getSeries = Private(require('ui/agg_response/point_series/_get_series'));
-    var getAspects = Private(require('ui/agg_response/point_series/_get_aspects'));
-    var initYAxis = Private(require('ui/agg_response/point_series/_init_y_axis'));
-    var initXAxis = Private(require('ui/agg_response/point_series/_init_x_axis'));
-    var setupOrderedDateXAxis = Private(require('ui/agg_response/point_series/_ordered_date_axis'));
-    var tooltipFormatter = Private(require('ui/agg_response/point_series/_tooltip_formatter'));
+    let getSeries = Private(require('ui/agg_response/point_series/_get_series'));
+    let getAspects = Private(require('ui/agg_response/point_series/_get_aspects'));
+    let initYAxis = Private(require('ui/agg_response/point_series/_init_y_axis'));
+    let initXAxis = Private(require('ui/agg_response/point_series/_init_x_axis'));
+    let setupOrderedDateXAxis = Private(require('ui/agg_response/point_series/_ordered_date_axis'));
+    let tooltipFormatter = Private(require('ui/agg_response/point_series/_tooltip_formatter'));
 
     return function pointSeriesChartDataFromTable(vis, table) {
-      var chart = {};
-      var aspects = chart.aspects = getAspects(vis, table);
+      let chart = {};
+      let aspects = chart.aspects = getAspects(vis, table);
 
       chart.tooltipFormatter = tooltipFormatter;
 
       initXAxis(chart);
       initYAxis(chart);
 
-      var datedX = aspects.x.agg.type.ordered && aspects.x.agg.type.ordered.date;
+      let datedX = aspects.x.agg.type.ordered && aspects.x.agg.type.ordered.date;
       if (datedX) {
         setupOrderedDateXAxis(vis, chart);
       }
diff --git a/src/ui/public/agg_response/tabify/_buckets.js b/src/ui/public/agg_response/tabify/_buckets.js
index 6fc08cd41e75f..40c9ed62913d3 100644
--- a/src/ui/public/agg_response/tabify/_buckets.js
+++ b/src/ui/public/agg_response/tabify/_buckets.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function AggResponseBucketsProvider() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     function Buckets(aggResp) {
       aggResp = aggResp || false;
@@ -16,7 +16,7 @@ define(function (require) {
     }
 
     Buckets.prototype.forEach = function (fn) {
-      var buckets = this.buckets;
+      let buckets = this.buckets;
 
       if (this.objectMode) {
         this._keys.forEach(function (key) {
diff --git a/src/ui/public/agg_response/tabify/_get_columns.js b/src/ui/public/agg_response/tabify/_get_columns.js
index e652cf0f61e02..13a3ad8a64b90 100644
--- a/src/ui/public/agg_response/tabify/_get_columns.js
+++ b/src/ui/public/agg_response/tabify/_get_columns.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function GetColumnsProvider(Private) {
-    var _ = require('lodash');
-    var AggConfig = Private(require('ui/Vis/AggConfig'));
+    let _ = require('lodash');
+    let AggConfig = Private(require('ui/Vis/AggConfig'));
 
     return function getColumns(vis, minimal) {
-      var aggs = vis.aggs.getResponseAggs();
+      let aggs = vis.aggs.getResponseAggs();
 
       if (minimal == null) minimal = !vis.isHierarchical();
 
@@ -23,10 +23,10 @@ define(function (require) {
       }
 
       // supposed to be bucket,...metrics,bucket,...metrics
-      var columns = [];
+      let columns = [];
 
       // seperate the metrics
-      var grouped = _.groupBy(aggs, function (agg) {
+      let grouped = _.groupBy(aggs, function (agg) {
         return agg.schema.group;
       });
 
diff --git a/src/ui/public/agg_response/tabify/_response_writer.js b/src/ui/public/agg_response/tabify/_response_writer.js
index f6da52f7b4229..a4f4f6f475281 100644
--- a/src/ui/public/agg_response/tabify/_response_writer.js
+++ b/src/ui/public/agg_response/tabify/_response_writer.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function TabbedAggResponseWriterProvider(Private) {
-    var _ = require('lodash');
-    var Table = Private(require('ui/agg_response/tabify/_table'));
-    var TableGroup = Private(require('ui/agg_response/tabify/_table_group'));
-    var getColumns = Private(require('ui/agg_response/tabify/_get_columns'));
+    let _ = require('lodash');
+    let Table = Private(require('ui/agg_response/tabify/_table'));
+    let TableGroup = Private(require('ui/agg_response/tabify/_table_group'));
+    let getColumns = Private(require('ui/agg_response/tabify/_get_columns'));
 
-    var AggConfigResult = require('ui/Vis/AggConfigResult');
+    let AggConfigResult = require('ui/Vis/AggConfigResult');
 
     _.class(SplitAcr).inherits(AggConfigResult);
     function SplitAcr(agg, parent, key) {
@@ -23,7 +23,7 @@ define(function (require) {
       this.opts = opts || {};
       this.rowBuffer = [];
 
-      var visIsHier = vis.isHierarchical();
+      let visIsHier = vis.isHierarchical();
 
       // do the options allow for splitting? we will only split if true and
       // tabify calls the split method.
@@ -65,9 +65,9 @@ define(function (require) {
      * @return {Table/TableGroup} table - the created table
      */
     TabbedAggResponseWriter.prototype._table = function (group, agg, key) {
-      var Class = (group) ? TableGroup : Table;
-      var table = new Class();
-      var parent = this.splitStack[0];
+      let Class = (group) ? TableGroup : Table;
+      let table = new Class();
+      let parent = this.splitStack[0];
 
       if (group) {
         table.aggConfig = agg;
@@ -93,7 +93,7 @@ define(function (require) {
      * @param  {function} block - a function to execute for each sub bucket
      */
     TabbedAggResponseWriter.prototype.split = function (agg, buckets, block) {
-      var self = this;
+      let self = this;
 
       if (!self.canSplit) {
         throw new Error('attempted to split when splitting is disabled');
@@ -103,11 +103,11 @@ define(function (require) {
 
       buckets.forEach(function (bucket, key) {
         // find the existing split that we should extend
-        var tableGroup = _.find(self.splitStack[0].tables, { aggConfig: agg, key: key });
+        let tableGroup = _.find(self.splitStack[0].tables, { aggConfig: agg, key: key });
         // create the split if it doesn't exist yet
         if (!tableGroup) tableGroup = self._table(true, agg, key);
 
-        var splitAcr = false;
+        let splitAcr = false;
         if (self.asAggConfigResults) {
           splitAcr = self._injectParentSplit(agg, key);
         }
@@ -125,7 +125,7 @@ define(function (require) {
     };
 
     TabbedAggResponseWriter.prototype._removeAggFromColumns = function (agg) {
-      var i = _.findIndex(this.columns, function (col) {
+      let i = _.findIndex(this.columns, function (col) {
         return col.aggConfig === agg;
       });
 
@@ -138,8 +138,8 @@ define(function (require) {
 
       // hierarchical vis creats additional columns for each bucket
       // we will remove those too
-      var mCol = this.columns.splice(i, 1).pop();
-      var mI = _.findIndex(this.aggStack, function (agg) {
+      let mCol = this.columns.splice(i, 1).pop();
+      let mI = _.findIndex(this.aggStack, function (agg) {
         return agg === mCol.aggConfig;
       });
 
@@ -158,12 +158,12 @@ define(function (require) {
      * @return {SplitAcr} - the AggConfigResult created for the split bucket
      */
     TabbedAggResponseWriter.prototype._injectParentSplit = function (agg, key) {
-      var oldList = this.acrStack;
-      var newList = this.acrStack = [];
+      let oldList = this.acrStack;
+      let newList = this.acrStack = [];
 
       // walk from right to left through the old stack
       // and move things to the new stack
-      var injected = false;
+      let injected = false;
 
       if (!oldList.length) {
         injected = new SplitAcr(agg, null, key);
@@ -173,7 +173,7 @@ define(function (require) {
 
       // walk from right to left, emptying the previous list
       while (oldList.length) {
-        var acr = oldList.pop();
+        let acr = oldList.pop();
 
         // ignore other splits
         if (acr instanceof SplitAcr) {
@@ -187,11 +187,11 @@ define(function (require) {
           newList.unshift(injected);
         }
 
-        var newAcr = new AggConfigResult(acr.aggConfig, newList[0], acr.value, acr.aggConfig.getKey(acr));
+        let newAcr = new AggConfigResult(acr.aggConfig, newList[0], acr.value, acr.aggConfig.getKey(acr));
         newList.unshift(newAcr);
 
         // and replace the acr in the row buffer if its there
-        var rowI = this.rowBuffer.indexOf(acr);
+        let rowI = this.rowBuffer.indexOf(acr);
         if (rowI > -1) {
           this.rowBuffer[rowI] = newAcr;
         }
@@ -213,7 +213,7 @@ define(function (require) {
         value = new AggConfigResult(agg, this.acrStack[0], value, value);
       }
 
-      var staskResult = this.asAggConfigResults && value.type === 'bucket';
+      let staskResult = this.asAggConfigResults && value.type === 'bucket';
 
       this.rowBuffer.push(value);
       if (staskResult) this.acrStack.unshift(value);
@@ -235,14 +235,14 @@ define(function (require) {
      * @return {undefined}
      */
     TabbedAggResponseWriter.prototype.row = function (buffer) {
-      var cells = buffer || this.rowBuffer.slice(0);
+      let cells = buffer || this.rowBuffer.slice(0);
 
       if (!this.partialRows && cells.length < this.columns.length) {
         return;
       }
 
-      var split = this.splitStack[0];
-      var table = split.tables[0] || this._table(false);
+      let split = this.splitStack[0];
+      let table = split.tables[0] || this._table(false);
 
       while (cells.length < this.columns.length) cells.push('');
       table.rows.push(cells);
@@ -255,7 +255,7 @@ define(function (require) {
      * @return {object} - the final table-tree
      */
     TabbedAggResponseWriter.prototype.response = function () {
-      var columns = this.columns;
+      let columns = this.columns;
 
       // give the columns some metadata
       columns.map(function (col) {
@@ -270,7 +270,7 @@ define(function (require) {
 
       if (this.canSplit) return this.root;
 
-      var table = this.root.tables[0];
+      let table = this.root.tables[0];
       if (!table) return;
 
       delete table.$parent;
diff --git a/src/ui/public/agg_response/tabify/_table.js b/src/ui/public/agg_response/tabify/_table.js
index 855a72a6b4df2..ce8c800d984cf 100644
--- a/src/ui/public/agg_response/tabify/_table.js
+++ b/src/ui/public/agg_response/tabify/_table.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function TableProvider() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     /**
      * Simple table class that is used to contain the rows and columns that create
diff --git a/src/ui/public/agg_response/tabify/_table_group.js b/src/ui/public/agg_response/tabify/_table_group.js
index 28830e82493ba..9512d07b50b96 100644
--- a/src/ui/public/agg_response/tabify/_table_group.js
+++ b/src/ui/public/agg_response/tabify/_table_group.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function TableGroupProvider() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     /**
      * Simple object that wraps multiple tables. It contains information about the aggConfig
diff --git a/src/ui/public/agg_response/tabify/tabify.js b/src/ui/public/agg_response/tabify/tabify.js
index 4caa8ee92a93d..68e78d06b6736 100644
--- a/src/ui/public/agg_response/tabify/tabify.js
+++ b/src/ui/public/agg_response/tabify/tabify.js
@@ -1,16 +1,16 @@
 define(function (require) {
   return function tabifyAggResponseProvider(Private, Notifier) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var AggConfig = Private(require('ui/Vis/AggConfig'));
-    var TabbedAggResponseWriter = Private(require('ui/agg_response/tabify/_response_writer'));
-    var Buckets = Private(require('ui/agg_response/tabify/_buckets'));
-    var notify = new Notifier({ location: 'agg_response/tabify'});
+    let AggConfig = Private(require('ui/Vis/AggConfig'));
+    let TabbedAggResponseWriter = Private(require('ui/agg_response/tabify/_response_writer'));
+    let Buckets = Private(require('ui/agg_response/tabify/_buckets'));
+    let notify = new Notifier({ location: 'agg_response/tabify'});
 
     function tabifyAggResponse(vis, esResponse, respOpts) {
-      var write = new TabbedAggResponseWriter(vis, respOpts);
+      let write = new TabbedAggResponseWriter(vis, respOpts);
 
-      var topLevelBucket = _.assign({}, esResponse.aggregations, {
+      let topLevelBucket = _.assign({}, esResponse.aggregations, {
         doc_count: esResponse.hits.total
       });
 
@@ -29,13 +29,13 @@ define(function (require) {
      * @returns {undefined}
      */
     function collectBucket(write, bucket, key) {
-      var agg = write.aggStack.shift();
+      let agg = write.aggStack.shift();
 
       switch (agg.schema.group) {
         case 'buckets':
-          var buckets = new Buckets(bucket[agg.id]);
+          let buckets = new Buckets(bucket[agg.id]);
           if (buckets.length) {
-            var splitting = write.canSplit && agg.schema.name === 'split';
+            let splitting = write.canSplit && agg.schema.name === 'split';
             if (splitting) {
               write.split(agg, buckets, function forEachBucket(subBucket, key) {
                 collectBucket(write, subBucket, agg.getKey(subBucket), key);
@@ -61,7 +61,7 @@ define(function (require) {
           }
           break;
         case 'metrics':
-          var value = agg.getValue(bucket);
+          let value = agg.getValue(bucket);
           write.cell(agg, value, function () {
             if (!write.aggStack.length) {
               // row complete
@@ -80,7 +80,7 @@ define(function (require) {
     // write empty values for each bucket agg, then write
     // the metrics from the initial bucket using collectBucket()
     function passEmptyBuckets(write, bucket, key) {
-      var agg = write.aggStack.shift();
+      let agg = write.aggStack.shift();
 
       switch (agg.schema.group) {
         case 'metrics':
diff --git a/src/ui/public/agg_table/agg_table.js b/src/ui/public/agg_table/agg_table.js
index 2b6fe0cceccde..910dde46a5c0b 100644
--- a/src/ui/public/agg_table/agg_table.js
+++ b/src/ui/public/agg_table/agg_table.js
@@ -6,7 +6,7 @@ define(function (require) {
   require('ui/modules')
   .get('kibana')
   .directive('kbnAggTable', function ($filter, config, Private, compileRecursiveDirective) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     return {
       restrict: 'E',
@@ -23,7 +23,7 @@ define(function (require) {
         return compileRecursiveDirective.compile($el);
       },
       controller: function ($scope) {
-        var self = this;
+        let self = this;
 
         self.sort = null;
         self._saveAs = require('@spalger/filesaver').saveAs;
@@ -33,15 +33,15 @@ define(function (require) {
         };
 
         self.exportAsCsv = function (formatted) {
-          var csv = new Blob([self.toCsv(formatted)], { type: 'text/plain' });
+          let csv = new Blob([self.toCsv(formatted)], { type: 'text/plain' });
           self._saveAs(csv, self.csv.filename);
         };
 
         self.toCsv = function (formatted) {
-          var rows = $scope.table.rows;
-          var columns = formatted ? $scope.formattedColumns : $scope.table.columns;
-          var nonAlphaNumRE = /[^a-zA-Z0-9]/;
-          var allDoubleQuoteRE = /"/g;
+          let rows = $scope.table.rows;
+          let columns = formatted ? $scope.formattedColumns : $scope.table.columns;
+          let nonAlphaNumRE = /[^a-zA-Z0-9]/;
+          let allDoubleQuoteRE = /"/g;
 
           function escape(val) {
             if (!formatted && _.isObject(val)) val = val.valueOf();
@@ -53,7 +53,7 @@ define(function (require) {
           }
 
           // escape each cell in each row
-          var csvRows = rows.map(function (row) {
+          let csvRows = rows.map(function (row) {
             return row.map(escape);
           });
 
@@ -68,7 +68,7 @@ define(function (require) {
         };
 
         $scope.$watch('table', function () {
-          var table = $scope.table;
+          let table = $scope.table;
 
           if (!table) {
             $scope.rows = null;
@@ -79,14 +79,14 @@ define(function (require) {
           self.csv.filename = ($scope.exportTitle || table.title() || 'table') + '.csv';
           $scope.rows = table.rows;
           $scope.formattedColumns = table.columns.map(function (col, i) {
-            var agg = $scope.table.aggConfig(col);
-            var field = agg.field();
-            var formattedColumn = {
+            let agg = $scope.table.aggConfig(col);
+            let field = agg.field();
+            let formattedColumn = {
               title: col.title,
               filterable: field && field.filterable && agg.schema.group === 'buckets'
             };
 
-            var last = i === (table.columns.length - 1);
+            let last = i === (table.columns.length - 1);
 
             if (last || (agg.schema.group === 'metrics')) {
               formattedColumn.class = 'visualize-table-right';
diff --git a/src/ui/public/agg_table/agg_table_group.js b/src/ui/public/agg_table/agg_table_group.js
index c057bb0512870..1476730c0032a 100644
--- a/src/ui/public/agg_table/agg_table_group.js
+++ b/src/ui/public/agg_table/agg_table_group.js
@@ -24,10 +24,10 @@ define(function (require) {
 
               if (!group || !group.tables.length) return;
 
-              var firstTable = group.tables[0];
-              var params = firstTable.aggConfig && firstTable.aggConfig.params;
+              let firstTable = group.tables[0];
+              let params = firstTable.aggConfig && firstTable.aggConfig.params;
               // render groups that have Table children as if they were rows, because iteration is cleaner
-              var childLayout = (params && !params.row) ? 'columns' : 'rows';
+              let childLayout = (params && !params.row) ? 'columns' : 'rows';
 
               $scope[childLayout] = group.tables;
             });
diff --git a/src/ui/public/agg_types/AggParams.js b/src/ui/public/agg_types/AggParams.js
index 503335d9c567e..7713f6ee38327 100644
--- a/src/ui/public/agg_types/AggParams.js
+++ b/src/ui/public/agg_types/AggParams.js
@@ -2,10 +2,10 @@ define(function (require) {
   return function AggParamsFactory(Private) {
     require('ui/filters/label');
 
-    var _ = require('lodash');
-    var IndexedArray = require('ui/IndexedArray');
+    let _ = require('lodash');
+    let IndexedArray = require('ui/IndexedArray');
 
-    var paramTypeMap = {
+    let paramTypeMap = {
       field: Private(require('ui/agg_types/param_types/field')),
       optioned: Private(require('ui/agg_types/param_types/optioned')),
       regex: Private(require('ui/agg_types/param_types/regex')),
@@ -32,8 +32,8 @@ define(function (require) {
       AggParams.Super.call(this, {
         index: ['name'],
         initialSet: params.map(function (config) {
-          var type = config.name === 'field' ? config.name : config.type;
-          var Class = paramTypeMap[type] || paramTypeMap._default;
+          let type = config.name === 'field' ? config.name : config.type;
+          let Class = paramTypeMap[type] || paramTypeMap._default;
           return new Class(config);
         })
       });
@@ -54,7 +54,7 @@ define(function (require) {
      *         are dependent on the AggParam#write methods which should be studied for each AggType.
      */
     AggParams.prototype.write = function (aggConfig, locals) {
-      var output = { params: {} };
+      let output = { params: {} };
       locals = locals || {};
 
       this.forEach(function (param) {
diff --git a/src/ui/public/agg_types/AggType.js b/src/ui/public/agg_types/AggType.js
index 49e87f6253d6a..e163bf7d70ed6 100644
--- a/src/ui/public/agg_types/AggType.js
+++ b/src/ui/public/agg_types/AggType.js
@@ -1,8 +1,8 @@
 define(function (require) {
   return function AggTypeFactory(Private) {
-    var _ = require('lodash');
-    var AggParams = Private(require('ui/agg_types/AggParams'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let _ = require('lodash');
+    let AggParams = Private(require('ui/agg_types/AggParams'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
     /**
      * Generic AggType Constructor
@@ -141,7 +141,7 @@ define(function (require) {
      * @return {FieldFromat}
      */
     AggType.prototype.getFormat = function (agg) {
-      var field = agg.field();
+      let field = agg.field();
       return field ? field.format : fieldFormats.getDefaultInstance('string');
     };
 
diff --git a/src/ui/public/agg_types/buckets/_bucket_agg_type.js b/src/ui/public/agg_types/buckets/_bucket_agg_type.js
index b76e3911e0c8e..d2310489e73c9 100644
--- a/src/ui/public/agg_types/buckets/_bucket_agg_type.js
+++ b/src/ui/public/agg_types/buckets/_bucket_agg_type.js
@@ -1,7 +1,7 @@
 define(function (require) {
   return function BucketAggTypeProvider(Private) {
-    var _ = require('lodash');
-    var AggType = Private(require('ui/agg_types/AggType'));
+    let _ = require('lodash');
+    let AggType = Private(require('ui/agg_types/AggType'));
 
     _.class(BucketAggType).inherits(AggType);
     function BucketAggType(config) {
diff --git a/src/ui/public/agg_types/buckets/_bucket_count_between.js b/src/ui/public/agg_types/buckets/_bucket_count_between.js
index a969011a9cfec..6e14f38040eeb 100644
--- a/src/ui/public/agg_types/buckets/_bucket_count_between.js
+++ b/src/ui/public/agg_types/buckets/_bucket_count_between.js
@@ -14,19 +14,19 @@ define(function (require) {
      * @return {null|number}
      */
     function bucketCountBetween(aggConfigA, aggConfigB) {
-      var aggs = aggConfigA.vis.aggs.getRequestAggs();
+      let aggs = aggConfigA.vis.aggs.getRequestAggs();
 
-      var aIndex = aggs.indexOf(aggConfigA);
-      var bIndex = aggs.indexOf(aggConfigB);
+      let aIndex = aggs.indexOf(aggConfigA);
+      let bIndex = aggs.indexOf(aggConfigB);
 
       if (aIndex === -1 || bIndex === -1) {
         return null;
       }
 
       // return a negative distance, if b is before a
-      var negative = (aIndex > bIndex);
+      let negative = (aIndex > bIndex);
 
