diff --git a/src/ui/public/Vis/AggConfig.js b/src/ui/public/Vis/AggConfig.js
index 12d9f05450880..8c8cbf89db224 100644
--- a/src/ui/public/Vis/AggConfig.js
+++ b/src/ui/public/Vis/AggConfig.js
@@ -1,10 +1,10 @@
 define(function (require) {
   return function AggConfigFactory(Private, fieldTypeFilter) {
-    var _ = require('lodash');
-    var fieldFormats = Private(require('ui/registry/field_formats'));
+    let _ = require('lodash');
+    let fieldFormats = Private(require('ui/registry/field_formats'));
 
     function AggConfig(vis, opts) {
-      var self = this;
+      let self = this;
 
       self.id = String(opts.id || AggConfig.nextId(vis.aggs));
       self.vis = vis;
@@ -26,13 +26,13 @@ define(function (require) {
      * @return {array} - the list that was passed in
      */
     AggConfig.ensureIds = function (list) {
-      var have = [];
-      var haveNot = [];
+      let have = [];
+      let haveNot = [];
       list.forEach(function (obj) {
         (obj.id ? have : haveNot).push(obj);
       });
 
-      var nextId = AggConfig.nextId(have);
+      let nextId = AggConfig.nextId(have);
       haveNot.forEach(function (obj) {
         obj.id = String(nextId++);
       });
@@ -97,12 +97,12 @@ define(function (require) {
      * @return {undefined}
      */
     AggConfig.prototype.fillDefaults = function (from) {
-      var self = this;
+      let self = this;
       from = from || self.params || {};
-      var to = self.params = {};
+      let to = self.params = {};
 
       self.getAggParams().forEach(function (aggParam) {
-        var val = from[aggParam.name];
+        let val = from[aggParam.name];
 
         if (val == null) {
           if (aggParam.default == null) return;
@@ -116,11 +116,11 @@ define(function (require) {
         }
 
         if (aggParam.deserialize) {
-          var isTyped = _.isFunction(aggParam.type);
+          let isTyped = _.isFunction(aggParam.type);
 
-          var isType = isTyped && (val instanceof aggParam.type);
-          var isObject = !isTyped && _.isObject(val);
-          var isDeserialized = (isType || isObject);
+          let isType = isTyped && (val instanceof aggParam.type);
+          let isObject = !isTyped && _.isObject(val);
+          let isDeserialized = (isType || isObject);
 
           if (!isDeserialized) {
             val = aggParam.deserialize(val, self);
@@ -140,12 +140,12 @@ define(function (require) {
      * @return {object} the new params object
      */
     AggConfig.prototype.resetParams = function () {
-      var fieldParam = this.type && this.type.params.byName.field;
+      let fieldParam = this.type && this.type.params.byName.field;
       let field;
 
       if (fieldParam) {
-        var prevField = this.params.field;
-        var fieldOpts = fieldTypeFilter(this.vis.indexPattern.fields, fieldParam.filterFieldTypes);
+        let prevField = this.params.field;
+        let fieldOpts = fieldTypeFilter(this.vis.indexPattern.fields, fieldParam.filterFieldTypes);
         field = _.contains(fieldOpts, prevField) ? prevField : null;
       }
 
@@ -161,10 +161,10 @@ define(function (require) {
         throw new TypeError('The "' + this.type.title + '" aggregation does not support filtering.');
       }
 
-      var field = this.field();
-      var label = this.fieldDisplayName();
+      let field = this.field();
+      let label = this.fieldDisplayName();
       if (field && !field.filterable) {
-        var message = 'The "' + label + '" field can not be used for filtering.';
+        let message = 'The "' + label + '" field can not be used for filtering.';
         if (field.scripted) {
           message = 'The "' + label + '" field is scripted and can not be used for filtering.';
         }
@@ -181,7 +181,7 @@ define(function (require) {
      * @return {[type]} [description]
      */
     AggConfig.prototype.requesting = function () {
-      var self = this;
+      let self = this;
       self.type && self.type.params.forEach(function (param) {
         if (param.onRequest) param.onRequest(self);
       });
@@ -198,14 +198,14 @@ define(function (require) {
      */
     AggConfig.prototype.toDsl = function () {
       if (this.type.hasNoDsl) return;
-      var output = this.write();
+      let output = this.write();
 
-      var configDsl = {};
+      let configDsl = {};
       configDsl[this.type.dslName || this.type.name] = output.params;
 
       // if the config requires subAggs, write them to the dsl as well
       if (output.subAggs) {
-        var subDslLvl = configDsl.aggs || (configDsl.aggs = {});
+        let subDslLvl = configDsl.aggs || (configDsl.aggs = {});
         output.subAggs.forEach(function nestAdhocSubAggs(subAggConfig) {
           subDslLvl[subAggConfig.id] = subAggConfig.toDsl();
         });
@@ -215,11 +215,11 @@ define(function (require) {
     };
 
