diff --git a/src/ui/public/url/url.js b/src/ui/public/url/url.js
index a5c7cf0eebf30..cd3ed891e28fb 100644
--- a/src/ui/public/url/url.js
+++ b/src/ui/public/url/url.js
@@ -8,7 +8,7 @@ uiModules.get('kibana/url')
 .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 @@ function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getA
 
     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 @@ function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getA
    * @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 @@ function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getA
   let reloading;
 
   self._changeLocation = function (type, url, paramObj, replace) {
-    var prev = {
+    let prev = {
       path: $location.path(),
       search: $location.search()
     };
@@ -152,13 +152,13 @@ function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getA
     $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('$locationChangeSuccess', function () {
@@ -174,13 +174,13 @@ function KbnUrlProvider($route, $location, $rootScope, globalState, $parse, getA
   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/utils/add_word_breaks.js b/src/ui/public/utils/add_word_breaks.js
index 99c35649eedd2..6f2454e93ebe4 100644
--- a/src/ui/public/utils/add_word_breaks.js
+++ b/src/ui/public/utils/add_word_breaks.js
@@ -1,13 +1,13 @@
 define(function () {
   return function addWordBreaks(text, minLineLength) {
     text = text || '';
-    var lineSize = 0;
-    var newText = '';
-    var inHtmlTag = false;
-    var inHtmlChar = false;
+    let lineSize = 0;
+    let newText = '';
+    let inHtmlTag = false;
+    let inHtmlChar = false;
 
-    for (var i = 0, len = text.length; i < len; i++) {
-      var chr = text.charAt(i);
+    for (let i = 0, len = text.length; i < len; i++) {
+      let chr = text.charAt(i);
       newText += chr;
 
       switch (chr) {
diff --git a/src/ui/public/utils/brush_event.js b/src/ui/public/utils/brush_event.js
index 670e8af5eb9de..9ecdc074d784d 100644
--- a/src/ui/public/utils/brush_event.js
+++ b/src/ui/public/utils/brush_event.js
@@ -1,8 +1,8 @@
 import moment from 'moment';
 export default function brushEventProvider(timefilter) {
   return function (event) {
-    var from = moment(event.range[0]);
-    var to = moment(event.range[1]);
+    let from = moment(event.range[0]);
+    let to = moment(event.range[1]);
 
     if (to - from === 0) return;
 
diff --git a/src/ui/public/utils/cidr_mask.js b/src/ui/public/utils/cidr_mask.js
index 88e3e5f27fc9e..a0ae16709538c 100644
--- a/src/ui/public/utils/cidr_mask.js
+++ b/src/ui/public/utils/cidr_mask.js
@@ -1,12 +1,12 @@
 import Ipv4Address from 'ui/utils/ipv4_address';
-var NUM_BITS = 32;
+let NUM_BITS = 32;
 
 function throwError(mask) {
   throw Error('Invalid CIDR mask: ' + mask);
 }
 
 function CidrMask(mask) {
-  var splits = mask.split('\/');
+  let splits = mask.split('\/');
   if (splits.length !== 2) throwError(mask);
   this.initialAddress = new Ipv4Address(splits[0]);
   this.prefixLength = Number(splits[1]);
@@ -14,9 +14,9 @@ function CidrMask(mask) {
 }
 
 CidrMask.prototype.getRange = function () {
-  var variableBits = NUM_BITS - this.prefixLength;
-  var fromAddress = this.initialAddress.valueOf() >> variableBits << variableBits >>> 0; // >>> 0 coerces to unsigned
-  var numAddresses = Math.pow(2, variableBits);
+  let variableBits = NUM_BITS - this.prefixLength;
+  let fromAddress = this.initialAddress.valueOf() >> variableBits << variableBits >>> 0; // >>> 0 coerces to unsigned
+  let numAddresses = Math.pow(2, variableBits);
   return {
     from: new Ipv4Address(fromAddress).toString(),
     to: new Ipv4Address(fromAddress + numAddresses - 1).toString()
diff --git a/src/ui/public/utils/date_math.js b/src/ui/public/utils/date_math.js
index 0c5ccf6e8c679..cefabf4fcc40a 100644
--- a/src/ui/public/utils/date_math.js
+++ b/src/ui/public/utils/date_math.js
@@ -1,11 +1,11 @@
 import _ from 'lodash';
 import moment from 'moment';
 