-      var count = aggs
+      let count = aggs
         .slice(Math.min(aIndex, bIndex), Math.max(aIndex, bIndex))
         .reduce(function (count, cfg) {
           if (cfg === aggConfigA || cfg === aggConfigB || cfg.schema.group !== 'buckets') {
diff --git a/src/ui/public/agg_types/buckets/_interval_options.js b/src/ui/public/agg_types/buckets/_interval_options.js
index fa27d2291a01d..6d29637b39787 100644
--- a/src/ui/public/agg_types/buckets/_interval_options.js
+++ b/src/ui/public/agg_types/buckets/_interval_options.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function IntervalOptionsService(Private) {
-    var moment = require('moment');
+    let moment = require('moment');
     require('ui/directives/input_whole_number');
 
     // shorthand
-    var ms = function (type) { return moment.duration(1, type).asMilliseconds(); };
+    let ms = function (type) { return moment.duration(1, type).asMilliseconds(); };
 
     return [
       {
diff --git a/src/ui/public/agg_types/buckets/create_filter/date_histogram.js b/src/ui/public/agg_types/buckets/create_filter/date_histogram.js
index 6040c31ac207b..280e1db1173bf 100644
--- a/src/ui/public/agg_types/buckets/create_filter/date_histogram.js
+++ b/src/ui/public/agg_types/buckets/create_filter/date_histogram.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function createDateHistogramFilterProvider(Private) {
-    var moment = require('moment');
-    var buildRangeFilter = require('ui/filter_manager/lib/range');
+    let moment = require('moment');
+    let buildRangeFilter = require('ui/filter_manager/lib/range');
 
     return function (agg, key) {
-      var start = moment(key);
-      var interval = agg.buckets.getInterval();
+      let start = moment(key);
+      let interval = agg.buckets.getInterval();
 
       return buildRangeFilter(agg.params.field, {
         gte: start.valueOf(),
diff --git a/src/ui/public/agg_types/buckets/create_filter/date_range.js b/src/ui/public/agg_types/buckets/create_filter/date_range.js
index 9b075ee023f03..c5a5839bec6bc 100644
--- a/src/ui/public/agg_types/buckets/create_filter/date_range.js
+++ b/src/ui/public/agg_types/buckets/create_filter/date_range.js
@@ -1,13 +1,13 @@
 define(function (require) {
-  var dateRange = require('ui/utils/date_range');
+  let dateRange = require('ui/utils/date_range');
 
   return function createDateRangeFilterProvider(config) {
-    var buildRangeFilter = require('ui/filter_manager/lib/range');
+    let buildRangeFilter = require('ui/filter_manager/lib/range');
 
     return function (agg, key) {
-      var range = dateRange.parse(key, config.get('dateFormat'));
+      let range = dateRange.parse(key, config.get('dateFormat'));
 
-      var filter = {};
+      let filter = {};
       if (range.from) filter.gte = +range.from;
       if (range.to) filter.lt = +range.to;
       if (range.to && range.from) filter.format = 'epoch_millis';
diff --git a/src/ui/public/agg_types/buckets/create_filter/filters.js b/src/ui/public/agg_types/buckets/create_filter/filters.js
index 89b22f6adc06c..e6b6fb844ac93 100644
--- a/src/ui/public/agg_types/buckets/create_filter/filters.js
+++ b/src/ui/public/agg_types/buckets/create_filter/filters.js
@@ -1,11 +1,11 @@
 define(function (require) {
-  var buildQueryFilter = require('ui/filter_manager/lib/query');
-  var _ = require('lodash');
+  let buildQueryFilter = require('ui/filter_manager/lib/query');
+  let _ = require('lodash');
   return function CreateFilterFiltersProvider(Private) {
     return function (aggConfig, key) {
       // have the aggConfig write agg dsl params
-      var dslFilters = _.get(aggConfig.toDsl(), 'filters.filters');
-      var filter = dslFilters[key];
+      let dslFilters = _.get(aggConfig.toDsl(), 'filters.filters');
+      let filter = dslFilters[key];
 
       if (filter) {
         return buildQueryFilter(filter.query, aggConfig.vis.indexPattern.id);
diff --git a/src/ui/public/agg_types/buckets/create_filter/histogram.js b/src/ui/public/agg_types/buckets/create_filter/histogram.js
index c84883a8fd5b4..271d6c5a3ca1c 100644
--- a/src/ui/public/agg_types/buckets/create_filter/histogram.js
+++ b/src/ui/public/agg_types/buckets/create_filter/histogram.js
@@ -1,9 +1,9 @@
 define(function (require) {
-  var buildRangeFilter = require('ui/filter_manager/lib/range');
+  let buildRangeFilter = require('ui/filter_manager/lib/range');
 
   return function createHistogramFitlerProvider(Private) {
     return function (aggConfig, key) {
-      var value = parseInt(key, 10);
+      let value = parseInt(key, 10);
 
       return buildRangeFilter(
         aggConfig.params.field,
diff --git a/src/ui/public/agg_types/buckets/create_filter/ip_range.js b/src/ui/public/agg_types/buckets/create_filter/ip_range.js
index 7410cb5e4494c..cf08d36685155 100644
--- a/src/ui/public/agg_types/buckets/create_filter/ip_range.js
+++ b/src/ui/public/agg_types/buckets/create_filter/ip_range.js
@@ -1,13 +1,13 @@
 define(function (require) {
-  var CidrMask = require('ui/utils/CidrMask');
-  var buildRangeFilter = require('ui/filter_manager/lib/range');
+  let CidrMask = require('ui/utils/CidrMask');
+  let buildRangeFilter = require('ui/filter_manager/lib/range');
   return function createIpRangeFilterProvider() {
     return function (aggConfig, key) {
       let range;
       if (aggConfig.params.ipRangeType === 'mask') {
         range = new CidrMask(key).getRange();
       } else {
-        var addresses = key.split(/\-/);
+        let addresses = key.split(/\-/);
         range = {
           from: addresses[0],
           to: addresses[1]
diff --git a/src/ui/public/agg_types/buckets/create_filter/range.js b/src/ui/public/agg_types/buckets/create_filter/range.js
index 70af0a2c19097..ecec60143e036 100644
--- a/src/ui/public/agg_types/buckets/create_filter/range.js
+++ b/src/ui/public/agg_types/buckets/create_filter/range.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var buildRangeFilter = require('ui/filter_manager/lib/range');
+  let buildRangeFilter = require('ui/filter_manager/lib/range');
   return function createRangeFilterProvider(Private) {
     return function (aggConfig, key) {
       return buildRangeFilter(
diff --git a/src/ui/public/agg_types/buckets/create_filter/terms.js b/src/ui/public/agg_types/buckets/create_filter/terms.js
index db2361bffe2f3..7ebc9a91e8497 100644
--- a/src/ui/public/agg_types/buckets/create_filter/terms.js
+++ b/src/ui/public/agg_types/buckets/create_filter/terms.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var buildPhraseFilter = require('ui/filter_manager/lib/phrase');
+  let buildPhraseFilter = require('ui/filter_manager/lib/phrase');
   return function createTermsFilterProvider(Private) {
     return function (aggConfig, key) {
       return buildPhraseFilter(aggConfig.params.field, key, aggConfig.vis.indexPattern);
diff --git a/src/ui/public/agg_types/buckets/date_histogram.js b/src/ui/public/agg_types/buckets/date_histogram.js
index afe98ec5c6ffb..e871b221bc097 100644
--- a/src/ui/public/agg_types/buckets/date_histogram.js
+++ b/src/ui/public/agg_types/buckets/date_histogram.js
@@ -1,19 +1,19 @@
 define(function (require) {
   return function DateHistogramAggType(timefilter, config, Private) {
-    var _ = require('lodash');
-    var moment = require('moment');
-    var tzDetect = require('jstimezonedetect').jstz;
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var TimeBuckets = Private(require('ui/time_buckets'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/date_histogram'));
-    var intervalOptions = Private(require('ui/agg_types/buckets/_interval_options'));
-    var configDefaults = Private(require('ui/config/defaults'));
-
-    var detectedTimezone = tzDetect.determine().name();
-    var tzOffset = moment().format('Z');
+    let _ = require('lodash');
+    let moment = require('moment');
+    let tzDetect = require('jstimezonedetect').jstz;
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let TimeBuckets = Private(require('ui/time_buckets'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/date_histogram'));
+    let intervalOptions = Private(require('ui/agg_types/buckets/_interval_options'));
+    let configDefaults = Private(require('ui/config/defaults'));
+
+    let detectedTimezone = tzDetect.determine().name();
+    let tzOffset = moment().format('Z');
 
     function getInterval(agg) {
-      var interval = _.get(agg, ['params', 'interval']);
+      let interval = _.get(agg, ['params', 'interval']);
       if (interval && interval.val === 'custom') interval = _.get(agg, ['params', 'customInterval']);
       return interval;
     }
@@ -34,8 +34,8 @@ define(function (require) {
         date: true
       },
       makeLabel: function (agg) {
-        var output = this.params.write(agg);
-        var params = output.params;
+        let output = this.params.write(agg);
+        let params = output.params;
         return params.field + ' per ' + (output.metricScaleText || output.bucketInterval.description);
       },
       createFilter: createFilter,
@@ -76,7 +76,7 @@ define(function (require) {
           name: 'interval',
           type: 'optioned',
           deserialize: function (state) {
-            var interval = _.find(intervalOptions, {val: state});
+            let interval = _.find(intervalOptions, {val: state});
             return interval || _.find(intervalOptions, function (option) {
               // For upgrading from 4.0.x to 4.1.x - intervals are now stored as 'y' instead of 'year',
               // but this maps the old values to the new values
@@ -93,16 +93,16 @@ define(function (require) {
             setBounds(agg);
             agg.buckets.setInterval(getInterval(agg));
 
-            var interval = agg.buckets.getInterval();
+            let interval = agg.buckets.getInterval();
             output.bucketInterval = interval;
             output.params.interval = interval.expression;
 
-            var isDefaultTimezone = config.get('dateFormat:tz') === configDefaults['dateFormat:tz'].value;
+            let isDefaultTimezone = config.get('dateFormat:tz') === configDefaults['dateFormat:tz'].value;
             output.params.time_zone = isDefaultTimezone ?
               (detectedTimezone || tzOffset) :
               config.get('dateFormat:tz');
 
-            var scaleMetrics = interval.scaled && interval.scale < 1;
+            let scaleMetrics = interval.scaled && interval.scale < 1;
             if (scaleMetrics) {
               scaleMetrics = _.every(agg.vis.aggs.bySchemaGroup.metrics, function (agg) {
                 return agg.type && (agg.type.name === 'count' || agg.type.name === 'sum');
@@ -135,7 +135,7 @@ define(function (require) {
           name: 'extended_bounds',
           default: {},
           write: function (agg, output) {
-            var val = agg.params.extended_bounds;
+            let val = agg.params.extended_bounds;
 
             if (val.min != null || val.max != null) {
               output.params.extended_bounds = {
@@ -146,7 +146,7 @@ define(function (require) {
               return;
             }
 
-            var bounds = timefilter.getActiveBounds();
+            let bounds = timefilter.getActiveBounds();
             if (bounds) {
               output.params.extended_bounds = {
                 min: moment(bounds.min).valueOf(),
diff --git a/src/ui/public/agg_types/buckets/date_range.js b/src/ui/public/agg_types/buckets/date_range.js
index 9296485a425b2..a9144d66a1d5b 100644
--- a/src/ui/public/agg_types/buckets/date_range.js
+++ b/src/ui/public/agg_types/buckets/date_range.js
@@ -1,12 +1,12 @@
 define(function (require) {
-  var moment = require('moment');
-  var dateRange = require('ui/utils/date_range');
+  let moment = require('moment');
+  let dateRange = require('ui/utils/date_range');
   require('ui/directives/validate_date_math');
 
   return function DateRangeAggDefinition(Private, config) {
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/date_range'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/date_range'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
 
     return new BucketAggType({
@@ -14,7 +14,7 @@ define(function (require) {
       title: 'Date Range',
       createFilter: createFilter,
       getKey: function (bucket, key, agg) {
-        var formatter = agg.fieldOwnFormatter('text', fieldFormats.getDefaultInstance('date'));
+        let formatter = agg.fieldOwnFormatter('text', fieldFormats.getDefaultInstance('date'));
         return dateRange.toString(bucket, formatter);
       },
       getFormat: function () {
diff --git a/src/ui/public/agg_types/buckets/filters.js b/src/ui/public/agg_types/buckets/filters.js
index 07d9fffe22687..da31d270a0555 100644
--- a/src/ui/public/agg_types/buckets/filters.js
+++ b/src/ui/public/agg_types/buckets/filters.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function FiltersAggDefinition(Private, Notifier) {
-    var _ = require('lodash');
-    var angular = require('angular');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/filters'));
-    var decorateQuery = Private(require('ui/courier/data_source/_decorate_query'));
-    var notif = new Notifier({ location: 'Filters Agg' });
+    let _ = require('lodash');
+    let angular = require('angular');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/filters'));
+    let decorateQuery = Private(require('ui/courier/data_source/_decorate_query'));
+    let notif = new Notifier({ location: 'Filters Agg' });
 
     return new BucketAggType({
       name: 'filters',
@@ -18,25 +18,25 @@ define(function (require) {
           editor: require('ui/agg_types/controls/filters.html'),
           default: [ {input: {}, label: ''} ],
           write: function (aggConfig, output) {
-            var inFilters = aggConfig.params.filters;
+            let inFilters = aggConfig.params.filters;
             if (!_.size(inFilters)) return;
 
-            var outFilters = _.transform(inFilters, function (filters, filter) {
-              var input = filter.input;
+            let outFilters = _.transform(inFilters, function (filters, filter) {
+              let input = filter.input;
               if (!input) return notif.log('malformed filter agg params, missing "input" query');
 
-              var query = input.query;
+              let query = input.query;
               if (!query) return notif.log('malformed filter agg params, missing "query" on input');
 
               decorateQuery(query);
 
-              var label = filter.label || _.get(query, 'query_string.query') || angular.toJson(query);
+              let label = filter.label || _.get(query, 'query_string.query') || angular.toJson(query);
               filters[label] = input;
             }, {});
 
             if (!_.size(outFilters)) return;
 
-            var params = output.params || (output.params = {});
+            let params = output.params || (output.params = {});
             params.filters = outFilters;
           }
         }
diff --git a/src/ui/public/agg_types/buckets/geo_hash.js b/src/ui/public/agg_types/buckets/geo_hash.js
index 471b051fc7df6..9cb202c32c125 100644
--- a/src/ui/public/agg_types/buckets/geo_hash.js
+++ b/src/ui/public/agg_types/buckets/geo_hash.js
@@ -1,12 +1,12 @@
 define(function (require) {
   return function GeoHashAggDefinition(Private, config) {
-    var _ = require('lodash');
-    var moment = require('moment');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var defaultPrecision = 2;
+    let _ = require('lodash');
+    let moment = require('moment');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let defaultPrecision = 2;
 
     function getPrecision(precision) {
-      var maxPrecision = _.parseInt(config.get('visualization:tileMap:maxPrecision'));
+      let maxPrecision = _.parseInt(config.get('visualization:tileMap:maxPrecision'));
 
       precision = parseInt(precision, 10);
 
diff --git a/src/ui/public/agg_types/buckets/histogram.js b/src/ui/public/agg_types/buckets/histogram.js
index 416b387d01620..13f67952607cc 100644
--- a/src/ui/public/agg_types/buckets/histogram.js
+++ b/src/ui/public/agg_types/buckets/histogram.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function HistogramAggDefinition(Private) {
-    var _ = require('lodash');
-    var moment = require('moment');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/histogram'));
+    let _ = require('lodash');
+    let moment = require('moment');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/histogram'));
 
     require('ui/validateDateInterval');
 
@@ -45,7 +45,7 @@ define(function (require) {
           default: {},
           editor: require('ui/agg_types/controls/extended_bounds.html'),
           write: function (aggConfig, output) {
-            var val = aggConfig.params.extended_bounds;
+            let val = aggConfig.params.extended_bounds;
 
             if (val.min != null || val.max != null) {
               output.params.extended_bounds = {
@@ -57,7 +57,7 @@ define(function (require) {
 
           // called from the editor
           shouldShow: function (aggConfig) {
-            var field = aggConfig.params.field;
+            let field = aggConfig.params.field;
             if (
               field
               && (field.type === 'number' || field.type === 'date')
diff --git a/src/ui/public/agg_types/buckets/ip_range.js b/src/ui/public/agg_types/buckets/ip_range.js
index 2eeee56bd0261..a8e4dc2822a78 100644
--- a/src/ui/public/agg_types/buckets/ip_range.js
+++ b/src/ui/public/agg_types/buckets/ip_range.js
@@ -1,11 +1,11 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   require('ui/directives/validate_ip');
   require('ui/directives/validate_cidr_mask');
 
   return function RangeAggDefinition(Private) {
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/ip_range'));
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/ip_range'));
 
     return new BucketAggType({
       name: 'ip_range',
@@ -36,7 +36,7 @@ define(function (require) {
           },
           editor: require('ui/agg_types/controls/ip_ranges.html'),
           write: function (aggConfig, output) {
-            var ipRangeType = aggConfig.params.ipRangeType;
+            let ipRangeType = aggConfig.params.ipRangeType;
             output.params.ranges = aggConfig.params.ranges[ipRangeType];
           }
         }
diff --git a/src/ui/public/agg_types/buckets/range.js b/src/ui/public/agg_types/buckets/range.js
index d5cb363987181..31fc2bd034494 100644
--- a/src/ui/public/agg_types/buckets/range.js
+++ b/src/ui/public/agg_types/buckets/range.js
@@ -1,13 +1,13 @@
 define(function (require) {
   return function RangeAggDefinition(Private) {
-    var _ = require('lodash');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/range'));
-    var FieldFormat = Private(require('ui/index_patterns/_field_format/FieldFormat'));
-    var RangeKey = Private(require('./RangeKey'));
+    let _ = require('lodash');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/range'));
+    let FieldFormat = Private(require('ui/index_patterns/_field_format/FieldFormat'));
+    let RangeKey = Private(require('./RangeKey'));
 
-    var keyCaches = new WeakMap();
-    var formats = new WeakMap();
+    let keyCaches = new WeakMap();
+    let formats = new WeakMap();
 
     return new BucketAggType({
       name: 'range',
@@ -17,14 +17,14 @@ define(function (require) {
         return aggConfig.params.field.displayName + ' ranges';
       },
       getKey: function (bucket, key, agg) {
-        var keys = keyCaches.get(agg);
+        let keys = keyCaches.get(agg);
 
         if (!keys) {
           keys = new Map();
           keyCaches.set(agg, keys);
         }
 
-        var id = RangeKey.idBucket(bucket);
+        let id = RangeKey.idBucket(bucket);
 
         key = keys.get(id);
         if (!key) {
diff --git a/src/ui/public/agg_types/buckets/significant_terms.js b/src/ui/public/agg_types/buckets/significant_terms.js
index 65b833ea124c9..ebd74ebd83709 100644
--- a/src/ui/public/agg_types/buckets/significant_terms.js
+++ b/src/ui/public/agg_types/buckets/significant_terms.js
@@ -1,8 +1,8 @@
 define(function (require) {
   return function SignificantTermsAggDefinition(Private) {
-    var _ = require('lodash');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/terms'));
+    let _ = require('lodash');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/terms'));
 
     return new BucketAggType({
       name: 'significant_terms',
diff --git a/src/ui/public/agg_types/buckets/terms.js b/src/ui/public/agg_types/buckets/terms.js
index c9eecec142e1b..1bfc5bbf48526 100644
--- a/src/ui/public/agg_types/buckets/terms.js
+++ b/src/ui/public/agg_types/buckets/terms.js
@@ -1,13 +1,13 @@
 define(function (require) {
   return function TermsAggDefinition(Private) {
-    var _ = require('lodash');
-    var BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
-    var bucketCountBetween = Private(require('ui/agg_types/buckets/_bucket_count_between'));
-    var AggConfig = Private(require('ui/Vis/AggConfig'));
-    var Schemas = Private(require('ui/Vis/Schemas'));
-    var createFilter = Private(require('ui/agg_types/buckets/create_filter/terms'));
-
-    var orderAggSchema = (new Schemas([
+    let _ = require('lodash');
+    let BucketAggType = Private(require('ui/agg_types/buckets/_bucket_agg_type'));
+    let bucketCountBetween = Private(require('ui/agg_types/buckets/_bucket_count_between'));
+    let AggConfig = Private(require('ui/Vis/AggConfig'));
+    let Schemas = Private(require('ui/Vis/Schemas'));
+    let createFilter = Private(require('ui/agg_types/buckets/create_filter/terms'));
+
+    let orderAggSchema = (new Schemas([
       {
         group: 'none',
         name: 'orderAgg',
@@ -18,7 +18,7 @@ define(function (require) {
 
     function isNotType(type) {
       return function (agg) {
-        var field = agg.params.field;
+        let field = agg.params.field;
         return !field || field.type !== type;
       };
     }
@@ -27,7 +27,7 @@ define(function (require) {
       name: 'terms',
       title: 'Terms',
       makeLabel: function (agg) {
-        var params = agg.params;
+        let params = agg.params;
         return params.field.displayName + ': ' + params.order.display;
       },
       createFilter: createFilter,
@@ -67,7 +67,7 @@ define(function (require) {
           makeOrderAgg: function (termsAgg, state) {
             state = state || {};
             state.schema = orderAggSchema;
-            var orderAgg = new AggConfig(termsAgg.vis, state);
+            let orderAgg = new AggConfig(termsAgg.vis, state);
             orderAgg.id = termsAgg.id + '-orderAgg';
             return orderAgg;
           },
@@ -80,18 +80,18 @@ define(function (require) {
               }
             };
 
-            var INIT = {}; // flag to know when prevOrderBy has changed
-            var prevOrderBy = INIT;
+            let INIT = {}; // flag to know when prevOrderBy has changed
+            let prevOrderBy = INIT;
 