     AggConfig.prototype.toJSON = function () {
-      var self = this;
-      var params = self.params;
+      let self = this;
+      let params = self.params;
 
-      var outParams = _.transform(self.getAggParams(), function (out, aggParam) {
-        var val = params[aggParam.name];
+      let outParams = _.transform(self.getAggParams(), function (out, aggParam) {
+        let val = params[aggParam.name];
 
         // don't serialize undefined/null values
         if (val == null) return;
@@ -264,7 +264,7 @@ define(function (require) {
       }
 
       if (!this.type) return '';
-      var pre = (_.get(this.vis, 'params.mode') === 'percentage') ? 'Percentage of ' : '';
+      let pre = (_.get(this.vis, 'params.mode') === 'percentage') ? 'Percentage of ' : '';
       return pre += this.type.makeLabel(this);
     };
 
@@ -273,31 +273,31 @@ define(function (require) {
     };
 
     AggConfig.prototype.fieldFormatter = function (contentType, defaultFormat) {
-      var format = this.type && this.type.getFormat(this);
+      let format = this.type && this.type.getFormat(this);
       if (format) return format.getConverterFor(contentType);
       return this.fieldOwnFormatter(contentType, defaultFormat);
     };
 
     AggConfig.prototype.fieldOwnFormatter = function (contentType, defaultFormat) {
-      var field = this.field();
-      var format = field && field.format;
+      let field = this.field();
+      let format = field && field.format;
       if (!format) format = defaultFormat;
       if (!format) format = fieldFormats.getDefaultInstance('string');
       return format.getConverterFor(contentType);
     };
 
     AggConfig.prototype.fieldName = function () {
-      var field = this.field();
+      let field = this.field();
       return field ? field.name : '';
     };
 
     AggConfig.prototype.fieldDisplayName = function () {
-      var field = this.field();
+      let field = this.field();
       return field ? (field.displayName || this.fieldName()) : '';
     };
 
     AggConfig.prototype.fieldIsTimeField = function () {
-      var timeFieldName = this.vis.indexPattern.timeFieldName;
+      let timeFieldName = this.vis.indexPattern.timeFieldName;
       return timeFieldName && this.fieldName() === timeFieldName;
     };
 
diff --git a/src/ui/public/Vis/AggConfigResult.js b/src/ui/public/Vis/AggConfigResult.js
index b7dac72820efa..4df97b55477c6 100644
--- a/src/ui/public/Vis/AggConfigResult.js
+++ b/src/ui/public/Vis/AggConfigResult.js
@@ -1,5 +1,5 @@
 define(function () {
-  var i = 0;
+  let i = 0;
 
   function AggConfigResult(aggConfig, parent, value, key) {
     this.key = key;
diff --git a/src/ui/public/Vis/AggConfigs.js b/src/ui/public/Vis/AggConfigs.js
index 910c0d5400793..7a9938f942aee 100644
--- a/src/ui/public/Vis/AggConfigs.js
+++ b/src/ui/public/Vis/AggConfigs.js
@@ -1,14 +1,14 @@
 define(function (require) {
   return function AggConfigsFactory(Private) {
-    var _ = require('lodash');
-    var AggConfig = Private(require('ui/Vis/AggConfig'));
-    var IndexedArray = require('ui/IndexedArray');
+    let _ = require('lodash');
+    let AggConfig = Private(require('ui/Vis/AggConfig'));
+    let IndexedArray = require('ui/IndexedArray');
 
     AggConfig.aggTypes = Private(require('ui/agg_types/index'));
 
     _.class(AggConfigs).inherits(IndexedArray);
     function AggConfigs(vis, configStates) {
-      var self = this;
+      let self = this;
       self.vis = vis;
 
       configStates = AggConfig.ensureIds(configStates || []);
@@ -35,9 +35,9 @@ define(function (require) {
         })
         .each(function (schema) {
           if (!self.bySchemaName[schema.name]) {
-            var defaults = schema.defaults.slice(0, schema.max);
+            let defaults = schema.defaults.slice(0, schema.max);
             _.each(defaults, function (defaultState) {
-              var state = _.defaults({ id: AggConfig.nextId(self) }, defaultState);
+              let state = _.defaults({ id: AggConfig.nextId(self) }, defaultState);
               self.push(new AggConfig(vis, state));
             });
           }
@@ -47,7 +47,7 @@ define(function (require) {
     }
 
     AggConfigs.prototype.toDsl = function () {
-      var dslTopLvl = {};
+      let dslTopLvl = {};
       let dslLvlCursor;
       let nestedMetrics;
 