-var units = ['y', 'M', 'w', 'd', 'h', 'm', 's', 'ms'];
-var unitsAsc = _.sortBy(units, function (unit) {
+let units = ['y', 'M', 'w', 'd', 'h', 'm', 's', 'ms'];
+let unitsAsc = _.sortBy(units, function (unit) {
   return moment.duration(1, unit).valueOf();
 });
-var unitsDesc = unitsAsc.reverse();
+let unitsDesc = unitsAsc.reverse();
 
 /* This is a simplified version of elasticsearch's date parser */
 function parse(text, roundUp) {
@@ -14,7 +14,7 @@ function parse(text, roundUp) {
   if (_.isDate(text)) return moment(text);
 
   let time;
-  var mathString = '';
+  let mathString = '';
   let index;
   let parseString;
 
@@ -42,12 +42,12 @@ function parse(text, roundUp) {
 }
 
 function parseDateMath(mathString, time, roundUp) {
-  var dateTime = time;
-  var i = 0;
-  var len = mathString.length;
+  let dateTime = time;
+  let i = 0;
+  let len = mathString.length;
 
   while (i < len) {
-    var c = mathString.charAt(i++);
+    let c = mathString.charAt(i++);
     let type;
     let num;
     let unit;
@@ -67,7 +67,7 @@ function parseDateMath(mathString, time, roundUp) {
     } else if (mathString.length === 2) {
       num = mathString.charAt(i);
     } else {
-      var numFrom = i;
+      let numFrom = i;
       while (!isNaN(mathString.charAt(i))) {
         i++;
         if (i > 10) return undefined;
diff --git a/src/ui/public/utils/date_range.js b/src/ui/public/utils/date_range.js
index f65a013f4e1c7..4b4b153fbafbf 100644
--- a/src/ui/public/utils/date_range.js
+++ b/src/ui/public/utils/date_range.js
@@ -11,7 +11,7 @@ export default {
     }
   },
   parse: function (rangeString, format) {
-    var chunks = rangeString.split(' to ');
+    let chunks = rangeString.split(' to ');
     if (chunks.length === 2) return {from: moment(chunks[0], format), to: moment(chunks[1], format)};
 
     chunks = rangeString.split('Before ');
diff --git a/src/ui/public/utils/decode_geo_hash.js b/src/ui/public/utils/decode_geo_hash.js
index 0cd65f7c39751..1a1a375c12379 100644
--- a/src/ui/public/utils/decode_geo_hash.js
+++ b/src/ui/public/utils/decode_geo_hash.js
@@ -16,22 +16,22 @@
  * @return {Object} interval
  */
 function decodeGeoHash(geohash) {
-  var BITS = [16, 8, 4, 2, 1];
-  var BASE32 = '0123456789bcdefghjkmnpqrstuvwxyz';
-  var is_even = 1;
-  var lat = [];
-  var lon = [];
+  let BITS = [16, 8, 4, 2, 1];
+  let BASE32 = '0123456789bcdefghjkmnpqrstuvwxyz';
+  let is_even = 1;
+  let lat = [];
+  let lon = [];
   lat[0] = -90.0;
   lat[1] = 90.0;
   lon[0] = -180.0;
   lon[1] = 180.0;
-  var lat_err = 90.0;
-  var lon_err = 180.0;
-  for (var i = 0; i < geohash.length; i++) {
-    var c = geohash[i];
-    var cd = BASE32.indexOf(c);
-    for (var j = 0; j < 5; j++) {
-      var mask = BITS[j];
+  let lat_err = 90.0;
+  let lon_err = 180.0;
+  for (let i = 0; i < geohash.length; i++) {
+    let c = geohash[i];
+    let cd = BASE32.indexOf(c);
+    for (let j = 0; j < 5; j++) {
+      let mask = BITS[j];
       if (is_even) {
         lon_err /= 2;
         refine_interval(lon, cd, mask);
diff --git a/src/ui/public/utils/diff_object.js b/src/ui/public/utils/diff_object.js
index f1e8dd57ea711..25df114df3729 100644
--- a/src/ui/public/utils/diff_object.js
+++ b/src/ui/public/utils/diff_object.js
@@ -3,14 +3,14 @@ import angular from 'angular';
 
 export default function (target, source) {
 
-  var diff = {};
+  let diff = {};
 
   /**
    * Filter the private vars
    * @param {string} key The keys
    * @returns {boolean}
    */
-  var filterPrivateAndMethods = function (obj) {
+  let filterPrivateAndMethods = function (obj) {
     return function (key) {
       if (_.isFunction(obj[key])) return false;
       if (key.charAt(0) === '$') return false;
@@ -18,8 +18,8 @@ export default function (target, source) {
     };
   };
 