             $scope.$watch('responseValueAggs', updateOrderAgg);
             $scope.$watch('agg.params.orderBy', updateOrderAgg);
 
             function updateOrderAgg() {
-              var agg = $scope.agg;
-              var aggs = agg.vis.aggs;
-              var params = agg.params;
-              var orderBy = params.orderBy;
-              var paramDef = agg.type.params.byName.orderAgg;
+              let agg = $scope.agg;
+              let aggs = agg.vis.aggs;
+              let params = agg.params;
+              let orderBy = params.orderBy;
+              let paramDef = agg.type.params.byName.orderAgg;
 
               // setup the initial value of orderBy
               if (!orderBy && prevOrderBy === INIT) {
@@ -124,11 +124,11 @@ define(function (require) {
             }
           },
           write: function (agg, output) {
-            var vis = agg.vis;
-            var dir = agg.params.order.val;
-            var order = output.params.order = {};
+            let vis = agg.vis;
+            let dir = agg.params.order.val;
+            let order = output.params.order = {};
 
-            var orderAgg = agg.params.orderAgg || vis.aggs.getResponseAggById(agg.params.orderBy);
+            let orderAgg = agg.params.orderAgg || vis.aggs.getResponseAggById(agg.params.orderBy);
 
             // TODO: This works around an Elasticsearch bug the always casts terms agg scripts to strings
             // thus causing issues with filtering. This probably causes other issues since float might not
@@ -147,7 +147,7 @@ define(function (require) {
               return;
             }
 
-            var orderAggId = orderAgg.id;
+            let orderAggId = orderAgg.id;
             if (orderAgg.parentId) {
               orderAgg = vis.aggs.byId[orderAgg.parentId];
             }
diff --git a/src/ui/public/agg_types/index.js b/src/ui/public/agg_types/index.js
index 16395c10f8aab..c50aad6aecaaf 100644
--- a/src/ui/public/agg_types/index.js
+++ b/src/ui/public/agg_types/index.js
@@ -1,8 +1,8 @@
 define(function (require) {
   return function AggTypeService(Private) {
-    var IndexedArray = require('ui/IndexedArray');
+    let IndexedArray = require('ui/IndexedArray');
 
-    var aggs = {
+    let aggs = {
       metrics: [
         Private(require('ui/agg_types/metrics/count')),
         Private(require('ui/agg_types/metrics/avg')),
diff --git a/src/ui/public/agg_types/metrics/MetricAggType.js b/src/ui/public/agg_types/metrics/MetricAggType.js
index a33d7a9c16437..08a305843c1e2 100644
--- a/src/ui/public/agg_types/metrics/MetricAggType.js
+++ b/src/ui/public/agg_types/metrics/MetricAggType.js
@@ -1,8 +1,8 @@
 define(function (require) {
   return function MetricAggTypeProvider(Private) {
-    var _ = require('lodash');
-    var AggType = Private(require('ui/agg_types/AggType'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let _ = require('lodash');
+    let AggType = Private(require('ui/agg_types/AggType'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
     _.class(MetricAggType).inherits(AggType);
     function MetricAggType(config) {
@@ -23,7 +23,7 @@ define(function (require) {
      */
     MetricAggType.prototype.getValue = function (agg, bucket) {
       // Metric types where an empty set equals `zero`
-      var isSettableToZero = ['cardinality', 'sum'].indexOf(agg.__type.name) !== -1;
+      let isSettableToZero = ['cardinality', 'sum'].indexOf(agg.__type.name) !== -1;
 
       // Return proper values when no buckets are present
       // `Count` handles empty sets properly
@@ -41,7 +41,7 @@ define(function (require) {
      * @return {FieldFromat}
      */
     MetricAggType.prototype.getFormat = function (agg) {
-      var field = agg.field();
+      let field = agg.field();
       return field ? field.format : fieldFormats.getDefaultInstance('number');
     };
 
diff --git a/src/ui/public/agg_types/metrics/avg.js b/src/ui/public/agg_types/metrics/avg.js
index 1a7a1abb755c7..9059c9cf46ce5 100644
--- a/src/ui/public/agg_types/metrics/avg.js
+++ b/src/ui/public/agg_types/metrics/avg.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function AggTypeMetricAvgProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
 
     return new MetricAggType({
       name: 'avg',
diff --git a/src/ui/public/agg_types/metrics/cardinality.js b/src/ui/public/agg_types/metrics/cardinality.js
index f4eef38de8b42..556ef1d142dc8 100644
--- a/src/ui/public/agg_types/metrics/cardinality.js
+++ b/src/ui/public/agg_types/metrics/cardinality.js
@@ -1,7 +1,7 @@
 define(function (require) {
   return function AggTypeMetricCardinalityProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
     return new MetricAggType({
       name: 'cardinality',
diff --git a/src/ui/public/agg_types/metrics/count.js b/src/ui/public/agg_types/metrics/count.js
index a4d49d3084dcb..d455c974d7498 100644
--- a/src/ui/public/agg_types/metrics/count.js
+++ b/src/ui/public/agg_types/metrics/count.js
@@ -1,7 +1,7 @@
 define(function (require) {
   return function AggTypeMetricCountProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
     return new MetricAggType({
       name: 'count',
diff --git a/src/ui/public/agg_types/metrics/getResponseAggConfigClass.js b/src/ui/public/agg_types/metrics/getResponseAggConfigClass.js
index 69314d64a80b8..53ae902a3c704 100644
--- a/src/ui/public/agg_types/metrics/getResponseAggConfigClass.js
+++ b/src/ui/public/agg_types/metrics/getResponseAggConfigClass.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function ResponseAggConfigProvider() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     /**
      * Get the ResponseAggConfig class for an aggConfig,
@@ -31,7 +31,7 @@ define(function (require) {
         this.key = key;
         this.parentId = this.id;
 
-        var subId = String(key);
+        let subId = String(key);
         if (subId.indexOf('.') > -1) {
           this.id = this.parentId + '[\'' + subId.replace(/'/g, '\\\'') + '\']';
         } else {
diff --git a/src/ui/public/agg_types/metrics/max.js b/src/ui/public/agg_types/metrics/max.js
index aef10513b421c..b1f26dfeafc20 100644
--- a/src/ui/public/agg_types/metrics/max.js
+++ b/src/ui/public/agg_types/metrics/max.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function AggTypeMetricMaxProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
 
     return new MetricAggType({
       name: 'max',
diff --git a/src/ui/public/agg_types/metrics/median.js b/src/ui/public/agg_types/metrics/median.js
index 9b8f982ded545..72d390d999749 100644
--- a/src/ui/public/agg_types/metrics/median.js
+++ b/src/ui/public/agg_types/metrics/median.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function AggTypeMetricMaxProvider(Private) {
-    var _ = require('lodash');
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
-    var percentiles = Private(require('ui/agg_types/metrics/percentiles'));
+    let _ = require('lodash');
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
+    let percentiles = Private(require('ui/agg_types/metrics/percentiles'));
 
     return new MetricAggType({
       name: 'median',
diff --git a/src/ui/public/agg_types/metrics/min.js b/src/ui/public/agg_types/metrics/min.js
index 250a5001b1489..e12d0f547e8be 100644
--- a/src/ui/public/agg_types/metrics/min.js
+++ b/src/ui/public/agg_types/metrics/min.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function AggTypeMetricMinProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
 
     return new MetricAggType({
       name: 'min',
diff --git a/src/ui/public/agg_types/metrics/percentile_ranks.js b/src/ui/public/agg_types/metrics/percentile_ranks.js
index 15c3a74e98399..376b8fff62b86 100644
--- a/src/ui/public/agg_types/metrics/percentile_ranks.js
+++ b/src/ui/public/agg_types/metrics/percentile_ranks.js
@@ -1,19 +1,19 @@
 define(function (require) {
   return function AggTypeMetricPercentileRanksProvider(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
-    var valuesEditor = require('ui/agg_types/controls/percentile_ranks.html');
+    let valuesEditor = require('ui/agg_types/controls/percentile_ranks.html');
     // required by the values editor
     require('ui/number_list');
 
-    var valueProps = {
+    let valueProps = {
       makeLabel: function () {
-        var field = this.field();
-        var format = (field && field.format) || fieldFormats.getDefaultInstance('number');
+        let field = this.field();
+        let format = (field && field.format) || fieldFormats.getDefaultInstance('number');
 
         return 'Percentile rank ' + format.convert(this.key, 'text') + ' of "' + this.fieldDisplayName() + '"';
       }
@@ -37,7 +37,7 @@ define(function (require) {
         }
       ],
       getResponseAggs: function (agg) {
-        var ValueAggConfig = getResponseAggConfigClass(agg, valueProps);
+        let ValueAggConfig = getResponseAggConfigClass(agg, valueProps);
 
         return agg.params.values.map(function (value) {
           return new ValueAggConfig(value);
diff --git a/src/ui/public/agg_types/metrics/percentiles.js b/src/ui/public/agg_types/metrics/percentiles.js
index 1b859a4293d47..10a244ea843c3 100644
--- a/src/ui/public/agg_types/metrics/percentiles.js
+++ b/src/ui/public/agg_types/metrics/percentiles.js
@@ -1,17 +1,17 @@
 define(function (require) {
   return function AggTypeMetricPercentilesProvider(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
-    var ordinalSuffix = require('ui/utils/ordinal_suffix');
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
+    let ordinalSuffix = require('ui/utils/ordinal_suffix');
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
-    var percentsEditor = require('ui/agg_types/controls/percentiles.html');
+    let percentsEditor = require('ui/agg_types/controls/percentiles.html');
     // required by the percentiles editor
     require('ui/number_list');
 
-    var valueProps = {
+    let valueProps = {
       makeLabel: function () {
         return ordinalSuffix(this.key) + ' percentile of ' + this.fieldDisplayName();
       }
@@ -35,7 +35,7 @@ define(function (require) {
         }
       ],
       getResponseAggs: function (agg) {
-        var ValueAggConfig = getResponseAggConfigClass(agg, valueProps);
+        let ValueAggConfig = getResponseAggConfigClass(agg, valueProps);
 
         return agg.params.percents.map(function (percent) {
           return new ValueAggConfig(percent);
diff --git a/src/ui/public/agg_types/metrics/stdDeviation.js b/src/ui/public/agg_types/metrics/stdDeviation.js
index 9a7a7ad27ddc5..5888715cb70d8 100644
--- a/src/ui/public/agg_types/metrics/stdDeviation.js
+++ b/src/ui/public/agg_types/metrics/stdDeviation.js
@@ -1,16 +1,16 @@
 define(function (require) {
   return function AggTypeMetricStandardDeviationProvider(Private) {
-    var _ = require('lodash');
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
-    var getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
+    let _ = require('lodash');
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let getResponseAggConfigClass = Private(require('ui/agg_types/metrics/getResponseAggConfigClass'));
 
-    var responseAggConfigProps = {
+    let responseAggConfigProps = {
       valProp: function () {
-        var details = this.keyedDetails[this.key];
+        let details = this.keyedDetails[this.key];
         return details.valProp;
       },
       makeLabel: function () {
-        var details = this.keyedDetails[this.key];
+        let details = this.keyedDetails[this.key];
         return details.title + ' of ' + this.fieldDisplayName();
       },
       keyedDetails: {
@@ -44,7 +44,7 @@ define(function (require) {
       ],
 
       getResponseAggs: function (agg) {
-        var ValueAggConfig = getResponseAggConfigClass(agg, responseAggConfigProps);
+        let ValueAggConfig = getResponseAggConfigClass(agg, responseAggConfigProps);
 
         return [
           new ValueAggConfig('std_lower'),
diff --git a/src/ui/public/agg_types/metrics/sum.js b/src/ui/public/agg_types/metrics/sum.js
index 5eced3aea75b8..75eb482d726bd 100644
--- a/src/ui/public/agg_types/metrics/sum.js
+++ b/src/ui/public/agg_types/metrics/sum.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function AggTypeMetricSumProvider(Private) {
-    var MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
+    let MetricAggType = Private(require('ui/agg_types/metrics/MetricAggType'));
 
     return new MetricAggType({
       name: 'sum',
diff --git a/src/ui/public/agg_types/param_types/base.js b/src/ui/public/agg_types/param_types/base.js
index e0be2ae5b13e6..19d8cfb331dbe 100644
--- a/src/ui/public/agg_types/param_types/base.js
+++ b/src/ui/public/agg_types/param_types/base.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function BaseAggParamFactory() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     function BaseAggParam(config) {
       _.assign(this, config);
diff --git a/src/ui/public/agg_types/param_types/field.js b/src/ui/public/agg_types/param_types/field.js
index 8a697da80f9a3..0d6550867d638 100644
--- a/src/ui/public/agg_types/param_types/field.js
+++ b/src/ui/public/agg_types/param_types/field.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function FieldAggParamFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var editorHtml = require('ui/agg_types/controls/field.html');
-    var BaseAggParam = Private(require('ui/agg_types/param_types/base'));
-    var SavedObjectNotFound = require('ui/errors').SavedObjectNotFound;
+    let editorHtml = require('ui/agg_types/controls/field.html');
+    let BaseAggParam = Private(require('ui/agg_types/param_types/base'));
+    let SavedObjectNotFound = require('ui/errors').SavedObjectNotFound;
 
     _.class(FieldAggParam).inherits(BaseAggParam);
     function FieldAggParam(config) {
@@ -33,7 +33,7 @@ define(function (require) {
      * @return {field}
      */
     FieldAggParam.prototype.deserialize = function (fieldName, aggConfig) {
-      var field = aggConfig.vis.indexPattern.fields.byName[fieldName];
+      let field = aggConfig.vis.indexPattern.fields.byName[fieldName];
 
       if (!field) {
         throw new SavedObjectNotFound('index-pattern-field', fieldName);
@@ -53,7 +53,7 @@ define(function (require) {
      * @return {undefined}
      */
     FieldAggParam.prototype.write = function (aggConfig, output) {
-      var field = aggConfig.params.field;
+      let field = aggConfig.params.field;
 
       if (field.scripted) {
         output.params.script = field.script;
diff --git a/src/ui/public/agg_types/param_types/optioned.js b/src/ui/public/agg_types/param_types/optioned.js
index 5d42ddf4e89bd..fd7e692d8c363 100644
--- a/src/ui/public/agg_types/param_types/optioned.js
+++ b/src/ui/public/agg_types/param_types/optioned.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function OptionedAggParamFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var IndexedArray = require('ui/IndexedArray');
-    var BaseAggParam = Private(require('ui/agg_types/param_types/base'));
+    let IndexedArray = require('ui/IndexedArray');
+    let BaseAggParam = Private(require('ui/agg_types/param_types/base'));
 
     _.class(OptionedAggParam).inherits(BaseAggParam);
     function OptionedAggParam(config) {
diff --git a/src/ui/public/agg_types/param_types/raw_json.js b/src/ui/public/agg_types/param_types/raw_json.js
index 5cc0dcd147707..ad4f2b48712a8 100644
--- a/src/ui/public/agg_types/param_types/raw_json.js
+++ b/src/ui/public/agg_types/param_types/raw_json.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function RawJSONAggParamFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var BaseAggParam = Private(require('ui/agg_types/param_types/base'));
-    var editorHtml = require('ui/agg_types/controls/raw_json.html');
+    let BaseAggParam = Private(require('ui/agg_types/param_types/base'));
+    let editorHtml = require('ui/agg_types/controls/raw_json.html');
 
     _.class(RawJSONAggParam).inherits(BaseAggParam);
     function RawJSONAggParam(config) {
@@ -26,7 +26,7 @@ define(function (require) {
      */
     RawJSONAggParam.prototype.write = function (aggConfig, output) {
       let paramJSON;
-      var param = aggConfig.params[this.name];
+      let param = aggConfig.params[this.name];
 
       if (!param) {
         return;
@@ -45,7 +45,7 @@ define(function (require) {
           .keys()
           .union(_.keys(b))
           .transform(function (dest, key) {
-            var val = compare(a[key], b[key]);
+            let val = compare(a[key], b[key]);
             if (val !== undefined) dest[key] = val;
           }, {})
           .value();
diff --git a/src/ui/public/agg_types/param_types/regex.js b/src/ui/public/agg_types/param_types/regex.js
index ea1a3165b5c40..9b5ef8cd64004 100644
--- a/src/ui/public/agg_types/param_types/regex.js
+++ b/src/ui/public/agg_types/param_types/regex.js
@@ -1,14 +1,14 @@
 define(function (require) {
   return function RegexAggParamFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var BaseAggParam = Private(require('ui/agg_types/param_types/base'));
-    var editorHtml = require('ui/agg_types/controls/regular_expression.html');
+    let BaseAggParam = Private(require('ui/agg_types/param_types/base'));
+    let editorHtml = require('ui/agg_types/controls/regular_expression.html');
 
     _.class(RegexAggParam).inherits(BaseAggParam);
     function RegexAggParam(config) {
       // Java RegExp flags
-      var flags = [
+      let flags = [
         'CANON_EQ',
         'CASE_INSENSITIVE',
         'COMMENTS',
@@ -46,15 +46,15 @@ define(function (require) {
      * @return {undefined}
      */
     RegexAggParam.prototype.write = function (aggConfig, output) {
-      var param = aggConfig.params[this.name];
-      var paramType = aggConfig.type.params.byName[this.name];
+      let param = aggConfig.params[this.name];
+      let paramType = aggConfig.type.params.byName[this.name];
 
       // clear aggParam if pattern is not set or is disabled
       if (!param || !param.pattern || !param.pattern.length || paramType.disabled(aggConfig)) {
         return;
       }
 
-      var obj = {
+      let obj = {
         pattern: param.pattern
       };
 
diff --git a/src/ui/public/agg_types/param_types/string.js b/src/ui/public/agg_types/param_types/string.js
index e6135741e8971..76014d93d75e4 100644
--- a/src/ui/public/agg_types/param_types/string.js
+++ b/src/ui/public/agg_types/param_types/string.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function FieldAggParamFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var editorHtml = require('ui/agg_types/controls/string.html');
-    var BaseAggParam = Private(require('ui/agg_types/param_types/base'));
+    let editorHtml = require('ui/agg_types/controls/string.html');
+    let BaseAggParam = Private(require('ui/agg_types/param_types/base'));
 
     _.class(ScriptAggParam).inherits(BaseAggParam);
     function ScriptAggParam(config) {
diff --git a/src/ui/public/bind/bind.js b/src/ui/public/bind/bind.js
index fe229ad68adef..7863a202d3f4e 100644
--- a/src/ui/public/bind/bind.js
+++ b/src/ui/public/bind/bind.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var angular = require('angular');
+  let _ = require('lodash');
+  let angular = require('angular');
 
   require('ui/modules').get('kibana')
   .config(function ($provide) {
@@ -27,26 +27,26 @@ define(function (require) {
        * @return {undefined}
        */
       $delegate.constructor.prototype.$bind = function (to, from, $sourceScope) {
-        var $source = $sourceScope || this.$parent;
-        var $target = this;
+        let $source = $sourceScope || this.$parent;
+        let $target = this;
 
         // parse expressions
-        var $to = $parse(to);
+        let $to = $parse(to);
         if (!$to.assign) errorNotAssignable(to, from);
-        var $from = $parse(from);
+        let $from = $parse(from);
 
         // bind scopes to expressions
-        var getTarget = function () { return $to($target); };
-        var setTarget = function (v) { return $to.assign($target, v); };
-        var getSource = function () { return $from($source); };
-        var setSource = function (v) { return $from.assignOrFail($source, v); };
+        let getTarget = function () { return $to($target); };
+        let setTarget = function (v) { return $to.assign($target, v); };
+        let getSource = function () { return $from($source); };
+        let setSource = function (v) { return $from.assignOrFail($source, v); };
 
         // to support writing from the child to the parent we need to know
         // which source has changed. Track the source value and anytime it
         // changes (even if the target value changed too) push from source
         // to target. If the source hasn't changed then the change is from
         // the target and push accordingly
-        var lastSourceVal = getSource();
+        let lastSourceVal = getSource();
 
         $from.assignOrFail = $from.assign || function () {
           // revert the change and throw an error, child writes aren't supported
@@ -55,19 +55,19 @@ define(function (require) {
         };
 
         // if we are syncing down a literal, then we use loose equality check
-        var strict = !$from.literal;
-        var compare = strict ? strictEquality : angular.equals;
+        let strict = !$from.literal;
+        let compare = strict ? strictEquality : angular.equals;
 
 
         // push the initial value down, start off in sync
         setTarget(lastSourceVal);
 
         $target.$watch(function () {
-          var sourceVal = getSource();
-          var targetVal = getTarget();
+          let sourceVal = getSource();
+          let targetVal = getTarget();
 
-          var outOfSync = !compare(sourceVal, targetVal);
-          var sourceChanged = outOfSync && !compare(sourceVal, lastSourceVal);
+          let outOfSync = !compare(sourceVal, targetVal);
+          let sourceChanged = outOfSync && !compare(sourceVal, lastSourceVal);
 
           if (sourceChanged) setTarget(sourceVal);
           else if (outOfSync) setSource(targetVal);
diff --git a/src/ui/public/chrome/TabCollection.js b/src/ui/public/chrome/TabCollection.js
index 7287d1a0e7b6b..e8617319ef3d9 100644
--- a/src/ui/public/chrome/TabCollection.js
+++ b/src/ui/public/chrome/TabCollection.js
@@ -1,13 +1,13 @@
-var _ = require('lodash');
+let _ = require('lodash');
 var { startsWith, get, set, omit, wrap, pick } = require('lodash');
-var Tab = require('ui/chrome/Tab');
+let Tab = require('ui/chrome/Tab');
 var { parse } = require('url');
 
 function TabCollection(opts = {}) {
-  var tabs = [];
-  var specs = null;
-  var defaults = opts.defaults || {};
-  var activeTab = null;
+  let tabs = [];
+  let specs = null;
+  let defaults = opts.defaults || {};
+  let activeTab = null;
 
   this.set = function (_specs) {
     specs = _.cloneDeep([].concat(_specs || []));
diff --git a/src/ui/public/chrome/api/angular.js b/src/ui/public/chrome/api/angular.js
index f9a0eba6c0a92..79af632c405b8 100644
--- a/src/ui/public/chrome/api/angular.js
+++ b/src/ui/public/chrome/api/angular.js
@@ -1,10 +1,10 @@
-var _ = require('lodash');
+let _ = require('lodash');
 
 module.exports = function (chrome, internals) {
 
   chrome.setupAngular = function () {
-    var modules = require('ui/modules');
-    var kibana = modules.get('kibana');
+    let modules = require('ui/modules');
+    let kibana = modules.get('kibana');
 