@@ -75,8 +75,8 @@ define(function (require) {
           // start at the top level
           dslLvlCursor = dslTopLvl;
         } else {
-          var prevConfig = list[i - 1];
-          var prevDsl = dslLvlCursor[prevConfig.id];
+          let prevConfig = list[i - 1];
+          let prevDsl = dslLvlCursor[prevConfig.id];
 
           // advance the cursor and nest under the previous agg, or
           // put it on the same level if the previous agg doesn't accept
@@ -84,7 +84,7 @@ define(function (require) {
           dslLvlCursor = prevDsl.aggs || dslLvlCursor;
         }
 
-        var dsl = dslLvlCursor[config.id] = config.toDsl();
+        let dsl = dslLvlCursor[config.id] = config.toDsl();
         let subAggs;
 
         if (config.schema.group === 'buckets' && i < list.length - 1) {
@@ -121,7 +121,7 @@ define(function (require) {
      */
     AggConfigs.prototype.getResponseAggs = function () {
       return this.getRequestAggs().reduce(function (responseValuesAggs, agg) {
-        var aggs = agg.getResponseAggs();
+        let aggs = agg.getResponseAggs();
         return aggs ? responseValuesAggs.concat(aggs) : responseValuesAggs;
       }, []);
     };
@@ -136,7 +136,7 @@ define(function (require) {
      */
     AggConfigs.prototype.getResponseAggById = function (id) {
       id = String(id);
-      var reqAgg = _.find(this.getRequestAggs(), function (agg) {
+      let reqAgg = _.find(this.getRequestAggs(), function (agg) {
         return id.substr(0, String(agg.id).length) === agg.id;
       });
       if (!reqAgg) return;
diff --git a/src/ui/public/Vis/Renderbot.js b/src/ui/public/Vis/Renderbot.js
index a491065889fb2..34533e3ef29c3 100644
--- a/src/ui/public/Vis/Renderbot.js
+++ b/src/ui/public/Vis/Renderbot.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   return function RenderbotFactory(Private) {
 
diff --git a/src/ui/public/Vis/Schemas.js b/src/ui/public/Vis/Schemas.js
index d3b4159f985ee..2b53115059b4e 100644
--- a/src/ui/public/Vis/Schemas.js
+++ b/src/ui/public/Vis/Schemas.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function VisTypeSchemasFactory(Private) {
-    var _ = require('lodash');
-    var IndexedArray = require('ui/IndexedArray');
-    var AggParams = Private(require('ui/agg_types/AggParams'));
+    let _ = require('lodash');
+    let IndexedArray = require('ui/IndexedArray');
+    let AggParams = Private(require('ui/agg_types/AggParams'));
 
     function Schemas(schemas) {
-      var self = this;
+      let self = this;
 
       _(schemas || [])
       .map(function (schema) {
diff --git a/src/ui/public/Vis/Vis.js b/src/ui/public/Vis/Vis.js
index e0e1d268d4b06..d7c72aaafe3d1 100644
--- a/src/ui/public/Vis/Vis.js
+++ b/src/ui/public/Vis/Vis.js
@@ -1,11 +1,11 @@
 define(function (require) {
   return function VisFactory(Notifier, Private) {
-    var _ = require('lodash');
-    var aggTypes = Private(require('ui/agg_types/index'));
-    var visTypes = Private(require('ui/registry/vis_types'));
-    var AggConfigs = Private(require('ui/Vis/AggConfigs'));
+    let _ = require('lodash');
+    let aggTypes = Private(require('ui/agg_types/index'));
+    let visTypes = Private(require('ui/registry/vis_types'));
+    let AggConfigs = Private(require('ui/Vis/AggConfigs'));
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Vis'
     });
 
@@ -29,10 +29,10 @@ define(function (require) {
         type = visTypes.byName[type || 'histogram'];
       }
 
-      var schemas = type.schemas;
+      let schemas = type.schemas;
 
-      var aggs = _.transform(oldState, function (newConfigs, oldConfigs, oldGroupName) {
-        var schema = schemas.all.byName[oldGroupName];
+      let aggs = _.transform(oldState, function (newConfigs, oldConfigs, oldGroupName) {
+        let schema = schemas.all.byName[oldGroupName];
 
         if (!schema) {
           notify.log('unable to match old schema', oldGroupName, 'to a new schema');
@@ -40,12 +40,12 @@ define(function (require) {
         }
 
         oldConfigs.forEach(function (oldConfig) {
-          var agg = {
+          let agg = {
             schema: schema.name,
             type: oldConfig.agg,
           };
 
-          var aggType = aggTypes.byName[agg.type];
+          let aggType = aggTypes.byName[agg.type];
           if (!aggType) {
             notify.log('unable to find an agg type for old confg', oldConfig);
             return;
@@ -116,7 +116,7 @@ define(function (require) {
     };
 