-  var targetKeys = _.keys(target).filter(filterPrivateAndMethods(target));
-  var sourceKeys = _.keys(source).filter(filterPrivateAndMethods(source));
+  let targetKeys = _.keys(target).filter(filterPrivateAndMethods(target));
+  let sourceKeys = _.keys(source).filter(filterPrivateAndMethods(source));
 
   // Find the keys to be removed
   diff.removed = _.difference(targetKeys, sourceKeys);
diff --git a/src/ui/public/utils/diff_time_picker_vals.js b/src/ui/public/utils/diff_time_picker_vals.js
index 5aa071f7932bd..43fcfcd5d38d6 100644
--- a/src/ui/public/utils/diff_time_picker_vals.js
+++ b/src/ui/public/utils/diff_time_picker_vals.js
@@ -2,7 +2,7 @@ import _ from 'lodash';
 import angular from 'angular';
 export default function DiffTimePickerValuesFn() {
 
-  var valueOf = function (o) {
+  let valueOf = function (o) {
     if (o) return o.valueOf();
   };
 
diff --git a/src/ui/public/utils/es_bool.js b/src/ui/public/utils/es_bool.js
index a3a9fa9206f89..a580ffac72188 100644
--- a/src/ui/public/utils/es_bool.js
+++ b/src/ui/public/utils/es_bool.js
@@ -1,5 +1,5 @@
 define(function () {
-  var map = {
+  let map = {
     'false': false,
     'off': false,
     'no': false,
@@ -11,7 +11,7 @@ define(function () {
   };
 
   return function (str) {
-    var bool = map[String(str)];
+    let bool = map[String(str)];
 
     if (typeof bool !== 'boolean') {
       throw new TypeError('"' + str + '" does not map to an esBool');
diff --git a/src/ui/public/utils/find_by_param.js b/src/ui/public/utils/find_by_param.js
index fdffd514046b7..60763f07f8478 100644
--- a/src/ui/public/utils/find_by_param.js
+++ b/src/ui/public/utils/find_by_param.js
@@ -3,7 +3,7 @@ import _ from 'lodash';
 // if the param is missing, return undefined
 export default function findByParam(values, param) {
   if (_.isArray(values)) { // point series chart
-    var index = _.findIndex(values, param);
+    let index = _.findIndex(values, param);
     if (index === -1) return;
     return values[index][param];
   }
diff --git a/src/ui/public/utils/ipv4_address.js b/src/ui/public/utils/ipv4_address.js
index d0c8fd3f5f29d..d8c396d02ab6b 100644
--- a/src/ui/public/utils/ipv4_address.js
+++ b/src/ui/public/utils/ipv4_address.js
@@ -1,6 +1,6 @@
 define(function () {
-  var NUM_BYTES = 4;
-  var BYTE_SIZE = 256;
+  let NUM_BYTES = 4;
+  let BYTE_SIZE = 256;
 
   function throwError(ipAddress) {
     throw Error('Invalid IPv4 address: ' + ipAddress);
@@ -19,11 +19,11 @@ define(function () {
     if (typeof ipAddress === 'string') {
       this.value = 0;
 
-      var bytes = ipAddress.split('.');
+      let bytes = ipAddress.split('.');
       if (bytes.length !== NUM_BYTES) throwError(ipAddress);
 
-      for (var i = 0; i < bytes.length; i++) {
-        var byte = Number(bytes[i]);
+      for (let i = 0; i < bytes.length; i++) {
+        let byte = Number(bytes[i]);
         if (!isIntegerInRange(byte, 0, BYTE_SIZE)) throwError(ipAddress);
         this.value += Math.pow(BYTE_SIZE, NUM_BYTES - 1 - i) * byte;
       }
@@ -33,9 +33,9 @@ define(function () {
   }
 
   Ipv4Address.prototype.toString = function () {
-    var value = this.value;
-    var bytes = [];
-    for (var i = 0; i < NUM_BYTES; i++) {
+    let value = this.value;
+    let bytes = [];
+    for (let i = 0; i < NUM_BYTES; i++) {
       bytes.unshift(value % 256);
       value = Math.floor(value / 256);
     }
diff --git a/src/ui/public/utils/lodash-mixins/collection.js b/src/ui/public/utils/lodash-mixins/collection.js
index 469821df0223f..dfcff7c8ad8dc 100644
--- a/src/ui/public/utils/lodash-mixins/collection.js
+++ b/src/ui/public/utils/lodash-mixins/collection.js
@@ -15,7 +15,7 @@ export default function (_) {
      * @return {array} - the objs argument
      */
     move: function (objs, obj, below, qualifier) {
-      var origI = _.isNumber(obj) ? obj : objs.indexOf(obj);
+      let origI = _.isNumber(obj) ? obj : objs.indexOf(obj);
       if (origI === -1) return objs;
 
       if (_.isNumber(below)) {
@@ -27,11 +27,11 @@ export default function (_) {
       below = !!below;
       qualifier = _.callback(qualifier);
 