     _.forOwn(chrome.getInjected(), function (val, name) {
       kibana.value(name, val);
@@ -16,7 +16,7 @@ module.exports = function (chrome, internals) {
     .value('buildSha', internals.buildSha)
     .value('sessionId', Date.now())
     .value('esUrl', (function () {
-      var a = document.createElement('a');
+      let a = document.createElement('a');
       a.href = chrome.addBasePath('/elasticsearch');
       return a.href;
     }()))
diff --git a/src/ui/public/chrome/api/controls.js b/src/ui/public/chrome/api/controls.js
index 116e37411cff5..4473e23d0e957 100644
--- a/src/ui/public/chrome/api/controls.js
+++ b/src/ui/public/chrome/api/controls.js
@@ -1,4 +1,4 @@
-var _ = require('lodash');
+let _ = require('lodash');
 
 module.exports = function (chrome, internals) {
   /**
@@ -10,7 +10,7 @@ module.exports = function (chrome, internals) {
    *     determines if the Kibana chrome should be displayed
    */
 
-  var def = true;
+  let def = true;
   internals.setVisibleDefault = (_def) => def = Boolean(_def);
 
   /**
diff --git a/src/ui/public/chrome/api/nav.js b/src/ui/public/chrome/api/nav.js
index adc854c61cffe..75b9dca2d0469 100644
--- a/src/ui/public/chrome/api/nav.js
+++ b/src/ui/public/chrome/api/nav.js
@@ -15,10 +15,10 @@ export default function (chrome, internals) {
   };
 
   chrome.addBasePath = function (url) {
-    var isUrl = url && isString(url);
+    let isUrl = url && isString(url);
     if (!isUrl) return url;
 
-    var parsed = parse(url, true);
+    let parsed = parse(url, true);
     if (!parsed.host && parsed.pathname) {
       if (parsed.pathname[0] === '/') {
         parsed.pathname = chrome.getBasePath() + parsed.pathname;
@@ -46,7 +46,7 @@ export default function (chrome, internals) {
   internals.nav.forEach(link => {
     // convert all link urls to absolute urls
 
-    var a = document.createElement('a');
+    let a = document.createElement('a');
     a.setAttribute('href', link.url);
     link.url = a.href;
     link.lastSubUrl = chrome.getLastSubUrlFor(link.url);
diff --git a/src/ui/public/chrome/api/tabs.js b/src/ui/public/chrome/api/tabs.js
index 128f5ca8c267e..a88c2d4e3f1a3 100644
--- a/src/ui/public/chrome/api/tabs.js
+++ b/src/ui/public/chrome/api/tabs.js
@@ -1,5 +1,5 @@
-var _ = require('lodash');
-var TabCollection = require('../TabCollection');
+let _ = require('lodash');
+let TabCollection = require('../TabCollection');
 
 module.exports = function (chrome, internals) {
 
@@ -91,7 +91,7 @@ module.exports = function (chrome, internals) {
   // create a getter for properties of the active tab
   function activeGetter(prop) {
     return function (def) {
-      var active = chrome.getActiveTab();
+      let active = chrome.getActiveTab();
       return !active ? def : active[prop];
     };
   }
diff --git a/src/ui/public/chrome/api/template.js b/src/ui/public/chrome/api/template.js
index f45e3776caa88..32e39474163c3 100644
--- a/src/ui/public/chrome/api/template.js
+++ b/src/ui/public/chrome/api/template.js
@@ -1,4 +1,4 @@
-var _ = require('lodash');
+let _ = require('lodash');
 
 module.exports = function (chrome, internals) {
 
diff --git a/src/ui/public/chrome/api/theme.js b/src/ui/public/chrome/api/theme.js
index 59b2dea3b3c24..440ca2a55bc72 100644
--- a/src/ui/public/chrome/api/theme.js
+++ b/src/ui/public/chrome/api/theme.js
@@ -1,4 +1,4 @@
-var _ = require('lodash');
+let _ = require('lodash');
 
 module.exports = function (chrome, internals) {
   /**
@@ -66,7 +66,7 @@ module.exports = function (chrome, internals) {
    * @return {chrome}
    */
   chrome.addApplicationClass = function (val) {
-    var classes = internals.applicationClasses || [];
+    let classes = internals.applicationClasses || [];
     classes.push(val);
     classes = _.uniq(classes);
 
@@ -81,8 +81,8 @@ module.exports = function (chrome, internals) {
    * @return {chrome}
    */
   chrome.removeApplicationClass = function (val) {
-    var classesToRemove = [].concat(val || []);
-    var classes = internals.applicationClasses || [];
+    let classesToRemove = [].concat(val || []);
+    let classes = internals.applicationClasses || [];
     _.pull(classes, ...classesToRemove);
 
     internals.applicationClasses = classes;
diff --git a/src/ui/public/chrome/chrome.js b/src/ui/public/chrome/chrome.js
index 62d353623c18d..d7bda2109c130 100644
--- a/src/ui/public/chrome/chrome.js
+++ b/src/ui/public/chrome/chrome.js
@@ -1,17 +1,17 @@
 require('babel/polyfill');
 
-var _ = require('lodash');
-var $ = require('jquery');
-var angular = require('angular');
+let _ = require('lodash');
+let $ = require('jquery');
+let angular = require('angular');
 
 require('ui/timefilter');
 require('ui/private');
 require('ui/promises');
 
-var metadata = require('ui/metadata');
+let metadata = require('ui/metadata');
 
-var chrome = {};
-var internals = _.defaults(
+let chrome = {};
+let internals = _.defaults(
   _.cloneDeep(metadata),
   {
     basePath: '',
diff --git a/src/ui/public/chrome/context.js b/src/ui/public/chrome/context.js
index 2202f7900311d..96280e17d74f3 100644
--- a/src/ui/public/chrome/context.js
+++ b/src/ui/public/chrome/context.js
@@ -1,13 +1,13 @@
 define(function (require) {
-  var _ = require('lodash');
-  var ConfigTemplate = require('ui/ConfigTemplate');
+  let _ = require('lodash');
+  let ConfigTemplate = require('ui/ConfigTemplate');
 
   require('ui/modules')
   .get('kibana')
   // TODO: all of this really belongs in the timepicker
   .directive('chromeContext', function (timefilter, globalState) {
 
-    var listenForUpdates = _.once(function ($scope) {
+    let listenForUpdates = _.once(function ($scope) {
       $scope.$listen(timefilter, 'update', function (newVal, oldVal) {
         globalState.time = _.clone(timefilter.time);
         globalState.refreshInterval = _.clone(timefilter.refreshInterval);
diff --git a/src/ui/public/chrome/directives/app_switcher/app_switcher.js b/src/ui/public/chrome/directives/app_switcher/app_switcher.js
index 70571d2f31f2a..94ebb3c83e478 100644
--- a/src/ui/public/chrome/directives/app_switcher/app_switcher.js
+++ b/src/ui/public/chrome/directives/app_switcher/app_switcher.js
@@ -1,8 +1,8 @@
-var parse = require('url').parse;
-var bindKey = require('lodash').bindKey;
+let parse = require('url').parse;
+let bindKey = require('lodash').bindKey;
 
 require('../app_switcher/app_switcher.less');
-var DomLocationProvider = require('ui/domLocation');
+let DomLocationProvider = require('ui/domLocation');
 
 require('ui/modules')
 .get('kibana')
@@ -12,7 +12,7 @@ require('ui/modules')
     template: require('./app_switcher.html'),
     controllerAs: 'switcher',
     controller: function ($scope, Private) {
-      var domLocation = Private(DomLocationProvider);
+      let domLocation = Private(DomLocationProvider);
 
       // since we render this in an isolate scope we can't "require: ^chrome", but
       // rather than remove all helpfull checks we can just check here.
@@ -29,11 +29,11 @@ require('ui/modules')
           return;
         }
 
-        var toParsed = parse(event.delegateTarget.href);
-        var fromParsed = parse(domLocation.href);
-        var sameProto = toParsed.protocol === fromParsed.protocol;
-        var sameHost = toParsed.host === fromParsed.host;
-        var samePath = toParsed.path === fromParsed.path;
+        let toParsed = parse(event.delegateTarget.href);
+        let fromParsed = parse(domLocation.href);
+        let sameProto = toParsed.protocol === fromParsed.protocol;
+        let sameHost = toParsed.host === fromParsed.host;
+        let samePath = toParsed.path === fromParsed.path;
 
         if (sameProto && sameHost && samePath) {
           toParsed.hash && domLocation.reload();
diff --git a/src/ui/public/collapsible_sidebar/collapsible_sidebar.js b/src/ui/public/collapsible_sidebar/collapsible_sidebar.js
index b880ebfbf37c6..269faf797a9ee 100644
--- a/src/ui/public/collapsible_sidebar/collapsible_sidebar.js
+++ b/src/ui/public/collapsible_sidebar/collapsible_sidebar.js
@@ -1,22 +1,22 @@
 define(function (require) {
   require('ui/collapsible_sidebar/collapsible_sidebar.less');
 
-  var _ = require('lodash');
-  var $ = require('jquery');
+  let _ = require('lodash');
+  let $ = require('jquery');
 
   require('ui/modules')
   .get('kibana')
   .directive('collapsibleSidebar', function () {
     // simply a list of all of all of angulars .col-md-* classes except 12
-    var listOfWidthClasses = _.times(11, function (i) { return 'col-md-' + i; });
+    let listOfWidthClasses = _.times(11, function (i) { return 'col-md-' + i; });
 
     return {
       restrict: 'C',
       link: function ($scope, $elem) {
-        var $collapser = $('<div class="sidebar-collapser"><div class="chevron-cont"></div></div>');
-        var $siblings = $elem.siblings();
+        let $collapser = $('<div class="sidebar-collapser"><div class="chevron-cont"></div></div>');
+        let $siblings = $elem.siblings();
 
-        var siblingsClass = listOfWidthClasses.reduce(function (prev, className) {
+        let siblingsClass = listOfWidthClasses.reduce(function (prev, className) {
           if (prev) return prev;
           return $siblings.hasClass(className) && className;
         }, false);
diff --git a/src/ui/public/config/_delayed_updater.js b/src/ui/public/config/_delayed_updater.js
index 0db77a70ba959..b6d82869c4b5e 100644
--- a/src/ui/public/config/_delayed_updater.js
+++ b/src/ui/public/config/_delayed_updater.js
@@ -1,15 +1,15 @@
 define(function (require) {
   return function DelayedUpdaterFactory(Private, $rootScope, Promise, Notifier) {
-    var notify = new Notifier();
-    var _ = require('lodash');
-    var angular = require('angular');
+    let notify = new Notifier();
+    let _ = require('lodash');
+    let angular = require('angular');
 
-    var vals = Private(require('ui/config/_vals'));
+    let vals = Private(require('ui/config/_vals'));
 
     return function DelayedUpdater(doc) {
-      var updater = this;
-      var queue = [];
-      var log = {};
+      let updater = this;
+      let queue = [];
+      let log = {};
       let timer;
 
       updater.fire = function () {
@@ -21,8 +21,8 @@ define(function (require) {
 
         let method;
         let body;
-        var updated = [];
-        var deleted = [];
+        let updated = [];
+        let deleted = [];
 
         // seperate the log into lists
         Object.keys(log).forEach(function (key) {
@@ -53,8 +53,8 @@ define(function (require) {
       };
 
       updater.update = function (key, val, silentAndLocal) {
-        var newVal = val;
-        var oldVal = vals[key];
+        let newVal = val;
+        let oldVal = vals[key];
 
         if (angular.equals(newVal, oldVal)) {
           return Promise.resolve();
@@ -70,7 +70,7 @@ define(function (require) {
 
         if (silentAndLocal) return Promise.resolve();
 
-        var defer = Promise.defer();
+        let defer = Promise.defer();
         queue.push(defer);
         notify.log('config change: ' + key + ': ' + oldVal + ' -> ' + newVal);
         $rootScope.$broadcast('change:config.' + key, newVal, oldVal);
diff --git a/src/ui/public/config/config.js b/src/ui/public/config/config.js
index ce713254aa6d3..15c7757a8e264 100644
--- a/src/ui/public/config/config.js
+++ b/src/ui/public/config/config.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana/config', [
+  let module = require('ui/modules').get('kibana/config', [
     'kibana/notify'
   ]);
 
@@ -9,15 +9,15 @@ define(function (require) {
 
   // service for delivering config variables to everywhere else
   module.service('config', function (Private, Notifier, kbnVersion, kbnIndex, $rootScope, buildNum) {
-    var config = this;
+    let config = this;
 
-    var angular = require('angular');
-    var _ = require('lodash');
-    var defaults = Private(require('ui/config/defaults'));
-    var DelayedUpdater = Private(require('ui/config/_delayed_updater'));
-    var vals = Private(require('ui/config/_vals'));
+    let angular = require('angular');
+    let _ = require('lodash');
+    let defaults = Private(require('ui/config/defaults'));
+    let DelayedUpdater = Private(require('ui/config/_delayed_updater'));
+    let vals = Private(require('ui/config/_vals'));
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Config'
     });
 
@@ -25,8 +25,8 @@ define(function (require) {
     // update once it is requested by calling #set() or #clear().
     let updater;
 
-    var DocSource = Private(require('ui/courier/data_source/doc_source'));
-    var doc = (new DocSource())
+    let DocSource = Private(require('ui/courier/data_source/doc_source'));
+    let doc = (new DocSource())
       .index(kbnIndex)
       .type('config')
       .id(kbnVersion);
@@ -42,13 +42,13 @@ define(function (require) {
      * @return {Promise} - Resolved when the config loads initially
      */
     config.init = _.once(function () {
-      var complete = notify.lifecycle('config init');
+      let complete = notify.lifecycle('config init');
 
       return (function getDoc() {
 
         // used to apply an entire es response to the vals, silentAndLocal will prevent
         // event/notifications/writes from occuring.
-        var applyMassUpdate = function (resp, silentAndLocal) {
+        let applyMassUpdate = function (resp, silentAndLocal) {
           _.union(_.keys(resp._source), _.keys(vals)).forEach(function (key) {
             change(key, resp._source[key], silentAndLocal);
           });
@@ -127,7 +127,7 @@ define(function (require) {
     config.$bind = function ($scope, key, property) {
       if (!property) property = key;
 
-      var update = function () {
+      let update = function () {
         $scope[property] = config.get(key);
       };
 
diff --git a/src/ui/public/config/defaults.js b/src/ui/public/config/defaults.js
index b2643442db3d7..7122b56366c53 100644
--- a/src/ui/public/config/defaults.js
+++ b/src/ui/public/config/defaults.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var moment = require('moment-timezone');
-  var _ = require('lodash');
+  let moment = require('moment-timezone');
+  let _ = require('lodash');
 
   return function configDefaultsProvider() {
     // wraped in provider so that a new instance is given to each app/test
diff --git a/src/ui/public/courier/_redirect_when_missing.js b/src/ui/public/courier/_redirect_when_missing.js
index b7d9d4770d34f..f208e01f89add 100644
--- a/src/ui/public/courier/_redirect_when_missing.js
+++ b/src/ui/public/courier/_redirect_when_missing.js
@@ -1,10 +1,10 @@
 define(function (require) {
-  var errors = require('ui/errors');
+  let errors = require('ui/errors');
 
   return function RedirectWhenMissingFn($location, kbnUrl, Notifier, Promise) {
-    var SavedObjectNotFound = errors.SavedObjectNotFound;
+    let SavedObjectNotFound = errors.SavedObjectNotFound;
 
-    var notify = new Notifier();
+    let notify = new Notifier();
 
     /**
      * Creates an error handler that will redirect to a url when a SavedObjectNotFound
@@ -23,7 +23,7 @@ define(function (require) {
         // if this error is not "404", rethrow
         if (!(err instanceof SavedObjectNotFound)) throw err;
 
-        var url = mapping[err.savedObjectType] || mapping['*'];
+        let url = mapping[err.savedObjectType] || mapping['*'];
         if (!url) url = '/';
 
         url += (url.indexOf('?') >= 0 ? '&' : '?') + `notFound=${err.savedObjectType}`;
diff --git a/src/ui/public/courier/_request_queue.js b/src/ui/public/courier/_request_queue.js
index e6dcf78957c66..f4e99c1a1696d 100644
--- a/src/ui/public/courier/_request_queue.js
+++ b/src/ui/public/courier/_request_queue.js
@@ -1,13 +1,13 @@
 define(function (require) {
   return function PendingRequestList() {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     /**
      * Queue of pending requests, requests are removed as
      * they are processed by fetch.[sourceType]().
      * @type {Array}
      */
-    var queue = [];
+    let queue = [];
 
     queue.getInactive = function (/* strategies */) {
       return queue.get.apply(queue, arguments)
@@ -22,7 +22,7 @@ define(function (require) {
 
     queue.get = function (...strategies) {
       return queue.filter(function (req) {
-        var strategyMatch = !strategies.length;
+        let strategyMatch = !strategies.length;
         if (!strategyMatch) {
           strategyMatch = strategies.some(function (strategy) {
             return req.strategy === strategy;
diff --git a/src/ui/public/courier/courier.js b/src/ui/public/courier/courier.js
index a9caf469089d3..5ccfeedbb4815 100644
--- a/src/ui/public/courier/courier.js
+++ b/src/ui/public/courier/courier.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var errors = require('ui/errors');
-  var _ = require('lodash');
+  let errors = require('ui/errors');
+  let _ = require('lodash');
 
   require('ui/es');
   require('ui/promises');
@@ -10,18 +10,18 @@ define(function (require) {
   require('ui/modules').get('kibana/courier')
   .service('courier', function ($rootScope, Private, Promise, indexPatterns, Notifier) {
     function Courier() {
-      var self = this;
+      let self = this;
 
-      var DocSource = Private(require('ui/courier/data_source/doc_source'));
-      var SearchSource = Private(require('ui/courier/data_source/search_source'));
-      var searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
+      let DocSource = Private(require('ui/courier/data_source/doc_source'));
+      let SearchSource = Private(require('ui/courier/data_source/search_source'));
+      let searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
 
-      var requestQueue = Private(require('ui/courier/_request_queue'));
-      var errorHandlers = Private(require('ui/courier/_error_handlers'));
+      let requestQueue = Private(require('ui/courier/_request_queue'));
+      let errorHandlers = Private(require('ui/courier/_error_handlers'));
 
-      var fetch = Private(require('ui/courier/fetch/fetch'));
-      var docLooper = self.docLooper = Private(require('ui/courier/looper/doc'));
-      var searchLooper = self.searchLooper = Private(require('ui/courier/looper/search'));
+      let fetch = Private(require('ui/courier/fetch/fetch'));
+      let docLooper = self.docLooper = Private(require('ui/courier/looper/doc'));
+      let searchLooper = self.searchLooper = Private(require('ui/courier/looper/search'));
 
       // expose some internal modules
       self.setRootSearchSource = Private(require('ui/courier/data_source/_root_search_source')).set;
@@ -33,7 +33,7 @@ define(function (require) {
       self.DocSource = DocSource;
       self.SearchSource = SearchSource;
 
-      var HastyRefresh = errors.HastyRefresh;
+      let HastyRefresh = errors.HastyRefresh;
 
       /**
        * update the time between automatic search requests
@@ -121,8 +121,8 @@ define(function (require) {
 
       // Listen for refreshInterval changes
       $rootScope.$watchCollection('timefilter.refreshInterval', function () {
-        var refreshValue = _.get($rootScope, 'timefilter.refreshInterval.value');
-        var refreshPause = _.get($rootScope, 'timefilter.refreshInterval.pause');
+        let refreshValue = _.get($rootScope, 'timefilter.refreshInterval.value');
+        let refreshPause = _.get($rootScope, 'timefilter.refreshInterval.pause');
         if (_.isNumber(refreshValue) && !refreshPause) {
           self.fetchInterval(refreshValue);
         } else {
@@ -130,7 +130,7 @@ define(function (require) {
         }
       });
 
-      var onFatalDefer = Promise.defer();
+      let onFatalDefer = Promise.defer();
       onFatalDefer.promise.then(self.close);
       Notifier.fatalCallbacks.push(onFatalDefer.resolve);
     }
diff --git a/src/ui/public/courier/data_source/_abstract.js b/src/ui/public/courier/data_source/_abstract.js
index f66996048e1c4..cbd13a879d7a7 100644
--- a/src/ui/public/courier/data_source/_abstract.js
+++ b/src/ui/public/courier/data_source/_abstract.js
@@ -1,14 +1,14 @@
 define(function (require) {
-  var _ = require('lodash');
-  var angular = require('angular');
+  let _ = require('lodash');
+  let angular = require('angular');
 
   return function SourceAbstractFactory(Private, Promise, PromiseEmitter) {
-    var requestQueue = Private(require('ui/courier/_request_queue'));
-    var errorHandlers = Private(require('ui/courier/_error_handlers'));
-    var courierFetch = Private(require('ui/courier/fetch/fetch'));
+    let requestQueue = Private(require('ui/courier/_request_queue'));
+    let errorHandlers = Private(require('ui/courier/_error_handlers'));
+    let courierFetch = Private(require('ui/courier/fetch/fetch'));
 
     function SourceAbstract(initialState, strategy) {
-      var self = this;
+      let self = this;
       self._instanceid = _.uniqueId('data_source');
 
       self._state = (function () {
@@ -51,7 +51,7 @@ define(function (require) {
      * @return {any} - the value found
      */
     SourceAbstract.prototype.get = function (name) {
-      var self = this;
+      let self = this;
       while (self) {
         if (self._state[name] !== void 0) return self._state[name];
         self = self.getParent();
@@ -73,7 +73,7 @@ define(function (require) {
      *   string of the state value to set
      */
     SourceAbstract.prototype.set = function (state, val) {
-      var self = this;
+      let self = this;
 
       if (typeof state === 'string') {
         // the getter and setter methods check for undefined explicitly
@@ -119,7 +119,7 @@ define(function (require) {
      * @return {Promise}
      */
     SourceAbstract.prototype.onResults = function (handler) {
-      var self = this;
+      let self = this;
 
       return new PromiseEmitter(function (resolve, reject) {
         const defer = Promise.defer();
@@ -143,7 +143,7 @@ define(function (require) {
      * @return {Promise}
      */
     SourceAbstract.prototype.onError = function (handler) {
-      var self = this;
+      let self = this;
 
       return new PromiseEmitter(function (resolve, reject) {
         const defer = Promise.defer();
@@ -166,8 +166,8 @@ define(function (require) {
      * @async
      */
     SourceAbstract.prototype.fetch = function () {
-      var self = this;
-      var req = _.first(self._myStartableQueued());
+      let self = this;
+      let req = _.first(self._myStartableQueued());
 
       if (!req) {
         req = self._createRequest();
@@ -226,16 +226,16 @@ define(function (require) {
      * @resolved {Object|null} - the flat state of the SourceAbstract
      */
     SourceAbstract.prototype._flatten = function () {
-      var type = this._getType();
+      let type = this._getType();
 