     Vis.prototype.hasSchemaAgg = function (schemaName, aggTypeName) {
-      var aggs = this.aggs.bySchemaName[schemaName] || [];
+      let aggs = this.aggs.bySchemaName[schemaName] || [];
       return aggs.some(function (agg) {
         if (!agg.type || !agg.type.name) return false;
         return agg.type.name === aggTypeName;
diff --git a/src/ui/public/Vis/VisType.js b/src/ui/public/Vis/VisType.js
index 0c995bd108b14..5ba1214ee6ade 100644
--- a/src/ui/public/Vis/VisType.js
+++ b/src/ui/public/Vis/VisType.js
@@ -1,6 +1,6 @@
 define(function (require) {
   return function VisTypeFactory(Private) {
-    var VisTypeSchemas = Private(require('ui/Vis/Schemas'));
+    let VisTypeSchemas = Private(require('ui/Vis/Schemas'));
 
     function VisType(opts) {
       opts = opts || {};
diff --git a/src/ui/public/url/url.js b/src/ui/public/url/url.js
index bede54413b9f7..bff12c1758f65 100644
--- a/src/ui/public/url/url.js
+++ b/src/ui/public/url/url.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   require('ui/filters/uriescape');
   require('ui/filters/rison');
@@ -8,7 +8,7 @@ define(function (require) {
   .service('kbnUrl', function (Private) { return Private(KbnUrlProvider); });
 
   function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getAppState) {
-    var self = this;
+    let self = this;
 
     /**
      * Navigate to a url
@@ -70,10 +70,10 @@ define(function (require) {
 
       return template.replace(/\{\{([^\}]+)\}\}/g, function (match, expr) {
         // remove filters
-        var key = expr.split('|')[0].trim();
+        let key = expr.split('|')[0].trim();
 
         // verify that the expression can be evaluated
-        var p = $parse(key)(paramObj);
+        let p = $parse(key)(paramObj);
 
         // if evaluation can't be made, throw
         if (_.isUndefined(p)) {
@@ -109,7 +109,7 @@ define(function (require) {
      * @return {string} - the computed url
      */
     self.getRouteUrl = function (obj, route) {
-      var template = obj && obj.routes && obj.routes[route];
+      let template = obj && obj.routes && obj.routes[route];
       if (template) return self.eval(template, obj);
     };
 
@@ -143,7 +143,7 @@ define(function (require) {
     let reloading;
 
     self._changeLocation = function (type, url, paramObj, replace) {
-      var prev = {
+      let prev = {
         path: $location.path(),
         search: $location.search()
       };
@@ -152,13 +152,13 @@ define(function (require) {
       $location[type](url);
       if (replace) $location.replace();
 
-      var next = {
+      let next = {
         path: $location.path(),
         search: $location.search()
       };
 
       if (self._shouldAutoReload(next, prev)) {
-        var appState = getAppState();
+        let appState = getAppState();
         if (appState) appState.destroy();
 
         reloading = $rootScope.$on('$locationChangeSuccess', function () {
@@ -174,13 +174,13 @@ define(function (require) {
     self._shouldAutoReload = function (next, prev) {
       if (reloading) return false;
 
-      var route = $route.current && $route.current.$$route;
+      let route = $route.current && $route.current.$$route;
       if (!route) return false;
 
       if (next.path !== prev.path) return false;
 
-      var reloadOnSearch = route.reloadOnSearch;
-      var searchSame = _.isEqual(next.search, prev.search);
+      let reloadOnSearch = route.reloadOnSearch;
+      let searchSame = _.isEqual(next.search, prev.search);
 
       return (reloadOnSearch && searchSame) || !reloadOnSearch;
     };
diff --git a/src/ui/public/vislib_vis_type/VislibRenderbot.js b/src/ui/public/vislib_vis_type/VislibRenderbot.js
index 18ccadd614515..9133c79aef273 100644
--- a/src/ui/public/vislib_vis_type/VislibRenderbot.js
+++ b/src/ui/public/vislib_vis_type/VislibRenderbot.js
@@ -1,8 +1,8 @@
 module.exports = function VislibRenderbotFactory(Private) {
-  var _ = require('lodash');
-  var vislib = Private(require('ui/vislib'));
-  var Renderbot = Private(require('ui/Vis/Renderbot'));
-  var buildChartData = Private(require('ui/vislib_vis_type/buildChartData'));
+  let _ = require('lodash');
+  let vislib = Private(require('ui/vislib'));
+  let Renderbot = Private(require('ui/Vis/Renderbot'));
+  let buildChartData = Private(require('ui/vislib_vis_type/buildChartData'));
 