-      var above = !below;
-      var finder = below ? _.findIndex : _.findLastIndex;
+      let above = !below;
+      let finder = below ? _.findIndex : _.findLastIndex;
 
       // find the index of the next/previous obj that meets the qualifications
-      var targetI = finder(objs, function (otherAgg, otherI) {
+      let targetI = finder(objs, function (otherAgg, otherI) {
         if (below && otherI <= origI) return;
         if (above && otherI >= origI) return;
         return !!qualifier(otherAgg, otherI);
@@ -58,8 +58,8 @@ export default function (_) {
      * @return {object}
      */
     organizeBy: function (collection, callback) {
-      var buckets = {};
-      var prop = typeof callback === 'function' ? false : callback;
+      let buckets = {};
+      let prop = typeof callback === 'function' ? false : callback;
 
       function add(key, obj) {
         if (!buckets[key]) buckets[key] = [];
@@ -67,14 +67,14 @@ export default function (_) {
       }
 
       _.each(collection, function (obj) {
-        var keys = prop === false ? callback(obj) : obj[prop];
+        let keys = prop === false ? callback(obj) : obj[prop];
 
         if (!_.isArray(keys)) {
           add(keys, obj);
           return;
         }
 
-        var length = keys.length;
+        let length = keys.length;
         while (length-- > 0) {
           add(keys[length], obj);
         }
@@ -108,14 +108,14 @@ export default function (_) {
      * @return {Array} dest
      */
     pushAll: function (source, dest) {
-      var start = dest.length;
-      var adding = source.length;
+      let start = dest.length;
+      let adding = source.length;
 
       // allocate - http://goo.gl/e2i0S0
       dest.length = start + adding;
 
       // fill sparse positions
-      var i = -1;
+      let i = -1;
       while (++i < adding) dest[start + i] = source[i];
 
       return dest;
diff --git a/src/ui/public/utils/lodash-mixins/function.js b/src/ui/public/utils/lodash-mixins/function.js
index c458a71b62d5e..5448baeae6dfd 100644
--- a/src/ui/public/utils/lodash-mixins/function.js
+++ b/src/ui/public/utils/lodash-mixins/function.js
@@ -13,11 +13,11 @@ export default function (_) {
      * @return {Function} - the wrapper method
      */
     onceWithCb: function (fn) {
-      var callbacks = [];
+      let callbacks = [];
 
       // on initial flush, call the init function, but ensure
       // that it only happens once
-      var flush = _.once(function (cntx, args) {
+      let flush = _.once(function (cntx, args) {
         args.push(function finishedOnce() {
           // override flush to simply schedule an asynchronous clear
           flush = function () {
@@ -33,8 +33,8 @@ export default function (_) {
       });
 
       return function runOnceWithCb() {
-        var args = [].slice.call(arguments, 0);
-        var cb = args[args.length - 1];
+        let args = [].slice.call(arguments, 0);
+        let cb = args[args.length - 1];
 
         if (typeof cb === 'function') {
           callbacks.push(cb);
diff --git a/src/ui/public/utils/lodash-mixins/object.js b/src/ui/public/utils/lodash-mixins/object.js
index 32b4a528d3c48..5add1b8880611 100644
--- a/src/ui/public/utils/lodash-mixins/object.js
+++ b/src/ui/public/utils/lodash-mixins/object.js
@@ -18,8 +18,8 @@ export default function (_) {
      * @return {object}
      */
     flattenWith: function (dot, nestedObj, flattenArrays) {
-      var stack = []; // track key stack
-      var flatObj = {};
+      let stack = []; // track key stack
+      let flatObj = {};
 
       (function flattenObj(obj) {
         _.keys(obj).forEach(function (key) {
diff --git a/src/ui/public/utils/lodash-mixins/oop.js b/src/ui/public/utils/lodash-mixins/oop.js
index 39c329dce81f6..e044d37bb21cd 100644
--- a/src/ui/public/utils/lodash-mixins/oop.js
+++ b/src/ui/public/utils/lodash-mixins/oop.js
@@ -11,10 +11,10 @@ export default function (_) {
     };
   }
 
-  var props = {
+  let props = {
     inherits: describeConst(function (SuperClass) {
 