       // the merged state of this dataSource and it's ancestors
-      var flatState = {};
+      let flatState = {};
 
       // function used to write each property from each state object in the chain to flat state
-      var root = this;
+      let root = this;
 
       // start the chain at this source
-      var current = this;
+      let current = this;
 
       // call the ittr and return it's promise
       return (function ittr() {
@@ -249,12 +249,12 @@ define(function (require) {
             });
           }
 
-          var prom = root._mergeProp(flatState, value, key);
+          let prom = root._mergeProp(flatState, value, key);
           return Promise.is(prom) ? prom : null;
         }))
         .then(function () {
           // move to this sources parent
-          var parent = current.getParent();
+          let parent = current.getParent();
           // keep calling until we reach the top parent
           if (parent) {
             current = parent;
@@ -265,7 +265,7 @@ define(function (require) {
       .then(function () {
         if (type === 'search') {
           // This is down here to prevent the circular dependency
-          var decorateQuery = Private(require('ui/courier/data_source/_decorate_query'));
+          let decorateQuery = Private(require('ui/courier/data_source/_decorate_query'));
 
           flatState.body = flatState.body || {};
 
@@ -279,7 +279,7 @@ define(function (require) {
           if (flatState.body.size === 0) {
             flatState.search_type = 'count';
           } else {
-            var computedFields = flatState.index.getComputedFields();
+            let computedFields = flatState.index.getComputedFields();
             flatState.body.fields = computedFields.fields;
             flatState.body.script_fields = flatState.body.script_fields || {};
             flatState.body.fielddata_fields = flatState.body.fielddata_fields || [];
@@ -297,7 +297,7 @@ define(function (require) {
            *                          through otherwise it will filter out
            * @returns {function}
            */
-          var filterNegate = function (reverse) {
+          let filterNegate = function (reverse) {
             return function (filter) {
               if (_.isUndefined(filter.meta) || _.isUndefined(filter.meta.negate)) return !reverse;
               return filter.meta && filter.meta.negate === reverse;
@@ -309,7 +309,7 @@ define(function (require) {
            * @param {object} filter The filter to clean
            * @returns {object}
            */
-          var cleanFilter = function (filter) {
+          let cleanFilter = function (filter) {
             return _.omit(filter, ['meta']);
           };
 
diff --git a/src/ui/public/courier/data_source/_decorate_query.js b/src/ui/public/courier/data_source/_decorate_query.js
index 45038fe0f4480..6a12ebe3a7dd0 100644
--- a/src/ui/public/courier/data_source/_decorate_query.js
+++ b/src/ui/public/courier/data_source/_decorate_query.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   return function DecorateQuery(config) {
     /**
      * Decorate queries with default parameters
@@ -7,7 +7,7 @@ define(function (require) {
      * @returns {object}
      */
     return function (query) {
-      var queryOptions = config.get('query:queryString:options');
+      let queryOptions = config.get('query:queryString:options');
 
       if (_.has(query, 'query_string.query')) {
         _.extend(query.query_string, queryOptions);
diff --git a/src/ui/public/courier/data_source/_doc_send_to_es.js b/src/ui/public/courier/data_source/_doc_send_to_es.js
index ea3d5f49b5f26..c01c46f6ffc37 100644
--- a/src/ui/public/courier/data_source/_doc_send_to_es.js
+++ b/src/ui/public/courier/data_source/_doc_send_to_es.js
@@ -1,10 +1,10 @@
 define(function (require) {
-  var _ = require('lodash');
-  var errors = require('ui/errors');
+  let _ = require('lodash');
+  let errors = require('ui/errors');
 
   return function (Promise, Private, es) {
-    var requestQueue = Private(require('ui/courier/_request_queue'));
-    var courierFetch = Private(require('ui/courier/fetch/fetch'));
+    let requestQueue = Private(require('ui/courier/_request_queue'));
+    let courierFetch = Private(require('ui/courier/fetch/fetch'));
 
     /**
      * Backend for doUpdate and doIndex
@@ -14,9 +14,9 @@ define(function (require) {
      * @param  {String} body - HTTP request body
      */
     return function (method, validateVersion, body, ignore) {
-      var doc = this;
+      let doc = this;
       // straight assignment will causes undefined values
-      var params = _.pick(this._state, ['id', 'type', 'index']);
+      let params = _.pick(this._state, ['id', 'type', 'index']);
       params.body = body;
       params.ignore = ignore || [409];
 
@@ -49,13 +49,13 @@ define(function (require) {
         // notify pending request for this same document that we have updates
         docFetchProm.then(function (fetchResp) {
           // use the key to compair sources
-          var key = doc._versionKey();
+          let key = doc._versionKey();
 
           // clear the queue and filter out the removed items, pushing the
           // unmatched ones back in.
-          var respondTo = requestQueue.splice(0).filter(function (req) {
-            var isDoc = req.source._getType() === 'doc';
-            var keyMatches = isDoc && req.source._versionKey() === key;
+          let respondTo = requestQueue.splice(0).filter(function (req) {
+            let isDoc = req.source._getType() === 'doc';
+            let keyMatches = isDoc && req.source._versionKey() === key;
 
             // put some request back into the queue
             if (!keyMatches) {
diff --git a/src/ui/public/courier/data_source/_normalize_sort_request.js b/src/ui/public/courier/data_source/_normalize_sort_request.js
index c5e38e2b42bfa..37313291e4548 100644
--- a/src/ui/public/courier/data_source/_normalize_sort_request.js
+++ b/src/ui/public/courier/data_source/_normalize_sort_request.js
@@ -1,7 +1,7 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   return function normalizeSortRequest(config) {
-    var defaultSortOptions = config.get('sort:options');
+    let defaultSortOptions = config.get('sort:options');
 
     /**
      * Decorate queries with default parameters
@@ -9,7 +9,7 @@ define(function (require) {
      * @returns {object}
      */
     return function (sortObject, indexPattern) {
-      var normalizedSort = [];
+      let normalizedSort = [];
 
       // [].concat({}) -> [{}], [].concat([{}]) -> [{}]
       return [].concat(sortObject).map(function (sortable) {
@@ -22,10 +22,10 @@ define(function (require) {
       { someField: "desc" } into { someField: { "order": "desc"}}
     */
     function normalize(sortable, indexPattern) {
-      var normalized = {};
-      var sortField = _.keys(sortable)[0];
-      var sortValue = sortable[sortField];
-      var indexField = indexPattern.fields.byName[sortField];
+      let normalized = {};
+      let sortField = _.keys(sortable)[0];
+      let sortValue = sortable[sortField];
+      let indexField = indexPattern.fields.byName[sortField];
 
       if (indexField && indexField.scripted && indexField.sortable) {
         let direction;
diff --git a/src/ui/public/courier/data_source/_root_search_source.js b/src/ui/public/courier/data_source/_root_search_source.js
index 1f676175c1560..fb68bef72d9fd 100644
--- a/src/ui/public/courier/data_source/_root_search_source.js
+++ b/src/ui/public/courier/data_source/_root_search_source.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function RootSearchSource(Private, $rootScope, timefilter, Notifier) {
-    var SearchSource = Private(require('ui/courier/data_source/search_source'));
+    let SearchSource = Private(require('ui/courier/data_source/search_source'));
 
-    var notify = new Notifier({ location: 'Root Search Source' });
+    let notify = new Notifier({ location: 'Root Search Source' });
 
-    var globalSource = new SearchSource();
+    let globalSource = new SearchSource();
     globalSource.inherits(false); // this is the final source, it has no parents
     globalSource.filter(function (globalSource) {
       // dynamic time filter will be called in the _flatten phase of things
@@ -34,7 +34,7 @@ define(function (require) {
 
       // walk the parent chain until we get to the global source or nothing
       // that's where we will attach to the globalSource
-      var literalRoot = source;
+      let literalRoot = source;
       while (literalRoot._parent && literalRoot._parent !== globalSource) {
         literalRoot = literalRoot._parent;
       }
diff --git a/src/ui/public/courier/data_source/doc_source.js b/src/ui/public/courier/data_source/doc_source.js
index f6f32eeddf286..6c60d87f97998 100644
--- a/src/ui/public/courier/data_source/doc_source.js
+++ b/src/ui/public/courier/data_source/doc_source.js
@@ -1,11 +1,11 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   return function DocSourceFactory(Private, Promise, es, sessionStorage) {
-    var sendToEs = Private(require('ui/courier/data_source/_doc_send_to_es'));
-    var SourceAbstract = Private(require('ui/courier/data_source/_abstract'));
-    var DocRequest = Private(require('ui/courier/fetch/request/doc'));
-    var docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
+    let sendToEs = Private(require('ui/courier/data_source/_doc_send_to_es'));
+    let SourceAbstract = Private(require('ui/courier/data_source/_abstract'));
+    let DocRequest = Private(require('ui/courier/fetch/request/doc'));
+    let docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
 
     _.class(DocSource).inherits(SourceAbstract);
     function DocSource(initialState) {
@@ -92,7 +92,7 @@ define(function (require) {
      * @return {string}
      */
     DocSource.prototype._versionKey = function () {
-      var state = this._state;
+      let state = this._state;
 
       if (!state.index || !state.type || !state.id) return;
       return 'DocVersion:' + (
@@ -118,10 +118,10 @@ define(function (require) {
      * @return {[type]} [description]
      */
     DocSource.prototype._getStoredVersion = function () {
-      var key = this._versionKey();
+      let key = this._versionKey();
       if (!key) return;
 
-      var v = sessionStorage.get(key);
+      let v = sessionStorage.get(key);
       this._version = v ? _.parseInt(v) : void 0;
       return this._version;
     };
@@ -134,7 +134,7 @@ define(function (require) {
     DocSource.prototype._storeVersion = function (version) {
       if (!version) return this._clearVersion();
 
-      var key = this._versionKey();
+      let key = this._versionKey();
       if (!key) return;
       this._version = version;
       sessionStorage.set(key, version);
@@ -144,7 +144,7 @@ define(function (require) {
      * Clears the stored version for a DocSource
      */
     DocSource.prototype._clearVersion = function () {
-      var key = this._versionKey();
+      let key = this._versionKey();
       if (!key) return;
       sessionStorage.remove(key);
     };
diff --git a/src/ui/public/courier/data_source/search_source.js b/src/ui/public/courier/data_source/search_source.js
index 6deaa47f23952..63aee24643725 100644
--- a/src/ui/public/courier/data_source/search_source.js
+++ b/src/ui/public/courier/data_source/search_source.js
@@ -1,12 +1,12 @@
 define(function (require) {
   return function SearchSourceFactory(Promise, Private) {
-    var _ = require('lodash');
-    var SourceAbstract = Private(require('ui/courier/data_source/_abstract'));
-    var SearchRequest = Private(require('ui/courier/fetch/request/search'));
-    var SegmentedRequest = Private(require('ui/courier/fetch/request/segmented'));
-    var searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
-    var normalizeSortRequest = Private(require('ui/courier/data_source/_normalize_sort_request'));
-    var rootSearchSource = require('ui/courier/data_source/_root_search_source');
+    let _ = require('lodash');
+    let SourceAbstract = Private(require('ui/courier/data_source/_abstract'));
+    let SearchRequest = Private(require('ui/courier/fetch/request/search'));
+    let SegmentedRequest = Private(require('ui/courier/fetch/request/segmented'));
+    let searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
+    let normalizeSortRequest = Private(require('ui/courier/data_source/_normalize_sort_request'));
+    let rootSearchSource = require('ui/courier/data_source/_root_search_source');
 
     _.class(SearchSource).inherits(SourceAbstract);
     function SearchSource(initialState) {
@@ -65,7 +65,7 @@ define(function (require) {
      * @return {undefined|searchSource}
      */
     SearchSource.prototype.getParent = function (onlyHardLinked) {
-      var self = this;
+      let self = this;
       if (self._parent === false) return;
       if (self._parent) return self._parent;
       return onlyHardLinked ? undefined : Private(rootSearchSource).get();
@@ -86,9 +86,9 @@ define(function (require) {
     };
 
     SearchSource.prototype.onBeginSegmentedFetch = function (initFunction) {
-      var self = this;
+      let self = this;
       return Promise.try(function addRequest() {
-        var req = new SegmentedRequest(self, Promise.defer(), initFunction);
+        let req = new SegmentedRequest(self, Promise.defer(), initFunction);
 
         // return promises created by the completion handler so that
         // errors will bubble properly
@@ -133,7 +133,7 @@ define(function (require) {
      */
     SearchSource.prototype._mergeProp = function (state, val, key) {
       if (typeof val === 'function') {
-        var source = this;
+        let source = this;
         return Promise.cast(val(this))
         .then(function (newVal) {
           return source._mergeProp(state, newVal, key);
diff --git a/src/ui/public/courier/fetch/_call_client.js b/src/ui/public/courier/fetch/_call_client.js
index 2f47ebad76b8f..75f24d891b82d 100644
--- a/src/ui/public/courier/fetch/_call_client.js
+++ b/src/ui/public/courier/fetch/_call_client.js
@@ -1,29 +1,29 @@
 define(function (require) {
   return function CourierFetchCallClient(Private, Promise, es, esShardTimeout, sessionId) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var isRequest = Private(require('ui/courier/fetch/_is_request'));
-    var mergeDuplicateRequests = Private(require('ui/courier/fetch/_merge_duplicate_requests'));
+    let isRequest = Private(require('ui/courier/fetch/_is_request'));
+    let mergeDuplicateRequests = Private(require('ui/courier/fetch/_merge_duplicate_requests'));
 
-    var ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
-    var DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
+    let ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
+    let DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
 
     function callClient(strategy, requests) {
       // merging docs can change status to DUPLICATE, capture new statuses
-      var statuses = mergeDuplicateRequests(requests);
+      let statuses = mergeDuplicateRequests(requests);
 
       // get the actual list of requests that we will be fetching
-      var executable = statuses.filter(isRequest);
-      var execCount = executable.length;
+      let executable = statuses.filter(isRequest);
+      let execCount = executable.length;
 
       if (!execCount) return Promise.resolve([]);
 
       // resolved by respond()
       let esPromise;
-      var defer = Promise.defer();
+      let defer = Promise.defer();
 
       // for each respond with either the response or ABORTED
-      var respond = function (responses) {
+      let respond = function (responses) {
         responses = responses || [];
         return Promise.map(requests, function (req, i) {
           switch (statuses[i]) {
@@ -43,7 +43,7 @@ define(function (require) {
 
 
       // handle a request being aborted while being fetched
-      var requestWasAborted = Promise.method(function (req, i) {
+      let requestWasAborted = Promise.method(function (req, i) {
         if (statuses[i] === ABORTED) {
           defer.reject(new Error('Request was aborted twice?'));
         }
diff --git a/src/ui/public/courier/fetch/_call_response_handlers.js b/src/ui/public/courier/fetch/_call_response_handlers.js
index 15fcd8bf9cf8e..0e75a13742e6a 100644
--- a/src/ui/public/courier/fetch/_call_response_handlers.js
+++ b/src/ui/public/courier/fetch/_call_response_handlers.js
@@ -1,12 +1,12 @@
 define(function (require) {
   return function CourierFetchCallResponseHandlers(Private, Promise) {
-    var ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
-    var INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
-    var notify = Private(require('ui/courier/fetch/_notifier'));
+    let ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
+    let INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
+    let notify = Private(require('ui/courier/fetch/_notifier'));
 
-    var SearchTimeout = require('ui/errors').SearchTimeout;
-    var RequestFailure = require('ui/errors').RequestFailure;
-    var ShardFailure = require('ui/errors').ShardFailure;
+    let SearchTimeout = require('ui/errors').SearchTimeout;
+    let RequestFailure = require('ui/errors').RequestFailure;
+    let ShardFailure = require('ui/errors').ShardFailure;
 
     function callResponseHandlers(requests, responses) {
       return Promise.map(requests, function (req, i) {
@@ -14,7 +14,7 @@ define(function (require) {
           return ABORTED;
         }
 
-        var resp = responses[i];
+        let resp = responses[i];
 
         if (resp.timed_out) {
           notify.warning(new SearchTimeout());
diff --git a/src/ui/public/courier/fetch/_continue_incomplete.js b/src/ui/public/courier/fetch/_continue_incomplete.js
index 45f911c691527..30b3853e2b578 100644
--- a/src/ui/public/courier/fetch/_continue_incomplete.js
+++ b/src/ui/public/courier/fetch/_continue_incomplete.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function CourierFetchContinueIncompleteRequests(Private) {
-    var INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
+    let INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
 
     function continueIncompleteRequests(strategy, requests, responses, fetchWithStrategy) {
-      var incomplete = [];
+      let incomplete = [];
 
       responses.forEach(function (resp, i) {
         if (resp === INCOMPLETE) {
diff --git a/src/ui/public/courier/fetch/_fetch_these.js b/src/ui/public/courier/fetch/_fetch_these.js
index 7b96dadae4689..2858cad846ed4 100644
--- a/src/ui/public/courier/fetch/_fetch_these.js
+++ b/src/ui/public/courier/fetch/_fetch_these.js
@@ -1,16 +1,16 @@
 define(function (require) {
   return function FetchTheseProvider(Private, Promise) {
-    var notify = Private(require('ui/courier/fetch/_notifier'));
-    var forEachStrategy = Private(require('ui/courier/fetch/_for_each_strategy'));
+    let notify = Private(require('ui/courier/fetch/_notifier'));
+    let forEachStrategy = Private(require('ui/courier/fetch/_for_each_strategy'));
 
     // core tasks
-    var callClient = Private(require('ui/courier/fetch/_call_client'));
-    var callResponseHandlers = Private(require('ui/courier/fetch/_call_response_handlers'));
-    var continueIncomplete = Private(require('ui/courier/fetch/_continue_incomplete'));
+    let callClient = Private(require('ui/courier/fetch/_call_client'));
+    let callResponseHandlers = Private(require('ui/courier/fetch/_call_response_handlers'));
+    let continueIncomplete = Private(require('ui/courier/fetch/_continue_incomplete'));
 
-    var ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
-    var DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
-    var INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
+    let ABORTED = Private(require('ui/courier/fetch/_req_status')).ABORTED;
+    let DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
+    let INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
 
     function fetchThese(requests) {
       return forEachStrategy(requests, function (strategy, reqsForStrategy) {
@@ -64,7 +64,7 @@ define(function (require) {
         }
 
         return new Promise(function (resolve) {
-          var action = req.started ? req.continue : req.start;
+          let action = req.started ? req.continue : req.start;
           resolve(action.call(req));
         })
         .catch(err => req.handleFailure(err));
diff --git a/src/ui/public/courier/fetch/_for_each_strategy.js b/src/ui/public/courier/fetch/_for_each_strategy.js
index cc13fe2381249..269da403f09fc 100644
--- a/src/ui/public/courier/fetch/_for_each_strategy.js
+++ b/src/ui/public/courier/fetch/_for_each_strategy.js
@@ -1,14 +1,14 @@
 define(function (require) {
   return function FetchForEachRequestStrategy(Private, Promise) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     function forEachStrategy(requests, block) {
       block = Promise.method(block);
-      var sets = [];
+      let sets = [];
 
       requests.forEach(function (req) {
-        var strategy = req.strategy;
-        var set = _.find(sets, { 0: strategy });
+        let strategy = req.strategy;
+        let set = _.find(sets, { 0: strategy });
         if (set) set[1].push(req);
         else sets.push([strategy, [req]]);
       });
diff --git a/src/ui/public/courier/fetch/_is_request.js b/src/ui/public/courier/fetch/_is_request.js
index 4a0eab4019cfa..64c34eeec85b9 100644
--- a/src/ui/public/courier/fetch/_is_request.js
+++ b/src/ui/public/courier/fetch/_is_request.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function CourierFetchIsRequestProvider(Private) {
-    var AbstractRequest = Private(require('ui/courier/fetch/request/request'));
+    let AbstractRequest = Private(require('ui/courier/fetch/request/request'));
 
     return function isRequest(obj) {
       return obj instanceof AbstractRequest;
diff --git a/src/ui/public/courier/fetch/_merge_duplicate_requests.js b/src/ui/public/courier/fetch/_merge_duplicate_requests.js
index fb79e6bf6148d..b1d9237032f77 100644
--- a/src/ui/public/courier/fetch/_merge_duplicate_requests.js
+++ b/src/ui/public/courier/fetch/_merge_duplicate_requests.js
@@ -1,15 +1,15 @@
 define(function (require) {
   return function FetchMergeDuplicateRequests(Private) {
-    var isRequest = Private(require('ui/courier/fetch/_is_request'));
-    var DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
+    let isRequest = Private(require('ui/courier/fetch/_is_request'));
+    let DUPLICATE = Private(require('ui/courier/fetch/_req_status')).DUPLICATE;
 
     function mergeDuplicateRequests(requests) {
       // dedupe requests
-      var index = {};
+      let index = {};
       return requests.map(function (req) {
         if (!isRequest(req)) return req;
 