   _.class(VislibRenderbot).inherits(Renderbot);
   function VislibRenderbot(vis, $el, uiState) {
@@ -11,7 +11,7 @@ module.exports = function VislibRenderbotFactory(Private) {
   }
 
   VislibRenderbot.prototype._createVis = function () {
-    var self = this;
+    let self = this;
 
     if (self.vislibVis) self.destroy();
 
@@ -26,7 +26,7 @@ module.exports = function VislibRenderbotFactory(Private) {
   };
 
   VislibRenderbot.prototype._getVislibParams = function () {
-    var self = this;
+    let self = this;
 
     return _.assign(
       {},
@@ -47,9 +47,9 @@ module.exports = function VislibRenderbotFactory(Private) {
   };
 
   VislibRenderbot.prototype.destroy = function () {
-    var self = this;
+    let self = this;
 
-    var vislibVis = self.vislibVis;
+    let vislibVis = self.vislibVis;
 
     _.forOwn(self.vis.listeners, function (listener, event) {
       vislibVis.off(event, listener);
@@ -59,10 +59,10 @@ module.exports = function VislibRenderbotFactory(Private) {
   };
 
   VislibRenderbot.prototype.updateParams = function () {
-    var self = this;
+    let self = this;
 
     // get full vislib params object
-    var newParams = self._getVislibParams();
+    let newParams = self._getVislibParams();
 
     // if there's been a change, replace the vis
     if (!_.isEqual(newParams, self.vislibParams)) self._createVis();
diff --git a/src/ui/public/vislib_vis_type/VislibVisType.js b/src/ui/public/vislib_vis_type/VislibVisType.js
index 91890c1591cd5..2957deddbb60d 100644
--- a/src/ui/public/vislib_vis_type/VislibVisType.js
+++ b/src/ui/public/vislib_vis_type/VislibVisType.js
@@ -1,12 +1,12 @@
 define(function (require) {
   return function VislibVisTypeFactory(Private) {
-    var _ = require('lodash');
+    let _ = require('lodash');
 
     require('ui/vislib');
-    var VisTypeSchemas = Private(require('ui/Vis/Schemas'));
-    var VisType = Private(require('ui/Vis/VisType'));
-    var pointSeries = Private(require('ui/agg_response/point_series/point_series'));
-    var VislibRenderbot = Private(require('ui/vislib_vis_type/VislibRenderbot'));
+    let VisTypeSchemas = Private(require('ui/Vis/Schemas'));
+    let VisType = Private(require('ui/Vis/VisType'));
+    let pointSeries = Private(require('ui/agg_response/point_series/point_series'));
+    let VislibRenderbot = Private(require('ui/vislib_vis_type/VislibRenderbot'));
 
     require('plugins/kbn_vislib_vis_types/controls/vislib_basic_options');
     require('plugins/kbn_vislib_vis_types/controls/point_series_options');
diff --git a/src/ui/public/vislib_vis_type/buildChartData.js b/src/ui/public/vislib_vis_type/buildChartData.js
index acc1042ff095e..22373c8632648 100644
--- a/src/ui/public/vislib_vis_type/buildChartData.js
+++ b/src/ui/public/vislib_vis_type/buildChartData.js
@@ -1,22 +1,22 @@
 define(function (require) {
   return function VislibVisBuildChartData(Private) {
-    var aggResponse = Private(require('ui/agg_response/index'));
-    var Table = Private(require('ui/agg_response/tabify/_table'));
+    let aggResponse = Private(require('ui/agg_response/index'));
+    let Table = Private(require('ui/agg_response/tabify/_table'));
 
     return function (esResponse) {
-      var vis = this.vis;
+      let vis = this.vis;
 
       if (vis.isHierarchical()) {
         // the hierarchical converter is very self-contained (woot!)
         return aggResponse.hierarchical(vis, esResponse);
       }
 
-      var tableGroup = aggResponse.tabify(vis, esResponse, {
+      let tableGroup = aggResponse.tabify(vis, esResponse, {
         canSplit: true,
         asAggConfigResults: true
       });
 
-      var converted = convertTableGroup(vis, tableGroup);
+      let converted = convertTableGroup(vis, tableGroup);
       if (!converted) {
         // mimic a row of tables that doesn't have any tables
         // https://github.com/elastic/kibana/blob/7bfb68cd24ed42b1b257682f93c50cd8d73e2520/src/kibana/components/vislib/components/zero_injection/inject_zeros.js#L32
@@ -29,11 +29,11 @@ define(function (require) {
     };
 
     function convertTableGroup(vis, tableGroup) {
-      var tables = tableGroup.tables;
-      var firstChild = tables[0];
+      let tables = tableGroup.tables;
+      let firstChild = tables[0];
       if (firstChild instanceof Table) {
 