-      var prototype = Object.create(SuperClass.prototype, {
+      let prototype = Object.create(SuperClass.prototype, {
         constructor: describeConst(this),
         superConstructor: describeConst(SuperClass)
       });
diff --git a/src/ui/public/utils/lodash-mixins/string.js b/src/ui/public/utils/lodash-mixins/string.js
index 4c9208c2322ba..e9225e5a13047 100644
--- a/src/ui/public/utils/lodash-mixins/string.js
+++ b/src/ui/public/utils/lodash-mixins/string.js
@@ -1,6 +1,6 @@
 export default function (_) {
 
-  var DOT_PREFIX_RE = /(.).+?\./g;
+  let DOT_PREFIX_RE = /(.).+?\./g;
 
   _.mixin({
 
@@ -39,10 +39,10 @@ export default function (_) {
     commaSeperatedList: function (input) {
       if (_.isArray(input)) return input;
 
-      var source = String(input || '').split(',');
-      var list = [];
+      let source = String(input || '').split(',');
+      let list = [];
       while (source.length) {
-        var item = source.shift().trim();
+        let item = source.shift().trim();
         if (item) list.push(item);
       }
 
diff --git a/src/ui/public/utils/mapping_setup.js b/src/ui/public/utils/mapping_setup.js
index 5ec4d28a69327..232fa5ff21072 100644
--- a/src/ui/public/utils/mapping_setup.js
+++ b/src/ui/public/utils/mapping_setup.js
@@ -2,9 +2,9 @@ import angular from 'angular';
 import _ from 'lodash';
 define(function () {
   return function MappingSetupService(kbnIndex, es) {
-    var mappingSetup = this;
+    let mappingSetup = this;
 
-    var json = {
+    let json = {
       _serialize: function (val) {
         if (val != null) return angular.toJson(val);
       },
@@ -16,14 +16,14 @@ define(function () {
     /**
      * Use to create the mappings, but that should only happen one at a time
      */
-    var activeTypeCreations = {};
+    let activeTypeCreations = {};
 
     /**
      * Get the list of type's mapped in elasticsearch
      * @return {[type]} [description]
      */
-    var getKnownKibanaTypes = _.once(function () {
-      var indexName = kbnIndex;
+    let getKnownKibanaTypes = _.once(function () {
+      let indexName = kbnIndex;
       return es.indices.getFieldMapping({
         // only concerned with types in this kibana index
         index: indexName,
@@ -70,13 +70,13 @@ define(function () {
         });
       }
 
-      var prom = getKnownKibanaTypes()
+      let prom = getKnownKibanaTypes()
       .then(function (knownTypes) {
         // if the type is in the knownTypes array already
         if (~knownTypes.indexOf(type)) return false;
 
         // we need to create the mapping
-        var body = {};
+        let body = {};
         body[type] = {
           properties: mapping
         };
diff --git a/src/ui/public/utils/no_white_space.js b/src/ui/public/utils/no_white_space.js
index 29c4392cc8f3d..c57cc58fcb95d 100644
--- a/src/ui/public/utils/no_white_space.js
+++ b/src/ui/public/utils/no_white_space.js
@@ -1,4 +1,4 @@
-var TAGS_WITH_WS = />\s+</g;
+let TAGS_WITH_WS = />\s+</g;
 
 /**
  * Remove all of the whitespace between html tags
diff --git a/src/ui/public/utils/obj_define.js b/src/ui/public/utils/obj_define.js
index 0084ae72bf692..664c6fcfb2168 100644
--- a/src/ui/public/utils/obj_define.js
+++ b/src/ui/public/utils/obj_define.js
@@ -9,7 +9,7 @@ function ObjDefine(defaults, prototype) {
 }
 
 ObjDefine.REDEFINE_SUPPORTED = (function () {
-  var a = Object.create(Object.prototype, {
+  let a = Object.create(Object.prototype, {
     prop: {
       configurable: true,
       value: 1
@@ -66,7 +66,7 @@ ObjDefine.prototype.comp = function (name, val) {
  * @return {object} - created object
  */
 ObjDefine.prototype.create = function () {
-  var self = this;
+  let self = this;
   self.obj = Object.create(this.prototype, self.descs);
 
   if (!ObjDefine.REDEFINE_SUPPORTED && !self.prototype.toJSON) {
@@ -76,7 +76,7 @@ ObjDefine.prototype.create = function () {
     // due to https://github.com/ariya/phantomjs/issues/11856
     self.obj.toJSON = function () {
       return _.transform(self.obj, function (json, val, key) {
-        var desc = self.descs[key];
+        let desc = self.descs[key];
         if (desc && desc.enumerable && val == null) return;
         json[key] = val;
       }, {});
@@ -97,8 +97,8 @@ ObjDefine.prototype._define = function (name, val, exported, changeable) {
 };
 