-        var iid = req.source._instanceid;
+        let iid = req.source._instanceid;
         if (!index[iid]) {
           // this request is unique so far
           index[iid] = req;
diff --git a/src/ui/public/courier/fetch/fetch.js b/src/ui/public/courier/fetch/fetch.js
index adf1871bb4253..e7095c49b8fce 100644
--- a/src/ui/public/courier/fetch/fetch.js
+++ b/src/ui/public/courier/fetch/fetch.js
@@ -1,15 +1,15 @@
 define(function (require) {
   return function fetchService(Private, Promise) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var requestQueue = Private(require('ui/courier/_request_queue'));
-    var fetchThese = Private(require('ui/courier/fetch/_fetch_these'));
+    let requestQueue = Private(require('ui/courier/_request_queue'));
+    let fetchThese = Private(require('ui/courier/fetch/_fetch_these'));
 
-    var callResponseHandlers = Private(require('ui/courier/fetch/_call_response_handlers'));
-    var INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
+    let callResponseHandlers = Private(require('ui/courier/fetch/_call_response_handlers'));
+    let INCOMPLETE = Private(require('ui/courier/fetch/_req_status')).INCOMPLETE;
 
     function fetchQueued(strategy) {
-      var requests = requestQueue.getStartable(strategy);
+      let requests = requestQueue.getStartable(strategy);
       if (!requests.length) return Promise.resolve();
       else return fetchThese(requests);
     }
@@ -17,7 +17,7 @@ define(function (require) {
     this.fetchQueued = fetchQueued;
 
     function fetchASource(source, strategy) {
-      var defer = Promise.defer();
+      let defer = Promise.defer();
 
       fetchThese([
         source._createRequest(defer)
diff --git a/src/ui/public/courier/fetch/request/_error_handler.js b/src/ui/public/courier/fetch/request/_error_handler.js
index b4f8deba1823d..220d651250600 100644
--- a/src/ui/public/courier/fetch/request/_error_handler.js
+++ b/src/ui/public/courier/fetch/request/_error_handler.js
@@ -1,13 +1,13 @@
 define(function (require) {
   return function RequestErrorHandlerFactory(Private, Notifier) {
-    var errHandlers = Private(require('ui/courier/_error_handlers'));
+    let errHandlers = Private(require('ui/courier/_error_handlers'));
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Courier Fetch Error'
     });
 
     function handleError(req, error) {
-      var myHandlers = [];
+      let myHandlers = [];
 
       errHandlers.splice(0).forEach(function (handler) {
         (handler.source === req.source ? myHandlers : errHandlers).push(handler);
diff --git a/src/ui/public/courier/fetch/request/_segmented_handle.js b/src/ui/public/courier/fetch/request/_segmented_handle.js
index ad46cd350c4eb..e83c6858e5760 100644
--- a/src/ui/public/courier/fetch/request/_segmented_handle.js
+++ b/src/ui/public/courier/fetch/request/_segmented_handle.js
@@ -1,7 +1,7 @@
 define(function (require) {
   return function CourierSegmentedReqHandle(Private) {
-    var _ = require('lodash');
-    var Events = Private(require('ui/events'));
+    let _ = require('lodash');
+    let Events = Private(require('ui/events'));
 
 
     /**
diff --git a/src/ui/public/courier/fetch/request/doc.js b/src/ui/public/courier/fetch/request/doc.js
index b135fc2366ed2..487b570d390b9 100644
--- a/src/ui/public/courier/fetch/request/doc.js
+++ b/src/ui/public/courier/fetch/request/doc.js
@@ -1,9 +1,9 @@
 define(function (require) {
   return function DocRequestProvider(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
-    var AbstractRequest = Private(require('ui/courier/fetch/request/request'));
+    let docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
+    let AbstractRequest = Private(require('ui/courier/fetch/request/request'));
 
     _.class(DocRequest).inherits(AbstractRequest);
     function DocRequest(source, defer) {
@@ -14,15 +14,15 @@ define(function (require) {
     }
 
     DocRequest.prototype.canStart = function () {
-      var parent = DocRequest.Super.prototype.canStart.call(this);
+      let parent = DocRequest.Super.prototype.canStart.call(this);
       if (!parent) return false;
 
-      var version = this.source._version;
-      var storedVersion = this.source._getStoredVersion();
+      let version = this.source._version;
+      let storedVersion = this.source._getStoredVersion();
 
       // conditions that equal "fetch This DOC!"
-      var unknown = !version && !storedVersion;
-      var mismatch = version !== storedVersion;
+      let unknown = !version && !storedVersion;
+      let mismatch = version !== storedVersion;
 
       return Boolean(mismatch || (unknown && !this.started));
     };
diff --git a/src/ui/public/courier/fetch/request/request.js b/src/ui/public/courier/fetch/request/request.js
index 30d72080fea0e..0173803875234 100644
--- a/src/ui/public/courier/fetch/request/request.js
+++ b/src/ui/public/courier/fetch/request/request.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function AbstractReqProvider(Private, Promise) {
-    var _ = require('lodash');
-    var moment = require('moment');
-    var errors = require('ui/errors');
-    var requestQueue = Private(require('ui/courier/_request_queue'));
-    var requestErrorHandler = Private(require('ui/courier/fetch/request/_error_handler'));
+    let _ = require('lodash');
+    let moment = require('moment');
+    let errors = require('ui/errors');
+    let requestQueue = Private(require('ui/courier/_request_queue'));
+    let requestErrorHandler = Private(require('ui/courier/fetch/request/_error_handler'));
 
     function AbstractReq(source, defer) {
       if (!(this instanceof AbstractReq) || !this.constructor || this.constructor === AbstractReq) {
@@ -29,7 +29,7 @@ define(function (require) {
       this.started = true;
       this.moment = moment();
 
-      var source = this.source;
+      let source = this.source;
       if (source.activeFetchCount) {
         source.activeFetchCount += 1;
       } else {
@@ -72,7 +72,7 @@ define(function (require) {
     };
 
     AbstractReq.prototype.retry = function () {
-      var clone = this.clone();
+      let clone = this.clone();
       this.abort();
       return clone;
     };
diff --git a/src/ui/public/courier/fetch/request/search.js b/src/ui/public/courier/fetch/request/search.js
index ad2eca53e9af0..f13c6df0bbb39 100644
--- a/src/ui/public/courier/fetch/request/search.js
+++ b/src/ui/public/courier/fetch/request/search.js
@@ -1,12 +1,12 @@
 define(function (require) {
   return function SearchReqProvider(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
-    var searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
-    var AbstractRequest = Private(require('ui/courier/fetch/request/request'));
+    let searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
+    let AbstractRequest = Private(require('ui/courier/fetch/request/request'));
 
     _.class(SearchReq).inherits(AbstractRequest);
-    var Super = SearchReq.Super;
+    let Super = SearchReq.Super;
     function SearchReq(source, defer) {
       Super.call(this, source, defer);
 
diff --git a/src/ui/public/courier/fetch/request/segmented.js b/src/ui/public/courier/fetch/request/segmented.js
index f7741b0ba584a..142da71ebf2c8 100644
--- a/src/ui/public/courier/fetch/request/segmented.js
+++ b/src/ui/public/courier/fetch/request/segmented.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function CourierSegmentedReqProvider(es, Private, Promise, Notifier, timefilter, config) {
-    var _ = require('lodash');
-    var isNumber = require('lodash').isNumber;
-    var SearchReq = Private(require('ui/courier/fetch/request/search'));
-    var SegmentedHandle = Private(require('ui/courier/fetch/request/_segmented_handle'));
+    let _ = require('lodash');
+    let isNumber = require('lodash').isNumber;
+    let SearchReq = Private(require('ui/courier/fetch/request/search'));
+    let SegmentedHandle = Private(require('ui/courier/fetch/request/_segmented_handle'));
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Segmented Fetch'
     });
 
@@ -37,7 +37,7 @@ define(function (require) {
      *********/
 
     SegmentedReq.prototype.start = function () {
-      var self = this;
+      let self = this;
 
       SearchReq.prototype.start.call(this);
 
@@ -74,20 +74,20 @@ define(function (require) {
     };
 
     SegmentedReq.prototype.getFetchParams = function () {
-      var self = this;
+      let self = this;
 
       return self._getFlattenedSource().then(function (flatSource) {
-        var params = _.cloneDeep(flatSource);
+        let params = _.cloneDeep(flatSource);
 
         // calculate the number of indices to fetch in this request in order to prevent
         // more than self._maxSegments requests. We use Math.max(1, n) to ensure that each request
         // has at least one index pattern, and Math.floor() to make sure that if the
         // number of indices does not round out evenly the extra index is tacked onto the last
         // request, making sure the first request returns faster.
-        var remainingSegments = self._maxSegments - self._segments.length;
-        var indexCount = Math.max(1, Math.floor(self._queue.length / remainingSegments));
+        let remainingSegments = self._maxSegments - self._segments.length;
+        let indexCount = Math.max(1, Math.floor(self._queue.length / remainingSegments));
 
-        var indices = self._active = self._queue.splice(0, indexCount);
+        let indices = self._active = self._queue.splice(0, indexCount);
         params.index = _.pluck(indices, 'index');
 
         if (isNumber(self._desiredSize)) {
@@ -112,8 +112,8 @@ define(function (require) {
     };
 
     SegmentedReq.prototype.isIncomplete = function () {
-      var queueNotCreated = !this._queueCreated;
-      var queueNotEmpty = this._queue.length > 0;
+      let queueNotCreated = !this._queueCreated;
+      let queueNotEmpty = this._queue.length > 0;
       return queueNotCreated || queueNotEmpty;
     };
 
@@ -181,9 +181,9 @@ define(function (require) {
     };
 
     SegmentedReq.prototype._createQueue = function () {
-      var self = this;
-      var timeBounds = timefilter.getBounds();
-      var indexPattern = self.source.get('index');
+      let self = this;
+      let timeBounds = timefilter.getBounds();
+      let indexPattern = self.source.get('index');
       self._queueCreated = false;
 
       return indexPattern.toDetailedIndexList(timeBounds.min, timeBounds.max, self._direction)
@@ -211,14 +211,14 @@ define(function (require) {
     };
 
     SegmentedReq.prototype._consumeSegment = function (seg) {
-      var index = this._active;
+      let index = this._active;
       this._complete.push(index);
       if (!seg) return; // segment was ignored/filtered, don't store it
 
-      var hadHits = _.get(this._mergedResp, 'hits.hits.length') > 0;
-      var gotHits = _.get(seg, 'hits.hits.length') > 0;
-      var firstHits = !hadHits && gotHits;
-      var haveHits = hadHits || gotHits;
+      let hadHits = _.get(this._mergedResp, 'hits.hits.length') > 0;
+      let gotHits = _.get(seg, 'hits.hits.length') > 0;
+      let firstHits = !hadHits && gotHits;
+      let haveHits = hadHits || gotHits;
 
       this._mergeSegment(seg);
       this.resp = _.omit(this._mergedResp, '_bucketIndex');
@@ -229,9 +229,9 @@ define(function (require) {
     };
 
     SegmentedReq.prototype._mergeHits = function (hits) {
-      var mergedHits = this._mergedResp.hits.hits;
-      var desiredSize = this._desiredSize;
-      var sortFn = this._sortFn;
+      let mergedHits = this._mergedResp.hits.hits;
+      let desiredSize = this._desiredSize;
+      let sortFn = this._sortFn;
 
       _.pushAll(hits, mergedHits);
 
@@ -247,7 +247,7 @@ define(function (require) {
     };
 
     SegmentedReq.prototype._mergeSegment = notify.timed('merge response segment', function (seg) {
-      var merged = this._mergedResp;
+      let merged = this._mergedResp;
 
       this._segments.push(seg);
 
@@ -277,7 +277,7 @@ define(function (require) {
         }
 
         seg.aggregations[aggKey].buckets.forEach(function (bucket) {
-          var mbucket = merged._bucketIndex[bucket.key];
+          let mbucket = merged._bucketIndex[bucket.key];
           if (mbucket) {
             mbucket.doc_count += bucket.doc_count;
             return;
@@ -291,10 +291,10 @@ define(function (require) {
 
     SegmentedReq.prototype._detectHitsWindow = function (hits) {
       hits = hits || [];
-      var indexPattern = this.source.get('index');
-      var desiredSize = this._desiredSize;
+      let indexPattern = this.source.get('index');
+      let desiredSize = this._desiredSize;
 
-      var size = _.size(hits);
+      let size = _.size(hits);
       if (!isNumber(desiredSize) || size < desiredSize) {
         this._hitWindow = {
           size: size,
@@ -308,8 +308,8 @@ define(function (require) {
       let max;
 
       hits.forEach(function (deepHit) {
-        var hit = indexPattern.flattenHit(deepHit);
-        var time = hit[indexPattern.timeFieldName];
+        let hit = indexPattern.flattenHit(deepHit);
+        let time = hit[indexPattern.timeFieldName];
         if (min == null || time < min) min = time;
         if (max == null || time > max) max = time;
       });
@@ -318,8 +318,8 @@ define(function (require) {
     };
 
     SegmentedReq.prototype._pickSizeForIndices = function (indices) {
-      var hitWindow = this._hitWindow;
-      var desiredSize = this._desiredSize;
+      let hitWindow = this._hitWindow;
+      let desiredSize = this._desiredSize;
 
       if (!isNumber(desiredSize)) return null;
       // we don't have any hits yet, get us more info!
@@ -327,7 +327,7 @@ define(function (require) {
       // the order of documents isn't important, just get us more
       if (!this._sortFn) return Math.max(desiredSize - hitWindow.size, 0);
       // if all of the documents in every index fall outside of our current doc set, we can ignore them.
-      var someOverlap = indices.some(function (index) {
+      let someOverlap = indices.some(function (index) {
         return index.min <= hitWindow.max && hitWindow.min <= index.max;
       });
 
diff --git a/src/ui/public/courier/fetch/strategy/search.js b/src/ui/public/courier/fetch/strategy/search.js
index 6616c2931e4c5..434ad86da7ddf 100644
--- a/src/ui/public/courier/fetch/strategy/search.js
+++ b/src/ui/public/courier/fetch/strategy/search.js
@@ -1,8 +1,8 @@
 define(function (require) {
   return function FetchStrategyForSearch(Private, Promise, timefilter) {
-    var _ = require('lodash');
-    var angular = require('angular');
-    var toJson = require('ui/utils/aggressive_parse').toJson;
+    let _ = require('lodash');
+    let angular = require('angular');
+    let toJson = require('ui/utils/aggressive_parse').toJson;
 
     return {
       clientMethod: 'msearch',
@@ -21,7 +21,7 @@ define(function (require) {
               return indexList;
             }
 
-            var timeBounds = timefilter.getBounds();
+            let timeBounds = timefilter.getBounds();
             return indexList.toIndexList(timeBounds.min, timeBounds.max);
           })
           .then(function (indexList) {
diff --git a/src/ui/public/courier/looper/_looper.js b/src/ui/public/courier/looper/_looper.js
index 8a980ad10ef3d..0df02c698809a 100644
--- a/src/ui/public/courier/looper/_looper.js
+++ b/src/ui/public/courier/looper/_looper.js
@@ -1,7 +1,7 @@
 define(function (require) {
   return function LooperFactory($timeout, Notifier, Promise) {
-    var _ = require('lodash');
-    var notify = new Notifier();
+    let _ = require('lodash');
+    let notify = new Notifier();
 
     function Looper(ms, fn) {
       this._fn = fn;
@@ -127,7 +127,7 @@ define(function (require) {
      * @return {undefined}
      */
     Looper.prototype._loopTheLoop = function () {
-      var self = this;
+      let self = this;
 
       if (self.active) {
         self.onHastyLoop();
diff --git a/src/ui/public/courier/looper/doc.js b/src/ui/public/courier/looper/doc.js
index 1bb9bf23ae5e7..1ecbc838d4172 100644
--- a/src/ui/public/courier/looper/doc.js
+++ b/src/ui/public/courier/looper/doc.js
@@ -1,14 +1,14 @@
 define(function (require) {
   return function DocLooperService(Private) {
-    var fetch = Private(require('ui/courier/fetch/fetch'));
-    var Looper = Private(require('ui/courier/looper/_looper'));
-    var docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
+    let fetch = Private(require('ui/courier/fetch/fetch'));
+    let Looper = Private(require('ui/courier/looper/_looper'));
+    let docStrategy = Private(require('ui/courier/fetch/strategy/doc'));
 
     /**
      * The Looper which will manage the doc fetch interval
      * @type {Looper}
      */
-    var docLooper = new Looper(1500, function () {
+    let docLooper = new Looper(1500, function () {
       fetch.fetchQueued(docStrategy);
     });
 
diff --git a/src/ui/public/courier/looper/search.js b/src/ui/public/courier/looper/search.js
index 11ddc5f2fa1b2..41cc8edfb38ac 100644
--- a/src/ui/public/courier/looper/search.js
+++ b/src/ui/public/courier/looper/search.js
@@ -1,17 +1,17 @@
 define(function (require) {
   return function SearchLooperService(Private, Promise, Notifier, $rootScope) {
-    var fetch = Private(require('ui/courier/fetch/fetch'));
-    var searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
-    var requestQueue = Private(require('ui/courier/_request_queue'));
+    let fetch = Private(require('ui/courier/fetch/fetch'));
+    let searchStrategy = Private(require('ui/courier/fetch/strategy/search'));
+    let requestQueue = Private(require('ui/courier/_request_queue'));
 
-    var Looper = Private(require('ui/courier/looper/_looper'));
-    var notif = new Notifier({ location: 'Search Looper' });
+    let Looper = Private(require('ui/courier/looper/_looper'));
+    let notif = new Notifier({ location: 'Search Looper' });
 
     /**
      * The Looper which will manage the doc fetch interval
      * @type {Looper}
      */
-    var searchLooper = new Looper(null, function () {
+    let searchLooper = new Looper(null, function () {
       $rootScope.$broadcast('courier:searchRefresh');
       return fetch.these(
         requestQueue.getInactive(searchStrategy)
diff --git a/src/ui/public/courier/saved_object/saved_object.js b/src/ui/public/courier/saved_object/saved_object.js
index 3d48bdf4a3700..077ba04845b53 100644
--- a/src/ui/public/courier/saved_object/saved_object.js
+++ b/src/ui/public/courier/saved_object/saved_object.js
@@ -1,42 +1,42 @@
 define(function (require) {
   return function SavedObjectFactory(es, kbnIndex, Promise, Private, Notifier, safeConfirm, indexPatterns) {
-    var angular = require('angular');
-    var errors = require('ui/errors');
-    var _ = require('lodash');
-    var slugifyId = require('ui/utils/slugify_id');
+    let angular = require('angular');
+    let errors = require('ui/errors');
+    let _ = require('lodash');
+    let slugifyId = require('ui/utils/slugify_id');
 
-    var DocSource = Private(require('ui/courier/data_source/doc_source'));
-    var SearchSource = Private(require('ui/courier/data_source/search_source'));
-    var mappingSetup = Private(require('ui/utils/mapping_setup'));
+    let DocSource = Private(require('ui/courier/data_source/doc_source'));
+    let SearchSource = Private(require('ui/courier/data_source/search_source'));
+    let mappingSetup = Private(require('ui/utils/mapping_setup'));
 
     function SavedObject(config) {
       if (!_.isObject(config)) config = {};
 
       // save an easy reference to this
-      var self = this;
+      let self = this;
 
       /************
        * Initialize config vars
        ************/
       // the doc which is used to store this object
-      var docSource = new DocSource();
+      let docSource = new DocSource();
 
       // type name for this object, used as the ES-type
-      var type = config.type;
+      let type = config.type;
 
       // Create a notifier for sending alerts
-      var notify = new Notifier({
+      let notify = new Notifier({
         location: 'Saved ' + type
       });
 
       // mapping definition for the fields that this object will expose
-      var mapping = mappingSetup.expandShorthand(config.mapping);
+      let mapping = mappingSetup.expandShorthand(config.mapping);
 
       // default field values, assigned when the source is loaded
-      var defaults = config.defaults || {};
+      let defaults = config.defaults || {};
 
-      var afterESResp = config.afterESResp || _.noop;
-      var customInit = config.init || _.noop;
+      let afterESResp = config.afterESResp || _.noop;
+      let customInit = config.init || _.noop;
 
       // optional search source which this object configures
       self.searchSource = config.searchSource && new SearchSource();
@@ -108,7 +108,7 @@ define(function (require) {
 
         if (resp.found != null && !resp.found) throw new errors.SavedObjectNotFound(type, self.id);
 
-        var meta = resp._source.kibanaSavedObjectMeta || {};
+        let meta = resp._source.kibanaSavedObjectMeta || {};
         delete resp._source.kibanaSavedObjectMeta;
 
         if (!config.indexPattern && self._source.indexPattern) {
@@ -153,8 +153,8 @@ define(function (require) {
           state = {};
         }
 
-        var oldState = self.searchSource.toJSON();
-        var fnProps = _.transform(oldState, function (dynamic, val, name) {
+        let oldState = self.searchSource.toJSON();
+        let fnProps = _.transform(oldState, function (dynamic, val, name) {
           if (_.isFunction(val)) dynamic[name] = val;
         }, {});
 
@@ -171,7 +171,7 @@ define(function (require) {
         return Promise.try(function () {
           if (self.searchSource) {
 
-            var index = config.indexPattern || self.searchSource.getOwn('index');
+            let index = config.indexPattern || self.searchSource.getOwn('index');
             if (!index) return;
             if (config.clearSavedIndexPattern) {
               self.searchSource.set('index', undefined);
@@ -195,7 +195,7 @@ define(function (require) {
        * @return {Object}
        */
       self.serialize = function () {
-        var body = {};
+        let body = {};
 
         _.forOwn(mapping, function (fieldMapping, fieldName) {
           if (self[fieldName] != null) {
@@ -222,7 +222,7 @@ define(function (require) {
        */
       self.save = function () {
 