-        var chart = convertTable(vis, firstChild);
+        let chart = convertTable(vis, firstChild);
         // if chart is within a split, assign group title to its label
         if (tableGroup.$parent) {
           chart.label = tableGroup.title;
@@ -42,13 +42,13 @@ define(function (require) {
       }
 
       if (!tables.length) return;
-      var out = {};
+      let out = {};
       let outList;
 
       tables.forEach(function (table) {
         if (!outList) {
-          var aggConfig = table.aggConfig;
-          var direction = aggConfig.params.row ? 'rows' : 'columns';
+          let aggConfig = table.aggConfig;
+          let direction = aggConfig.params.row ? 'rows' : 'columns';
           outList = out[direction] = [];
         }
 
diff --git a/src/ui/public/visualize/spy.js b/src/ui/public/visualize/spy.js
index 3abbebfc1bad7..fd4db67aa085e 100644
--- a/src/ui/public/visualize/spy.js
+++ b/src/ui/public/visualize/spy.js
@@ -2,19 +2,19 @@ define(function (require) {
   require('ui/modules')
     .get('app/visualize')
     .directive('visualizeSpy', function (Private, $compile) {
-      var $ = require('jquery');
-      var _ = require('lodash');
+      let $ = require('jquery');
+      let _ = require('lodash');
 
-      var spyModes = Private(require('ui/registry/spy_modes'));
-      var defaultMode = spyModes.inOrder[0].name;
+      let spyModes = Private(require('ui/registry/spy_modes'));
+      let defaultMode = spyModes.inOrder[0].name;
 
       return {
         restrict: 'E',
         template: require('ui/visualize/spy.html'),
         link: function ($scope, $el) {
           let currentSpy;
-          var $container = $el.find('.visualize-spy-container');
-          var fullPageSpy = _.get($scope.spy, 'mode.fill', false);
+          let $container = $el.find('.visualize-spy-container');
+          let fullPageSpy = _.get($scope.spy, 'mode.fill', false);
           $scope.modes = spyModes;
           $scope.spy.params = $scope.spy.params || {};
 
@@ -28,8 +28,8 @@ define(function (require) {
             };
           }
 
-          var renderSpy = function (spyName) {
-            var newMode = $scope.modes.byName[spyName];
+          let renderSpy = function (spyName) {
+            let newMode = $scope.modes.byName[spyName];
 
             // clear the current value
             if (currentSpy) {
@@ -55,7 +55,7 @@ define(function (require) {
           };
 
           $scope.toggleDisplay = function () {
-            var modeName = _.get($scope.spy, 'mode.name');
+            let modeName = _.get($scope.spy, 'mode.name');
             $scope.setSpyMode(modeName ? null : defaultMode);
           };
 
@@ -72,7 +72,7 @@ define(function (require) {
 
           if ($scope.uiState) {
             // sync external uiState changes
-            var syncUIState = () => $scope.spy.mode = $scope.uiState.get('spy.mode');
+            let syncUIState = () => $scope.spy.mode = $scope.uiState.get('spy.mode');
             $scope.uiState.on('change', syncUIState);
             $scope.$on('$destroy', () => $scope.uiState.off('change', syncUIState));
           }
@@ -83,7 +83,7 @@ define(function (require) {
             'spy.mode.fill'
           ], function (newVals, oldVals) {
             // update the ui state, but only if it really changes
-            var changedVals = newVals.filter((val) => !_.isUndefined(val)).length > 0;
+            let changedVals = newVals.filter((val) => !_.isUndefined(val)).length > 0;
             if (changedVals && !_.isEqual(newVals, oldVals)) {
               if ($scope.uiState) $scope.uiState.set('spy.mode', $scope.spy.mode);
             }
diff --git a/src/ui/public/visualize/visualize.js b/src/ui/public/visualize/visualize.js
index 1fd1dd7b527ed..522764dd21ac2 100644
--- a/src/ui/public/visualize/visualize.js
+++ b/src/ui/public/visualize/visualize.js
@@ -7,11 +7,11 @@ define(function (require) {
     require('ui/visualize/visualize.less');
     require('ui/visualize/visualize_legend');
 
-    var $ = require('jquery');
-    var _ = require('lodash');
-    var visTypes = Private(require('ui/registry/vis_types'));
+    let $ = require('jquery');
+    let _ = require('lodash');
+    let visTypes = Private(require('ui/registry/vis_types'));
 
-    var notify = new Notifier({
+    let notify = new Notifier({
       location: 'Visualize'
     });
 