 ObjDefine.prototype._describe = function (name, val, exported, changeable) {
-  var self = this;
-  var exists = val != null;
+  let self = this;
+  let exists = val != null;
 
   if (exported && ObjDefine.REDEFINE_SUPPORTED) {
     return {
diff --git a/src/ui/public/utils/ordinal_suffix.js b/src/ui/public/utils/ordinal_suffix.js
index c7d14d437cff6..54038effa2bd9 100644
--- a/src/ui/public/utils/ordinal_suffix.js
+++ b/src/ui/public/utils/ordinal_suffix.js
@@ -5,12 +5,12 @@ export default function addOrdinalSuffix(num) {
 };
 
 function suffix(num) {
-  var int = Math.floor(parseFloat(num));
+  let int = Math.floor(parseFloat(num));
 
-  var hunth = int % 100;
+  let hunth = int % 100;
   if (hunth >= 11 && hunth <= 13) return 'th';
 
-  var tenth = int % 10;
+  let tenth = int % 10;
   if (tenth === 1) return 'st';
   if (tenth === 2) return 'nd';
   if (tenth === 3) return 'rd';
diff --git a/src/ui/public/utils/parse_interval.js b/src/ui/public/utils/parse_interval.js
index 1f46eaf6a33bf..9c81c730e10df 100644
--- a/src/ui/public/utils/parse_interval.js
+++ b/src/ui/public/utils/parse_interval.js
@@ -3,18 +3,18 @@ import moment from 'moment';
 import dateMath from 'ui/utils/date_math';
 
 // Assume interval is in the form (value)(unit), such as "1h"
-var INTERVAL_STRING_RE = new RegExp('^([0-9\\.]*)\\s*(' + dateMath.units.join('|') + ')$');
+let INTERVAL_STRING_RE = new RegExp('^([0-9\\.]*)\\s*(' + dateMath.units.join('|') + ')$');
 
 export default function parseInterval(interval) {
-  var matches = String(interval).trim().match(INTERVAL_STRING_RE);
+  let matches = String(interval).trim().match(INTERVAL_STRING_RE);
 
   if (!matches) return null;
 
   try {
-    var value = parseFloat(matches[1]) || 1;
-    var unit = matches[2];
+    let value = parseFloat(matches[1]) || 1;
+    let unit = matches[2];
 
-    var duration = moment.duration(value, unit);
+    let duration = moment.duration(value, unit);
 
     // There is an error with moment, where if you have a fractional interval between 0 and 1, then when you add that
     // interval to an existing moment object, it will remain unchanged, which causes problems in the ordered_x_keys
@@ -23,7 +23,7 @@ export default function parseInterval(interval) {
     // adding 0.5 days until we hit the end date. However, since there is a bug in moment, when you add 0.5 days to
     // the start date, you get the same exact date (instead of being ahead by 12 hours). So instead of returning
     // a duration corresponding to 0.5 hours, we return a duration corresponding to 12 hours.
-    var selectedUnit = _.find(dateMath.units, function (unit) {
+    let selectedUnit = _.find(dateMath.units, function (unit) {
       return Math.abs(duration.as(unit)) >= 1;
     });
 
diff --git a/src/ui/public/utils/query_string.js b/src/ui/public/utils/query_string.js
index df317284e0095..adf714cd64030 100644
--- a/src/ui/public/utils/query_string.js
+++ b/src/ui/public/utils/query_string.js
@@ -1,4 +1,4 @@
-var qs = {};
+let qs = {};
 
 /*****
 /*** orignally copied from angular, modified our purposes
@@ -37,7 +37,7 @@ function encodeUriQuery(val, pctEncodeSpaces) {
  * @returns {Object.<string,boolean|Array>}
  */
 qs.decode = function (keyValue) {
-  var obj = {};
+  let obj = {};
   let keyValueParts;
   let key;
 