-        var body = self.serialize();
+        let body = self.serialize();
 
         // Slugify the object id
         self.id = slugifyId(self.id);
@@ -235,7 +235,7 @@ define(function (require) {
       };
 
       self.saveSource = function (source) {
-        var finish = function (id) {
+        let finish = function (id) {
           self.id = id;
           return es.indices.refresh({
             index: kbnIndex
@@ -250,7 +250,7 @@ define(function (require) {
         .catch(function (err) {
           // record exists, confirm overwriting
           if (_.get(err, 'origError.status') === 409) {
-            var confirmMessage = 'Are you sure you want to overwrite ' + self.title + '?';
+            let confirmMessage = 'Are you sure you want to overwrite ' + self.title + '?';
 
             return safeConfirm(confirmMessage).then(
               function () {
diff --git a/src/ui/public/debounce/debounce.js b/src/ui/public/debounce/debounce.js
index 7cf725f6bf023..a5b375099aa6c 100644
--- a/src/ui/public/debounce/debounce.js
+++ b/src/ui/public/debounce/debounce.js
@@ -2,8 +2,8 @@
 // borrowed heavily from https://github.com/shahata/angular-debounce
 
 define(function (require) {
-  var _ = require('lodash');
-  var module = require('ui/modules').get('kibana');
+  let _ = require('lodash');
+  let module = require('ui/modules').get('kibana');
 
   module.service('debounce', ['$timeout', function ($timeout) {
     return function (func, wait, options) {
@@ -20,14 +20,14 @@ define(function (require) {
         self = this;
         args = arguments;
 
-        var later = function () {
+        let later = function () {
           timeout = null;
           if (!options.leading || options.trailing) {
             result = func.apply(self, args);
           }
         };
 
-        var callNow = options.leading && !timeout;
+        let callNow = options.leading && !timeout;
 
         if (timeout) {
           $timeout.cancel(timeout);
diff --git a/src/ui/public/directives/auto_select_if_only_one.js b/src/ui/public/directives/auto_select_if_only_one.js
index f0b62d32c96ff..0e46737d41284 100644
--- a/src/ui/public/directives/auto_select_if_only_one.js
+++ b/src/ui/public/directives/auto_select_if_only_one.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
+  let module = require('ui/modules').get('kibana');
 
   module.directive('autoSelectIfOnlyOne', function ($parse) {
     return {
@@ -7,7 +7,7 @@ define(function (require) {
       require: 'ngModel',
       link: function (scope, element, attributes, ngModelCtrl) {
         attributes.$observe('autoSelectIfOnlyOne', function (result) {
-          var options = $parse(result)(scope);
+          let options = $parse(result)(scope);
           if (options && options.length === 1) {
             ngModelCtrl.$setViewValue(options[0]);
             ngModelCtrl.$render();
diff --git a/src/ui/public/directives/click_focus.js b/src/ui/public/directives/click_focus.js
index d996664e069f4..e005afd2cf97b 100644
--- a/src/ui/public/directives/click_focus.js
+++ b/src/ui/public/directives/click_focus.js
@@ -1,7 +1,7 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var _ = require('lodash');
-  var $ = require('jquery');
+  let module = require('ui/modules').get('kibana');
+  let _ = require('lodash');
+  let $ = require('jquery');
 
   module.directive('clickFocus', function () {
     return {
@@ -11,7 +11,7 @@ define(function (require) {
       restrict: 'A',
       link: function ($scope, $elem) {
         function handler() {
-          var focusElem = $.find('input[name=' + $scope.clickFocus + ']');
+          let focusElem = $.find('input[name=' + $scope.clickFocus + ']');
           if (focusElem[0]) focusElem[0].focus();
         }
 
diff --git a/src/ui/public/directives/config.js b/src/ui/public/directives/config.js
index a8f69b28ca5e7..44ae5a102a3e7 100644
--- a/src/ui/public/directives/config.js
+++ b/src/ui/public/directives/config.js
@@ -1,9 +1,9 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
   require('ui/watch_multi');
-  var ConfigTemplate = require('ui/ConfigTemplate');
-  var angular = require('angular');
-  var module = require('ui/modules').get('kibana');
+  let ConfigTemplate = require('ui/ConfigTemplate');
+  let angular = require('angular');
+  let module = require('ui/modules').get('kibana');
 
   require('ui/directives/input_focus');
 
@@ -26,13 +26,13 @@ define(function (require) {
         configObject: '='
       },
       link: function ($scope, element, attr) {
-        var tmpScope = $scope.$new();
+        let tmpScope = $scope.$new();
 
         $scope.$watch('configObject', function (newVal) {
           $scope[attr.configObject] = $scope.configObject;
         });
 
-        var wrapTmpl = function (tmpl) {
+        let wrapTmpl = function (tmpl) {
           if ($scope.configSubmit) {
             return '<form role="form" class="container-fluid" ng-submit="configSubmit()">' + tmpl + '</form>';
           } else {
@@ -44,7 +44,7 @@ define(function (require) {
           'configSubmit',
           'configTemplate.current || configTemplate'
         ], function () {
-          var tmpl = $scope.configTemplate;
+          let tmpl = $scope.configTemplate;
           if (tmpl instanceof ConfigTemplate) {
             tmpl = tmpl.toString();
           }
@@ -52,7 +52,7 @@ define(function (require) {
           tmpScope.$destroy();
           tmpScope = $scope.$new();
 
-          var html = '';
+          let html = '';
           if (tmpl) {
             html = $compile('' +
               '<div class="config" ng-show="configTemplate">' +
diff --git a/src/ui/public/directives/confirm_click.js b/src/ui/public/directives/confirm_click.js
index c4f10462948de..b2e710740cf09 100644
--- a/src/ui/public/directives/confirm_click.js
+++ b/src/ui/public/directives/confirm_click.js
@@ -6,9 +6,9 @@ define(function (require) {
       restrict: 'A',
       link: function ($scope, $elem, attrs) {
         $elem.bind('click', function () {
-          var message = attrs.confirmation || 'Are you sure?';
+          let message = attrs.confirmation || 'Are you sure?';
           if (window.confirm(message)) { // eslint-disable-line no-alert
-            var action = attrs.confirmClick;
+            let action = attrs.confirmClick;
             if (action) {
               $scope.$apply($scope.$eval(action));
             }
diff --git a/src/ui/public/directives/css_truncate.js b/src/ui/public/directives/css_truncate.js
index 1b6afcdd2d07e..13c38b7c11b60 100644
--- a/src/ui/public/directives/css_truncate.js
+++ b/src/ui/public/directives/css_truncate.js
@@ -1,7 +1,7 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var $ = require('jquery');
-  var _ = require('lodash');
+  let module = require('ui/modules').get('kibana');
+  let $ = require('jquery');
+  let _ = require('lodash');
 
   module.directive('cssTruncate', function ($timeout) {
     return {
diff --git a/src/ui/public/directives/field_name.js b/src/ui/public/directives/field_name.js
index 21bf398c825f1..b6fa45fb0e447 100644
--- a/src/ui/public/directives/field_name.js
+++ b/src/ui/public/directives/field_name.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
+  let module = require('ui/modules').get('kibana');
   require('ui/filters/short_dots');
 
   module.directive('fieldName', function ($compile, $rootScope, $filter) {
@@ -12,7 +12,7 @@ define(function (require) {
       },
       link: function ($scope, $el) {
 
-        var typeIcon = function (fieldType) {
+        let typeIcon = function (fieldType) {
           switch (fieldType) {
             case 'source':
               return '<i class="fa fa-file-text-o "></i>';
@@ -44,12 +44,12 @@ define(function (require) {
           'field.rowCount'
         ], function () {
 
-          var type = $scope.field ? $scope.field.type : $scope.fieldType;
-          var name = $scope.field ? $scope.field.name : $scope.fieldName;
-          var results = $scope.field ? !$scope.field.rowCount && !$scope.field.scripted : false;
-          var scripted = $scope.field ? $scope.field.scripted : false;
+          let type = $scope.field ? $scope.field.type : $scope.fieldType;
+          let name = $scope.field ? $scope.field.name : $scope.fieldName;
+          let results = $scope.field ? !$scope.field.rowCount && !$scope.field.scripted : false;
+          let scripted = $scope.field ? $scope.field.scripted : false;
 
-          var displayName = $filter('shortDots')(name);
+          let displayName = $filter('shortDots')(name);
 
           $el
             .text(displayName)
diff --git a/src/ui/public/directives/file_upload.js b/src/ui/public/directives/file_upload.js
index c9cb4a9f669bc..0bb64bc000bd9 100644
--- a/src/ui/public/directives/file_upload.js
+++ b/src/ui/public/directives/file_upload.js
@@ -1,25 +1,25 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var $ = require('jquery');
+  let module = require('ui/modules').get('kibana');
+  let $ = require('jquery');
 
   module.directive('fileUpload', function ($parse) {
     return {
       restrict: 'A',
       link: function ($scope, $elem, attrs) {
-        var onUpload = $parse(attrs.fileUpload);
+        let onUpload = $parse(attrs.fileUpload);
 
-        var $fileInput = $('<input type="file" style="opacity: 0" id="testfile" />');
+        let $fileInput = $('<input type="file" style="opacity: 0" id="testfile" />');
         $elem.after($fileInput);
 
         $fileInput.on('change', function (e) {
-          var reader = new FileReader();
+          let reader = new FileReader();
           reader.onload = function (e) {
             $scope.$apply(function () {
               onUpload($scope, {fileContents: e.target.result});
             });
           };
 
-          var target = e.srcElement || e.target;
+          let target = e.srcElement || e.target;
           if (target && target.files && target.files.length) reader.readAsText(target.files[0]);
         });
 
diff --git a/src/ui/public/directives/inequality.js b/src/ui/public/directives/inequality.js
index 68e83ed378d05..71d3b1b0df6f6 100644
--- a/src/ui/public/directives/inequality.js
+++ b/src/ui/public/directives/inequality.js
@@ -5,8 +5,8 @@ define(function (require) {
       return {
         require: 'ngModel',
         link: function ($scope, $el, $attr, ngModel) {
-          var getBound = function () { return $parse($attr[id])(); };
-          var defaultVal = {
+          let getBound = function () { return $parse($attr[id])(); };
+          let defaultVal = {
             'greaterThan': -Infinity,
             'lessThan': Infinity
           }[id];
@@ -19,8 +19,8 @@ define(function (require) {
           });
 
           function validate(val) {
-            var bound = !isNaN(getBound()) ? +getBound() : defaultVal;
-            var valid = !isNaN(bound) && !isNaN(val) && compare(val, bound);
+            let bound = !isNaN(getBound()) ? +getBound() : defaultVal;
+            let valid = !isNaN(bound) && !isNaN(val) && compare(val, bound);
             ngModel.$setValidity(id, valid);
             return val;
           }
diff --git a/src/ui/public/directives/infinite_scroll.js b/src/ui/public/directives/infinite_scroll.js
index 2acfe3768116e..52b1479634f74 100644
--- a/src/ui/public/directives/infinite_scroll.js
+++ b/src/ui/public/directives/infinite_scroll.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var $ = require('jquery');
+  let module = require('ui/modules').get('kibana');
+  let $ = require('jquery');
 
   module.directive('kbnInfiniteScroll', function () {
     return {
@@ -9,20 +9,20 @@ define(function (require) {
         more: '='
       },
       link: function ($scope, $element, attrs) {
-        var $window = $(window);
+        let $window = $(window);
         let checkTimer;
 
         function onScroll() {
           if (!$scope.more) return;
 
-          var winHeight = $window.height();
-          var winBottom = winHeight + $window.scrollTop();
-          var elTop = $element.offset().top;
-          var remaining = elTop - winBottom;
+          let winHeight = $window.height();
+          let winBottom = winHeight + $window.scrollTop();
+          let elTop = $element.offset().top;
+          let remaining = elTop - winBottom;
 
           if (remaining <= winHeight * 0.50) {
             $scope[$scope.$$phase ? '$eval' : '$apply'](function () {
-              var more = $scope.more();
+              let more = $scope.more();
             });
           }
         }
diff --git a/src/ui/public/directives/info.js b/src/ui/public/directives/info.js
index a9a69f8a1482d..7e47e63155024 100644
--- a/src/ui/public/directives/info.js
+++ b/src/ui/public/directives/info.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var html = require('ui/partials/info.html');
+  let html = require('ui/partials/info.html');
 
   require('ui/modules')
     .get('kibana')
diff --git a/src/ui/public/directives/input_datetime.js b/src/ui/public/directives/input_datetime.js
index c37aa31318cf9..77cb5669778e9 100644
--- a/src/ui/public/directives/input_datetime.js
+++ b/src/ui/public/directives/input_datetime.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var $ = require('jquery');
-  var _ = require('lodash');
-  var moment = require('moment');
+  let module = require('ui/modules').get('kibana');
+  let $ = require('jquery');
+  let _ = require('lodash');
+  let moment = require('moment');
 
   module.directive('inputDatetime', function () {
     return {
@@ -10,18 +10,18 @@ define(function (require) {
       require: 'ngModel',
       link: function ($scope, $elem, attrs, ngModel) {
 
-        var format = 'YYYY-MM-DD HH:mm:ss.SSS';
+        let format = 'YYYY-MM-DD HH:mm:ss.SSS';
 
         $elem.after('<div class="input-datetime-format">' + format + '</div>');
 
         // What should I make with the input from the user?
-        var fromUser = function (text) {
-          var parsed = moment(text, format);
+        let fromUser = function (text) {
+          let parsed = moment(text, format);
           return parsed.isValid() ? parsed : undefined;
         };
 
         // How should I present the data back to the user in the input field?
-        var toUser = function (datetime) {
+        let toUser = function (datetime) {
           return moment(datetime).format(format);
         };
 
diff --git a/src/ui/public/directives/input_focus.js b/src/ui/public/directives/input_focus.js
index 99cf9dd5d0854..0202e38cf144a 100644
--- a/src/ui/public/directives/input_focus.js
+++ b/src/ui/public/directives/input_focus.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
+  let module = require('ui/modules').get('kibana');
 
   module.directive('inputFocus', function ($timeout) {
     return {
diff --git a/src/ui/public/directives/input_whole_number.js b/src/ui/public/directives/input_whole_number.js
index 1b77b66772ab7..a7307cd1374a0 100644
--- a/src/ui/public/directives/input_whole_number.js
+++ b/src/ui/public/directives/input_whole_number.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
+  let module = require('ui/modules').get('kibana');
 
   module.directive('inputWholeNumber', function () {
     return {
diff --git a/src/ui/public/directives/json_input.js b/src/ui/public/directives/json_input.js
index a8351ed1c7fa4..48cedb5e5dece 100644
--- a/src/ui/public/directives/json_input.js
+++ b/src/ui/public/directives/json_input.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var angular = require('angular');
+  let _ = require('lodash');
+  let angular = require('angular');
 
   require('ui/modules')
   .get('kibana')
@@ -15,7 +15,7 @@ define(function (require) {
         function fromJSON(value) {
           try {
             value = JSON.parse(value);
-            var validity = !scope.$eval(attrs.requireKeys) ? true : _.keys(value).length > 0;
+            let validity = !scope.$eval(attrs.requireKeys) ? true : _.keys(value).length > 0;
             ngModelCntrl.$setValidity('json', validity);
           } catch (e) {
             ngModelCntrl.$setValidity('json', false);
diff --git a/src/ui/public/directives/paginate.js b/src/ui/public/directives/paginate.js
index cac3ee123afc4..8f4110a49b33b 100644
--- a/src/ui/public/directives/paginate.js
+++ b/src/ui/public/directives/paginate.js
@@ -1,7 +1,7 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
-  var PER_PAGE_DEFAULT = 10;
+  let PER_PAGE_DEFAULT = 10;
 
   require('ui/modules').get('kibana')
   .directive('paginate', function ($parse, $compile) {
@@ -21,7 +21,7 @@ define(function (require) {
             $el.prepend($compile('<paginate-controls class="paginate-top">')($scope));
           }
 
-          var paginate = $scope.paginate;
+          let paginate = $scope.paginate;
 
           // add some getters to the controller powered by attributes
           paginate.getList = $parse(attrs.list);
@@ -41,8 +41,8 @@ define(function (require) {
       },
       controllerAs: 'paginate',
       controller: function ($scope) {
-        var self = this;
-        var ALL = 0;
+        let self = this;
+        let ALL = 0;
 
         self.sizeOptions = [
           { title: '10', value: 10 },
@@ -61,8 +61,8 @@ define(function (require) {
             self.perPageProp,
             self.otherWidthGetter
           ], function (vals, oldVals) {
-            var intChanges = vals[0] !== oldVals[0];
-            var extChanges = vals[1] !== oldVals[1];
+            let intChanges = vals[0] !== oldVals[0];
+            let extChanges = vals[1] !== oldVals[1];
 
             if (intChanges) {
               if (!setPerPage(self.perPage)) {
@@ -101,14 +101,14 @@ define(function (require) {
           $scope.pages = [];
           if (!$scope.list) return;
 
-          var perPage = _.parseInt(self.perPage);
-          var count = perPage ? Math.ceil($scope.list.length / perPage) : 1;
+          let perPage = _.parseInt(self.perPage);
+          let count = perPage ? Math.ceil($scope.list.length / perPage) : 1;
 
           _.times(count, function (i) {
             let page;
 
             if (perPage) {
-              var start = perPage * i;
+              let start = perPage * i;
               page = $scope.list.slice(start, start + perPage);
             } else {
               page = $scope.list.slice(0);
@@ -143,9 +143,9 @@ define(function (require) {
 
           // setup the list of the other pages to link to
           $scope.otherPages = [];
-          var width = +self.otherWidthGetter($scope) || 5;
-          var left = page.i - Math.round((width - 1) / 2);
-          var right = left + width - 1;
+          let width = +self.otherWidthGetter($scope) || 5;
+          let left = page.i - Math.round((width - 1) / 2);
+          let right = left + width - 1;
 
           // shift neg count from left to right
           if (left < 0) {
@@ -154,14 +154,14 @@ define(function (require) {
           }
 
           // shift extra right nums to left
-          var lastI = page.count - 1;
+          let lastI = page.count - 1;
           if (right > lastI) {
             right = lastI;
             left = right - width + 1;
           }
 
-          for (var i = left; i <= right; i++) {
-            var other = $scope.pages[i];
+          for (let i = left; i <= right; i++) {
+            let other = $scope.pages[i];
 
             if (!other) continue;
 
@@ -172,7 +172,7 @@ define(function (require) {
         };
 
         function setPerPage(val) {
-          var $ppParent = $scope;
+          let $ppParent = $scope;
 
           while ($ppParent && !_.has($ppParent, self.perPageProp)) {
             $ppParent = $ppParent.$parent;
diff --git a/src/ui/public/directives/pretty_duration.js b/src/ui/public/directives/pretty_duration.js
index dab9106b325a2..0706c47bf39f1 100644
--- a/src/ui/public/directives/pretty_duration.js
+++ b/src/ui/public/directives/pretty_duration.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var _ = require('lodash');
-  var dateMath = require('ui/utils/dateMath');
-  var moment = require('moment');
+  let module = require('ui/modules').get('kibana');
+  let _ = require('lodash');
+  let dateMath = require('ui/utils/dateMath');
+  let moment = require('moment');
 
   require('ui/timepicker/quick_ranges');
   require('ui/timepicker/time_units');
@@ -15,9 +15,9 @@ define(function (require) {
         to: '='
       },
       link: function ($scope, $elem) {
-        var dateFormat = config.get('dateFormat');
+        let dateFormat = config.get('dateFormat');
 
-        var lookupByRange = {};
+        let lookupByRange = {};
         _.each(quickRanges, function (frame) {
           lookupByRange[frame.from + ' to ' + frame.to] = frame;
         });
@@ -26,13 +26,13 @@ define(function (require) {
           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 ' + $scope.to.toString()];
+            let tryLookup = lookupByRange[$scope.from.toString() + ' to ' + $scope.to.toString()];
             if (tryLookup) {
               $elem.text(tryLookup.display);
             } else {
-              var fromParts = $scope.from.toString().split('-');
+              let fromParts = $scope.from.toString().split('-');
               if ($scope.to.toString() === 'now' && fromParts[0] === 'now' && fromParts[1]) {
-                var rounded = fromParts[1].split('/');
+                let rounded = fromParts[1].split('/');
                 text = 'Last ' + rounded[0];
                 if (rounded[1]) {
                   text = text + ' rounded to the ' + timeUnits[rounded[1]];
@@ -49,7 +49,7 @@ define(function (require) {
         };
 
         function cantLookup() {
-          var display = {};
+          let display = {};
           _.each(['from', 'to'], function (time) {
             if (moment.isMoment($scope[time])) {
               display[time] = $scope[time].format(dateFormat);
@@ -57,7 +57,7 @@ define(function (require) {
               if ($scope[time] === 'now') {
                 display[time] = 'now';
               } else {
-                var tryParse = dateMath.parse($scope[time], time === 'to' ? true : false);
+                let tryParse = dateMath.parse($scope[time], time === 'to' ? true : false);
                 display[time] = moment.isMoment(tryParse) ? '~ ' + tryParse.fromNow() : $scope[time];
               }
             }
diff --git a/src/ui/public/directives/rows.js b/src/ui/public/directives/rows.js
index dc29d33389083..55479a376648b 100644
--- a/src/ui/public/directives/rows.js
+++ b/src/ui/public/directives/rows.js
@@ -1,25 +1,25 @@
 define(function (require) {
-  var $ = require('jquery');
-  var _ = require('lodash');
-  var module = require('ui/modules').get('kibana');
-  var AggConfigResult = require('ui/Vis/AggConfigResult');
+  let $ = require('jquery');
+  let _ = require('lodash');
+  let module = require('ui/modules').get('kibana');
+  let AggConfigResult = require('ui/Vis/AggConfigResult');
 
   module.directive('kbnRows', function ($compile, $rootScope, getAppState, Private) {
-    var filterBarClickHandler = Private(require('ui/filter_bar/filter_bar_click_handler'));
+    let filterBarClickHandler = Private(require('ui/filter_bar/filter_bar_click_handler'));
     return {
       restrict: 'A',
       link: function ($scope, $el, attr) {
         function addCell($tr, contents) {
-          var $cell = $(document.createElement('td'));
+          let $cell = $(document.createElement('td'));
 