@@ -28,7 +28,7 @@ define(function (require) {
       template: require('ui/visualize/visualize.html'),
       link: function ($scope, $el, attr) {
         let chart; // set in "vis" watcher
-        var minVisChartHeight = 180;
+        let minVisChartHeight = 180;
 
         if (_.isUndefined($scope.showSpyPanel)) {
           $scope.showSpyPanel = true;
@@ -36,19 +36,19 @@ define(function (require) {
 
         function getter(selector) {
           return function () {
-            var $sel = $el.find(selector);
+            let $sel = $el.find(selector);
             if ($sel.size()) return $sel;
           };
         }
 
-        var getVisEl = getter('.visualize-chart');
-        var getVisContainer = getter('.vis-container');
+        let getVisEl = getter('.visualize-chart');
+        let getVisContainer = getter('.vis-container');
 
         // Show no results message when isZeroHits is true and it requires search
         $scope.showNoResultsMessage = function () {
-          var requiresSearch = _.get($scope, 'vis.type.requiresSearch');
-          var isZeroHits = _.get($scope,'esResp.hits.total') === 0;
-          var shouldShowMessage = !_.get($scope, 'vis.params.handleNoResults');
+          let requiresSearch = _.get($scope, 'vis.type.requiresSearch');
+          let isZeroHits = _.get($scope,'esResp.hits.total') === 0;
+          let shouldShowMessage = !_.get($scope, 'vis.params.handleNoResults');
 
           return Boolean(requiresSearch && isZeroHits && shouldShowMessage);
         };
@@ -57,9 +57,9 @@ define(function (require) {
         $scope.spy = {};
         $scope.spy.mode = ($scope.uiState) ? $scope.uiState.get('spy.mode', {}) : {};
 
-        var applyClassNames = function () {
-          var $visEl = getVisContainer();
-          var fullSpy = ($scope.spy.mode && ($scope.spy.mode.fill || $scope.fullScreenSpy));
+        let applyClassNames = function () {
+          let $visEl = getVisContainer();
+          let fullSpy = ($scope.spy.mode && ($scope.spy.mode.fill || $scope.fullScreenSpy));
 
           $visEl.toggleClass('spy-only', Boolean(fullSpy));
 
@@ -72,8 +72,8 @@ define(function (require) {
 
         // we need to wait for some watchers to fire at least once
         // before we are "ready", this manages that
-        var prereq = (function () {
-          var fns = [];
+        let prereq = (function () {
+          let fns = [];
 
           return function register(fn) {
             fns.push(fn);
@@ -91,14 +91,14 @@ define(function (require) {
           };
         }());
 
-        var loadingDelay = config.get('visualization:loadingDelay');
+        let loadingDelay = config.get('visualization:loadingDelay');
         $scope.loadingStyle = {
           '-webkit-transition-delay': loadingDelay,
           'transition-delay': loadingDelay
         };
 
         function shouldHaveFullSpy() {
-          var $visEl = getVisEl();
+          let $visEl = getVisEl();
           if (!$visEl) return;
 
           return ($visEl.height() < minVisChartHeight)
@@ -115,7 +115,7 @@ define(function (require) {
         });
 
         $scope.$watch('vis', prereq(function (vis, oldVis) {
-          var $visEl = getVisEl();
+          let $visEl = getVisEl();
           if (!$visEl) return;
 
           if (!attr.editableVis) {
diff --git a/src/ui/public/visualize/visualize_legend.js b/src/ui/public/visualize/visualize_legend.js
index 6ef1fd30c3168..2e9a8f3a7e068 100644
--- a/src/ui/public/visualize/visualize_legend.js
+++ b/src/ui/public/visualize/visualize_legend.js
@@ -1,23 +1,23 @@
 define(function (require) {
-  var _ = require('lodash');
-  var html = require('ui/visualize/visualize_legend.html');
+  let _ = require('lodash');
+  let html = require('ui/visualize/visualize_legend.html');
 
-  var $ = require('jquery');
-  var d3 = require('d3');
-  var findByParam = require('ui/utils/find_by_param');
+  let $ = require('jquery');
+  let d3 = require('d3');
+  let findByParam = require('ui/utils/find_by_param');
 
   require('ui/modules').get('kibana')
   .directive('visualizeLegend', function (Private, getAppState) {
-    var Data = Private(require('ui/vislib/lib/data'));
-    var colorPalette = Private(require('ui/vislib/components/color/color'));
-    var filterBarClickHandler = Private(require('ui/filter_bar/filter_bar_click_handler'));
+    let Data = Private(require('ui/vislib/lib/data'));
+    let colorPalette = Private(require('ui/vislib/components/color/color'));
+    let filterBarClickHandler = Private(require('ui/filter_bar/filter_bar_click_handler'));
 
     return {
       restrict: 'E',
       template: html,
       link: function ($scope, $elem) {
-        var $state = getAppState();
-        var clickHandler = filterBarClickHandler($state);
+        let $state = getAppState();
+        let clickHandler = filterBarClickHandler($state);
         $scope.open = $scope.uiState.get('vis.legendOpen', true);
 