@@ -46,7 +46,7 @@ qs.decode = function (keyValue) {
       keyValueParts = keyValue.split('=');
       key = tryDecodeURIComponent(keyValueParts[0]);
       if (key !== void 0) {
-        var val = keyValueParts[1] !== void 0 ? tryDecodeURIComponent(keyValueParts[1]) : true;
+        let val = keyValueParts[1] !== void 0 ? tryDecodeURIComponent(keyValueParts[1]) : true;
         if (!obj[key]) {
           obj[key] = val;
         } else if (Array.isArray(obj[key])) {
@@ -66,10 +66,10 @@ qs.decode = function (keyValue) {
  * @return {String}
  */
 qs.encode = function (obj) {
-  var parts = [];
-  var keys = Object.keys(obj).sort();
+  let parts = [];
+  let keys = Object.keys(obj).sort();
   keys.forEach(function (key) {
-    var value = obj[key];
+    let value = obj[key];
     if (Array.isArray(value)) {
       value.forEach(function (arrayValue) {
         parts.push(qs.param(key, arrayValue));
@@ -92,8 +92,8 @@ qs.param = function (key, val) {
  *                    the same if the url does not have a query string
  */
 qs.findInUrl = function (url) {
-  var qsStart = url.indexOf('?');
-  var hashStart = url.lastIndexOf('#');
+  let qsStart = url.indexOf('?');
+  let hashStart = url.lastIndexOf('#');
 
   if (hashStart === -1) {
     // out of bounds
@@ -111,8 +111,8 @@ qs.findInUrl = function (url) {
 };
 
 qs.replaceParamInUrl = function (url, param, newVal) {
-  var loc = qs.findInUrl(url);
-  var parsed = qs.decode(url.substring(loc.start + 1, loc.end));
+  let loc = qs.findInUrl(url);
+  let parsed = qs.decode(url.substring(loc.start + 1, loc.end));
 
   if (newVal != null) {
     parsed[param] = newVal;
@@ -120,7 +120,7 @@ qs.replaceParamInUrl = function (url, param, newVal) {
     delete parsed[param];
   }
 
-  var chars = url.split('');
+  let chars = url.split('');
   chars.splice(loc.start, loc.end - loc.start, '?' + qs.encode(parsed));
   return chars.join('');
 };
diff --git a/src/ui/public/utils/range.js b/src/ui/public/utils/range.js
index b272fdfa9ae01..dc34e4ab650e0 100644
--- a/src/ui/public/utils/range.js
+++ b/src/ui/public/utils/range.js
@@ -13,7 +13,7 @@ import _ from 'lodash';
  *
  * @type {String}
  */
-var _RE_NUMBER = '(\\-?(?:\\d+(?:\\.\\d+)?|Infinity))';
+let _RE_NUMBER = '(\\-?(?:\\d+(?:\\.\\d+)?|Infinity))';
 
 /**
  * Regexp for the interval notation
@@ -25,11 +25,11 @@ var _RE_NUMBER = '(\\-?(?:\\d+(?:\\.\\d+)?|Infinity))';
  *
  * @type {RegExp}
  */
-var RANGE_RE = new RegExp('^\\s*([\\[|\\(])\\s*' + _RE_NUMBER + '\\s*,\\s*' + _RE_NUMBER + '\\s*([\\]|\\)])\\s*$');
+let RANGE_RE = new RegExp('^\\s*([\\[|\\(])\\s*' + _RE_NUMBER + '\\s*,\\s*' + _RE_NUMBER + '\\s*([\\]|\\)])\\s*$');
 
 function parse(input) {
 
-  var match = String(input).match(RANGE_RE);
+  let match = String(input).match(RANGE_RE);
   if (!match) {
     throw new TypeError('expected input to be in interval notation eg. (100, 200]');
   }
@@ -43,7 +43,7 @@ function parse(input) {
 }
 
 function Range(/* minIncl, min, max, maxIncl */) {
-  var args = _.toArray(arguments);
+  let args = _.toArray(arguments);
   if (args[1] > args[2]) args.reverse();
 
   this.minInclusive = args[0];
diff --git a/src/ui/public/utils/rison.js b/src/ui/public/utils/rison.js
index c4932355e62fe..9489478e68e0b 100644
--- a/src/ui/public/utils/rison.js
+++ b/src/ui/public/utils/rison.js
@@ -1,6 +1,6 @@
 /* eslint-disable */
 define(function () {
-  var rison = {};
+  let rison = {};
   //////////////////////////////////////////////////
   //
   //  the stringifier is based on
@@ -39,11 +39,11 @@ define(function () {
   //rison.idchar_punctuation = "_-./~";
 
   (function () {
-      var l = [];
-      for (var hi = 0; hi < 16; hi++) {
-          for (var lo = 0; lo < 16; lo++) {
+      let l = [];
+      for (let hi = 0; hi < 16; hi++) {
+          for (let lo = 0; lo < 16; lo++) {
               if (hi+lo == 0) continue;
-              var c = String.fromCharCode(hi*16 + lo);
+              let c = String.fromCharCode(hi*16 + lo);
               if (! /\w|[-_.\/~]/.test(c))
                   l.push('\\u00' + hi.toString(16) + lo.toString(16));
           }
@@ -69,7 +69,7 @@ define(function () {
 