           // TODO: It would be better to actually check the type of the field, but we don't have
           // access to it here. This may become a problem with the switch to BigNumber
           if (_.isNumeric(contents)) $cell.addClass('numeric-value');
 
-          var createAggConfigResultCell = function (aggConfigResult) {
-            var $cell = $(document.createElement('td'));
-            var $state = getAppState();
-            var clickHandler = filterBarClickHandler($state);
+          let createAggConfigResultCell = function (aggConfigResult) {
+            let $cell = $(document.createElement('td'));
+            let $state = getAppState();
+            let clickHandler = filterBarClickHandler($state);
             $cell.scope = $scope.$new();
             $cell.addClass('cell-hover');
             $cell.attr('ng-click', 'clickHandler($event)');
@@ -70,19 +70,19 @@ define(function (require) {
           attr.kbnRows,
           attr.kbnRowsMin
         ], function (vals) {
-          var rows = vals[0];
-          var min = vals[1];
+          let rows = vals[0];
+          let min = vals[1];
 
           $el.empty();
 
           if (!_.isArray(rows)) rows = [];
-          var width = rows.reduce(maxRowSize, 0);
+          let width = rows.reduce(maxRowSize, 0);
 
           if (isFinite(min) && rows.length < min) {
             // clone the rows so that we can add elements to it without upsetting the original
             rows = _.clone(rows);
             // crate the empty row which will be pushed into the row list over and over
-            var emptyRow = new Array(width);
+            let emptyRow = new Array(width);
             // fill the empty row with values
             _.times(width, function (i) { emptyRow[i] = ''; });
             // push as many empty rows into the row array as needed
@@ -90,7 +90,7 @@ define(function (require) {
           }
 
           rows.forEach(function (row) {
-            var $tr = $(document.createElement('tr')).appendTo($el);
+            let $tr = $(document.createElement('tr')).appendTo($el);
             row.forEach(function (cell) {
               addCell($tr, cell);
             });
diff --git a/src/ui/public/directives/saved_object_finder.js b/src/ui/public/directives/saved_object_finder.js
index 0cd80f51150a6..3b2ae43a2aebd 100644
--- a/src/ui/public/directives/saved_object_finder.js
+++ b/src/ui/public/directives/saved_object_finder.js
@@ -1,12 +1,12 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var _ = require('lodash');
-  var rison = require('ui/utils/rison');
-  var keymap = require('ui/utils/key_map');
+  let module = require('ui/modules').get('kibana');
+  let _ = require('lodash');
+  let rison = require('ui/utils/rison');
+  let keymap = require('ui/utils/key_map');
 
   module.directive('savedObjectFinder', function ($location, $injector, kbnUrl, Private, config) {
 
-    var services = Private(require('ui/saved_objects/saved_object_registry')).byLoaderPropertiesName;
+    let services = Private(require('ui/saved_objects/saved_object_registry')).byLoaderPropertiesName;
 
     return {
       restrict: 'E',
@@ -21,19 +21,19 @@ define(function (require) {
       template: require('ui/partials/saved_object_finder.html'),
       controllerAs: 'finder',
       controller: function ($scope, $element, $timeout) {
-        var self = this;
+        let self = this;
 
         // The number of items to show in the list
         $scope.perPage = config.get('savedObjects:perPage');
 
         // the text input element
-        var $input = $element.find('input[ng-model=filter]');
+        let $input = $element.find('input[ng-model=filter]');
 
         // the list that will hold the suggestions
-        var $list = $element.find('ul');
+        let $list = $element.find('ul');
 
         // the current filter string, used to check that returned results are still useful
-        var currentFilter = $scope.filter;
+        let currentFilter = $scope.filter;
 
         // the most recently entered search/filter
         let prevSearch;
@@ -76,7 +76,7 @@ define(function (require) {
             $scope.userOnChoose(hit, $event);
           }
 
-          var url = self.makeUrl(hit);
+          let url = self.makeUrl(hit);
           if (!url || url === '#' || url.charAt(0) !== '#') return;
 
           $event.preventDefault();
@@ -114,7 +114,7 @@ define(function (require) {
             case 'enter':
               if (self.hitCount !== 1) return;
 
-              var hit = self.hits[0];
+              let hit = self.hits[0];
               if (!hit) return;
 
               self.onChoose(hit, $event);
@@ -187,8 +187,8 @@ define(function (require) {
             case 'enter':
               if (!self.selector.enabled) break;
 
-              var hitIndex = ((page.number - 1) * paginate.perPage) + self.selector.index;
-              var hit = self.hits[hitIndex];
+              let hitIndex = ((page.number - 1) * paginate.perPage) + self.selector.index;
+              let hit = self.hits[hitIndex];
               if (!hit) break;
 
               self.onChoose(hit, $event);
@@ -230,7 +230,7 @@ define(function (require) {
           // but ensure that we don't search for the same
           // thing twice. This is called from multiple places
           // and needs to be smart about when it actually searches
-          var filter = currentFilter;
+          let filter = currentFilter;
           if (prevSearch === filter) return;
 
           prevSearch = filter;
@@ -246,7 +246,7 @@ define(function (require) {
         }
 
         function scrollIntoView($element, snapTop) {
-          var el = $element[0];
+          let el = $element[0];
 
           if (!el) return;
 
diff --git a/src/ui/public/directives/spinner.js b/src/ui/public/directives/spinner.js
index 504cd89de8b4a..f96fb9a8935cb 100644
--- a/src/ui/public/directives/spinner.js
+++ b/src/ui/public/directives/spinner.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var html = '<div class="bounce1"></div> <div class="bounce2"></div> <div class="bounce3"></div>';
-  var module = require('ui/modules').get('kibana');
+  let html = '<div class="bounce1"></div> <div class="bounce2"></div> <div class="bounce3"></div>';
+  let module = require('ui/modules').get('kibana');
 
   module.directive('spinner', function () {
     return {
diff --git a/src/ui/public/directives/truncated.js b/src/ui/public/directives/truncated.js
index 7ae46defff414..ef6882b77585d 100644
--- a/src/ui/public/directives/truncated.js
+++ b/src/ui/public/directives/truncated.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var module = require('ui/modules').get('kibana');
-  var $ = require('jquery');
+  let module = require('ui/modules').get('kibana');
+  let $ = require('jquery');
 
   module.directive('kbnTruncated', function ($compile) {
     return {
@@ -10,14 +10,14 @@ define(function (require) {
         length: '@'
       },
       template: function ($element, attrs) {
-        var template = '<span>{{text}}</span>';
+        let template = '<span>{{text}}</span>';
         template += '<span ng-if="orig.length > length"> <a ng-click="toggle()">{{action}}</a></span>';
         return template;
       },
       link: function ($scope, $element, attrs) {
 
-        var fullText = $scope.orig;
-        var truncated = fullText.substring(0, $scope.length);
+        let fullText = $scope.orig;
+        let truncated = fullText.substring(0, $scope.length);
 
         if (fullText === truncated) {
           $scope.text = fullText;
diff --git a/src/ui/public/directives/validate_cidr_mask.js b/src/ui/public/directives/validate_cidr_mask.js
index 64295872a6377..c8d4e2b6838ea 100644
--- a/src/ui/public/directives/validate_cidr_mask.js
+++ b/src/ui/public/directives/validate_cidr_mask.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var CidrMask = require('ui/utils/CidrMask');
+  let _ = require('lodash');
+  let CidrMask = require('ui/utils/CidrMask');
 
   require('ui/modules').get('kibana').directive('validateCidrMask', function () {
     return {
diff --git a/src/ui/public/directives/validate_date_math.js b/src/ui/public/directives/validate_date_math.js
index 9ab572b59d60b..89e9c920d0786 100644
--- a/src/ui/public/directives/validate_date_math.js
+++ b/src/ui/public/directives/validate_date_math.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var dateMath = require('ui/utils/dateMath');
+  let _ = require('lodash');
+  let dateMath = require('ui/utils/dateMath');
 
   require('ui/modules').get('kibana').directive('validateDateMath', function () {
     return {
@@ -19,7 +19,7 @@ define(function (require) {
             return null;
           }
 
-          var moment = dateMath.parse(input);
+          let moment = dateMath.parse(input);
           ngModel.$setValidity('validDateMath', moment != null && moment.isValid());
           return input;
         }
diff --git a/src/ui/public/directives/validate_index_name.js b/src/ui/public/directives/validate_index_name.js
index 6f5248a7c4c68..84149f50b5024 100644
--- a/src/ui/public/directives/validate_index_name.js
+++ b/src/ui/public/directives/validate_index_name.js
@@ -1,6 +1,6 @@
 // See https://github.com/elastic/elasticsearch/issues/6736
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   require('ui/modules')
     .get('kibana')
@@ -12,11 +12,11 @@ define(function (require) {
           'ngModel': '='
         },
         link: function ($scope, elem, attr, ngModel) {
-          var illegalCharacters = ['\\', '/', '?', '"', '<', '>', '|', ' ', ','];
-          var isValid = function (input) {
+          let illegalCharacters = ['\\', '/', '?', '"', '<', '>', '|', ' ', ','];
+          let isValid = function (input) {
             if (input == null || input === '' || input === '.' || input === '..') return false;
 
-            var match = _.find(illegalCharacters, function (character) {
+            let match = _.find(illegalCharacters, function (character) {
               return input.indexOf(character) >= 0;
             });
             return !match;
@@ -24,7 +24,7 @@ define(function (require) {
 
           // From User
           ngModel.$parsers.unshift(function (value) {
-            var valid = isValid(value);
+            let valid = isValid(value);
             ngModel.$setValidity('indexNameInput', valid);
             return valid ? value : undefined;
           });
diff --git a/src/ui/public/directives/validate_ip.js b/src/ui/public/directives/validate_ip.js
index 6306adaa54ae7..1049603f74c74 100644
--- a/src/ui/public/directives/validate_ip.js
+++ b/src/ui/public/directives/validate_ip.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var Ipv4Address = require('ui/utils/Ipv4Address');
+  let _ = require('lodash');
+  let Ipv4Address = require('ui/utils/Ipv4Address');
 
   require('ui/modules')
     .get('kibana')
diff --git a/src/ui/public/directives/validate_json.js b/src/ui/public/directives/validate_json.js
index 7c429745e4500..c542eb95c3944 100644
--- a/src/ui/public/directives/validate_json.js
+++ b/src/ui/public/directives/validate_json.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var _ = require('lodash');
-  var $ = require('jquery');
+  let _ = require('lodash');
+  let $ = require('jquery');
 
-  var module = require('ui/modules').get('kibana');
+  let module = require('ui/modules').get('kibana');
 
   module.directive('validateJson', function ($compile) {
     return {
diff --git a/src/ui/public/doc_table/components/table_header.js b/src/ui/public/doc_table/components/table_header.js
index 9f6de699c32c5..f1f131b7923a0 100644
--- a/src/ui/public/doc_table/components/table_header.js
+++ b/src/ui/public/doc_table/components/table_header.js
@@ -1,11 +1,11 @@
 define(function (require) {
-  var _ = require('lodash');
-  var module = require('ui/modules').get('app/discover');
+  let _ = require('lodash');
+  let module = require('ui/modules').get('app/discover');
 
   require('ui/filters/short_dots');
 
   module.directive('kbnTableHeader', function (shortDotsFilter) {
-    var headerHtml = require('ui/doc_table/components/table_header.html');
+    let headerHtml = require('ui/doc_table/components/table_header.html');
     return {
       restrict: 'A',
       scope: {
@@ -16,9 +16,9 @@ define(function (require) {
       template: headerHtml,
       controller: function ($scope) {
 
-        var sortableField = function (field) {
+        let sortableField = function (field) {
           if (!$scope.indexPattern) return;
-          var sortable = _.get($scope.indexPattern.fields.byName[field], 'sortable');
+          let sortable = _.get($scope.indexPattern.fields.byName[field], 'sortable');
           return sortable;
         };
 
@@ -34,22 +34,22 @@ define(function (require) {
         $scope.headerClass = function (column) {
           if (!sortableField(column)) return;
 
-          var sorting = $scope.sorting;
-          var defaultClass = ['fa', 'fa-sort-up', 'table-header-sortchange'];
+          let sorting = $scope.sorting;
+          let defaultClass = ['fa', 'fa-sort-up', 'table-header-sortchange'];
 
           if (!sorting || column !== sorting[0]) return defaultClass;
           return ['fa', sorting[1] === 'asc' ? 'fa-sort-up' : 'fa-sort-down'];
         };
 
         $scope.moveLeft = function (column) {
-          var index = _.indexOf($scope.columns, column);
+          let index = _.indexOf($scope.columns, column);
           if (index === 0) return;
 
           _.move($scope.columns, index, --index);
         };
 
         $scope.moveRight = function (column) {
-          var index = _.indexOf($scope.columns, column);
+          let index = _.indexOf($scope.columns, column);
           if (index === $scope.columns.length - 1) return;
 
           _.move($scope.columns, index, ++index);
@@ -62,9 +62,9 @@ define(function (require) {
         $scope.sort = function (column) {
           if (!column || !sortableField(column)) return;
 
-          var sorting = $scope.sorting = $scope.sorting || [];
+          let sorting = $scope.sorting = $scope.sorting || [];
 
-          var direction = sorting[1] || 'asc';
+          let direction = sorting[1] || 'asc';
           if (sorting[0] !== column) {
             direction = 'asc';
           } else {
diff --git a/src/ui/public/doc_table/components/table_row.js b/src/ui/public/doc_table/components/table_row.js
index f81fb902bcc5d..4b50b42705550 100644
--- a/src/ui/public/doc_table/components/table_row.js
+++ b/src/ui/public/doc_table/components/table_row.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var _ = require('lodash');
-  var $ = require('jquery');
-  var addWordBreaks = require('ui/utils/add_word_breaks');
-  var module = require('ui/modules').get('app/discover');
+  let _ = require('lodash');
+  let $ = require('jquery');
+  let addWordBreaks = require('ui/utils/add_word_breaks');
+  let module = require('ui/modules').get('app/discover');
 
   require('ui/highlight');
   require('ui/highlight/highlight_tags');
@@ -12,7 +12,7 @@ define(function (require) {
 
 
   // guesstimate at the minimum number of chars wide cells in the table should be
-  var MIN_LINE_LENGTH = 20;
+  let MIN_LINE_LENGTH = 20;
 
   /**
    * kbnTableRow directive
@@ -23,11 +23,11 @@ define(function (require) {
    * ```
    */
   module.directive('kbnTableRow', function ($compile) {
-    var noWhiteSpace = require('ui/utils/no_white_space');
-    var openRowHtml = require('ui/doc_table/components/table_row/open.html');
-    var detailsHtml = require('ui/doc_table/components/table_row/details.html');
-    var cellTemplate = _.template(noWhiteSpace(require('ui/doc_table/components/table_row/cell.html')));
-    var truncateByHeightTemplate = _.template(noWhiteSpace(require('ui/partials/truncate_by_height.html')));
+    let noWhiteSpace = require('ui/utils/no_white_space');
+    let openRowHtml = require('ui/doc_table/components/table_row/open.html');
+    let detailsHtml = require('ui/doc_table/components/table_row/details.html');
+    let cellTemplate = _.template(noWhiteSpace(require('ui/doc_table/components/table_row/cell.html')));
+    let truncateByHeightTemplate = _.template(noWhiteSpace(require('ui/partials/truncate_by_height.html')));
 
     return {
       restrict: 'A',
@@ -41,7 +41,7 @@ define(function (require) {
         $el.after('<tr>');
         $el.empty();
 
-        var init = function () {
+        let init = function () {
           createSummaryRow($scope.row, $scope.row._id);
         };
 
@@ -53,7 +53,7 @@ define(function (require) {
 
         // toggle display of the rows details, a full list of the fields from each row
         $scope.toggleRow = function () {
-          var $detailsTr = $el.next();
+          let $detailsTr = $el.next();
 
           $scope.open = !$scope.open;
 
@@ -90,10 +90,10 @@ define(function (require) {
 
         // create a tr element that lists the value for each *column*
         function createSummaryRow(row) {
-          var indexPattern = $scope.indexPattern;
+          let indexPattern = $scope.indexPattern;
 
           // We just create a string here because its faster.
-          var newHtmls = [
+          let newHtmls = [
             openRowHtml
           ];
 
@@ -112,18 +112,18 @@ define(function (require) {
             }));
           });
 
-          var $cells = $el.children();
+          let $cells = $el.children();
           newHtmls.forEach(function (html, i) {
-            var $cell = $cells.eq(i);
+            let $cell = $cells.eq(i);
             if ($cell.data('discover:html') === html) return;
 
-            var reuse = _.find($cells.slice(i + 1), function (cell) {
+            let reuse = _.find($cells.slice(i + 1), function (cell) {
               return $.data(cell, 'discover:html') === html;
             });
 
-            var $target = reuse ? $(reuse).detach() : $(html);
+            let $target = reuse ? $(reuse).detach() : $(html);
             $target.data('discover:html', html);
-            var $before = $cells.eq(i - 1);
+            let $before = $cells.eq(i - 1);
             if ($before.size()) {
               $before.after($target);
             } else {
@@ -151,8 +151,8 @@ define(function (require) {
          * Fill an element with the value of a field
          */
         function _displayField(row, fieldName, breakWords) {
-          var indexPattern = $scope.indexPattern;
-          var text = indexPattern.formatField(row, fieldName);
+          let indexPattern = $scope.indexPattern;
+          let text = indexPattern.formatField(row, fieldName);
 
           if (breakWords) {
             text = addWordBreaks(text, MIN_LINE_LENGTH);
diff --git a/src/ui/public/doc_table/doc_table.js b/src/ui/public/doc_table/doc_table.js
index 4bebced3c9743..cba9b87d09391 100644
--- a/src/ui/public/doc_table/doc_table.js
+++ b/src/ui/public/doc_table/doc_table.js
@@ -1,8 +1,8 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
-  var html = require('ui/doc_table/doc_table.html');
-  var getSort = require('ui/doc_table/lib/get_sort');
+  let html = require('ui/doc_table/doc_table.html');
+  let getSort = require('ui/doc_table/lib/get_sort');
 
   require('ui/doc_table/doc_table.less');
   require('ui/directives/truncated');
@@ -25,15 +25,15 @@ define(function (require) {
         filter: '=?',
       },
       link: function ($scope) {
-        var notify = new Notifier();
+        let notify = new Notifier();
         $scope.limit = 50;
         $scope.persist = {
           sorting: $scope.sorting,
           columns: $scope.columns
         };
 
-        var prereq = (function () {
-          var fns = [];
+        let prereq = (function () {
+          let fns = [];
 
           return function register(fn) {
             fns.push(fn);
@@ -59,7 +59,7 @@ define(function (require) {
         $scope.$watch('columns', function (columns) {
           if (columns.length !== 0) return;
 
-          var $state = getAppState();
+          let $state = getAppState();
           $scope.columns.push('_source');
           if ($state) $state.replace();
         });
diff --git a/src/ui/public/doc_table/lib/get_sort.js b/src/ui/public/doc_table/lib/get_sort.js
index 6fa8870bf79c3..1d8a7fea158a9 100644
--- a/src/ui/public/doc_table/lib/get_sort.js
+++ b/src/ui/public/doc_table/lib/get_sort.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   /**
    * Take a sorting array and make it into an object
@@ -8,7 +8,7 @@ define(function (require) {
    * @returns {object} a sort object suitable for returning to elasticsearch
    */
   function getSort(sort, indexPattern) {
-    var sortObj = {};
+    let sortObj = {};
     let field;
     let direction;
 
diff --git a/src/ui/public/doc_title/doc_title.js b/src/ui/public/doc_title/doc_title.js
index bc7898dc692ea..b5f5e6c8a2c77 100644
--- a/src/ui/public/doc_title/doc_title.js
+++ b/src/ui/public/doc_title/doc_title.js
@@ -1,6 +1,6 @@
 define(function (require) {
-  var _ = require('lodash');
-  var chrome = require('ui/chrome');
+  let _ = require('lodash');
+  let chrome = require('ui/chrome');
 
   require('ui/modules').get('kibana')
   .run(function ($rootScope, docTitle) {
@@ -11,16 +11,16 @@ define(function (require) {
     $rootScope.$watch(_.bindKey(chrome, 'getActiveTabTitle'), docTitle.update);
   })
   .service('docTitle', function ($rootScope) {
-    var baseTitle = document.title;
-    var self = this;
+    let baseTitle = document.title;
+    let self = this;
 
     let lastChange;
 
     function render() {
       lastChange = lastChange || [];
 
-      var parts = [lastChange[0]];
-      var activeTabTitle = chrome.getActiveTabTitle();
+      let parts = [lastChange[0]];
+      let activeTabTitle = chrome.getActiveTabTitle();
 
       if (activeTabTitle) parts.push(activeTabTitle);
 
diff --git a/src/ui/public/doc_viewer/doc_viewer.js b/src/ui/public/doc_viewer/doc_viewer.js
index d1359605c846b..2378127b35bff 100644
--- a/src/ui/public/doc_viewer/doc_viewer.js
+++ b/src/ui/public/doc_viewer/doc_viewer.js
@@ -1,9 +1,9 @@
 define(function (require) {
-  var _ = require('lodash');
-  var angular = require('angular');
+  let _ = require('lodash');
+  let angular = require('angular');
   require('ace');
 
-  var html = require('ui/doc_viewer/doc_viewer.html');
+  let html = require('ui/doc_viewer/doc_viewer.html');
   require('ui/doc_viewer/doc_viewer.less');
 
   require('ui/modules').get('kibana')
@@ -38,7 +38,7 @@ define(function (require) {
           };
 
           $scope.showArrayInObjectsWarning = function (row, field) {
-            var value = $scope.flattened[field];
+            let value = $scope.flattened[field];
             return _.isArray(value) && typeof value[0] === 'object';
           };
         }