         $scope.$watch('renderbot.chartData', function (data) {
@@ -27,29 +27,29 @@ define(function (require) {
         });
 
         $scope.highlight = function (event) {
-          var el = event.currentTarget;
-          var handler = $scope.renderbot.vislibVis.handler;
+          let el = event.currentTarget;
+          let handler = $scope.renderbot.vislibVis.handler;
           if (!handler) return;
           handler.highlight.call(el, handler.el);
         };
 
         $scope.unhighlight = function (event) {
-          var el = event.currentTarget;
-          var handler = $scope.renderbot.vislibVis.handler;
+          let el = event.currentTarget;
+          let handler = $scope.renderbot.vislibVis.handler;
           if (!handler) return;
           handler.unHighlight.call(el, handler.el);
         };
 
         $scope.setColor = function (label, color) {
-          var colors = $scope.uiState.get('vis.colors') || {};
+          let colors = $scope.uiState.get('vis.colors') || {};
           colors[label] = color;
           $scope.uiState.set('vis.colors', colors);
           refresh();
         };
 
         $scope.toggleLegend = function () {
-          var bwcAddLegend = $scope.renderbot.vislibVis._attr.addLegend;
-          var bwcLegendStateDefault = bwcAddLegend == null ? true : bwcAddLegend;
+          let bwcAddLegend = $scope.renderbot.vislibVis._attr.addLegend;
+          let bwcLegendStateDefault = bwcAddLegend == null ? true : bwcAddLegend;
           $scope.open = !$scope.uiState.get('vis.legendOpen', bwcLegendStateDefault);
           $scope.uiState.set('vis.legendOpen', $scope.open);
         };
@@ -59,7 +59,7 @@ define(function (require) {
         };
 
         $scope.canFilter = function (legendData) {
-          var filters = clickHandler({point: legendData}, true) || [];
+          let filters = clickHandler({point: legendData}, true) || [];
           return filters.length;
         };
 
@@ -74,7 +74,7 @@ define(function (require) {
         ];
 
         function refresh() {
-          var vislibVis = $scope.renderbot.vislibVis;
+          let vislibVis = $scope.renderbot.vislibVis;
 
           if ($scope.uiState.get('vis.legendOpen') == null && vislibVis._attr.addLegend != null) {
             $scope.open = vislibVis._attr.addLegend;
@@ -87,13 +87,13 @@ define(function (require) {
         // Most of these functions were moved directly from the old Legend class. Not a fan of this.
         function getLabels(data, type) {
           if (!data) return [];
-          var data = data.columns || data.rows || [data];
+          data = data.columns || data.rows || [data];
           if (type === 'pie') return Data.prototype.pieNames(data);
           return getSeriesLabels(data);
         };
 
         function getSeriesLabels(data) {
-          var values = data.map(function (chart) {
+          let values = data.map(function (chart) {
             return chart.series;
           })
           .reduce(function (a, b) {
diff --git a/src/ui/public/watch_multi/watch_multi.js b/src/ui/public/watch_multi/watch_multi.js
index 4bfcadfacf29e..9544597b7223e 100644
--- a/src/ui/public/watch_multi/watch_multi.js
+++ b/src/ui/public/watch_multi/watch_multi.js
@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   require('ui/modules').get('kibana')
   .config(function ($provide) {
@@ -37,15 +37,15 @@ define(function (require) {
         if (!_.isArray(expressions)) throw new TypeError('expected an array of expressions to watch');
         if (!_.isFunction(fn)) throw new TypeError('expected a function that is triggered on each watch');
 
-        var $scope = this;
-        var vals = new Array(expressions.length);
-        var prev = new Array(expressions.length);
-        var fire = false;
-        var init = 0;
-        var neededInits = expressions.length;
+        let $scope = this;
+        let vals = new Array(expressions.length);
+        let prev = new Array(expressions.length);
+        let fire = false;
+        let init = 0;
+        let neededInits = expressions.length;
 
         // first, register all of the multi-watchers
-        var unwatchers = expressions.map(function (expr, i) {
+        let unwatchers = expressions.map(function (expr, i) {
           expr = normalizeExpression($scope, expr);
           if (!expr) return;
 
@@ -62,7 +62,7 @@ define(function (require) {
 
         // then, the watcher that checks to see if any of
         // the other watchers triggered this cycle
-        var flip = false;
+        let flip = false;
         unwatchers.push($scope.$watch(function () {
           if (init < neededInits) return init;
 
@@ -85,7 +85,7 @@ define(function (require) {
 
       function normalizeExpression($scope, expr) {
         if (!expr) return;
-        var norm = {
+        let norm = {
           fn: $scope.$watch,
           deep: false
         };