 
   (function () {
-      var idrx = '[^' + rison.not_idstart + rison.not_idchar +
+      let idrx = '[^' + rison.not_idstart + rison.not_idchar +
                  '][^' + rison.not_idchar + ']*';
 
       rison.id_ok = new RegExp('^' + idrx + '$');
@@ -110,17 +110,17 @@ define(function () {
   //
 
   (function () {
-      var sq = { // url-ok but quoted in strings
+      let sq = { // url-ok but quoted in strings
                  "'": true,  '!': true
       },
       enc = function (v) {
           if (v && typeof v.toJSON === 'function') v = v.toJSON();
-          var fn = s[typeof v];
+          let fn = s[typeof v];
           if (fn) return fn(v);
       },
       s = {
               array: function (x) {
-                  var a = ['!('], b, f, i, l = x.length, v;
+                  let a = ['!('], b, f, i, l = x.length, v;
                   for (i = 0; i < l; i += 1) {
                       v = enc(x[i]);
                       if (typeof v == 'string') {
@@ -154,7 +154,7 @@ define(function () {
                           return s.array(x);
                       }
 
-                      var a = ['('], b, f, i, v, ki, ks=[];
+                      let a = ['('], b, f, i, v, ki, ks=[];
                       for (i in x)
                           ks[ks.length] = i;
                       ks.sort();
@@ -212,7 +212,7 @@ define(function () {
       rison.encode_object = function (v) {
           if (typeof v != 'object' || v === null || v instanceof Array)
               throw new Error("rison.encode_object expects an object argument");
-          var r = s[typeof v](v);
+          let r = s[typeof v](v);
           return r.substring(1, r.length-1);
       };
 
@@ -223,7 +223,7 @@ define(function () {
       rison.encode_array = function (v) {
           if (!(v instanceof Array))
               throw new Error("rison.encode_array expects an array argument");
-          var r = s[typeof v](v);
+          let r = s[typeof v](v);
           return r.substring(2, r.length-1);
       };
 
@@ -259,8 +259,8 @@ define(function () {
    *     http://osteele.com/sources/openlaszlo/json
    */
   rison.decode = function(r) {
-      var errcb = function(e) { throw Error('rison decoder error: ' + e); };
-      var p = new rison.parser(errcb);
+      let errcb = function(e) { throw Error('rison decoder error: ' + e); };
+      let p = new rison.parser(errcb);
       return p.parse(r);
   };
 
@@ -315,7 +315,7 @@ define(function () {
       this.string = str;
       this.index = 0;
       this.message = null;
-      var value = this.readValue();
+      let value = this.readValue();
       if (!this.message && this.next())
           value = this.error("unable to parse string as rison: '" + rison.encode(str) + "'");
       if (this.message && this.errorHandler)
@@ -331,26 +331,26 @@ define(function () {
   }
 
   rison.parser.prototype.readValue = function () {
-      var c = this.next();
-      var fn = c && this.table[c];
+      let c = this.next();
+      let fn = c && this.table[c];
 
       if (fn)
           return fn.apply(this);
 
       // fell through table, parse as an id
 
-      var s = this.string;
-      var i = this.index-1;
+      let s = this.string;
+      let i = this.index-1;
 
       // Regexp.lastIndex may not work right in IE before 5.5?
       // g flag on the regexp is also necessary
       rison.next_id.lastIndex = i;
-      var m = rison.next_id.exec(s);
+      let m = rison.next_id.exec(s);
 
       // console.log('matched id', i, r.lastIndex);
 
       if (m.length > 0) {
-          var id = m[0];
+          let id = m[0];
           this.index = i+id.length;
           return id;  // a string
       }
@@ -360,7 +360,7 @@ define(function () {
   }
 
   rison.parser.parse_array = function (parser) {
-      var ar = [];
+      let ar = [];
       let c;
       while ((c = parser.next()) != ')') {
           if (!c) return parser.error("unmatched '!('");
@@ -371,7 +371,7 @@ define(function () {
               return parser.error("extra ','");
           } else
               --parser.index;
-          var n = parser.readValue();
+          let n = parser.readValue();
           if (typeof n == "undefined") return undefined;
           ar.push(n);
       }
@@ -387,10 +387,10 @@ define(function () {
 
   rison.parser.prototype.table = {
       '!': function () {
-          var s = this.string;
-          var c = s.charAt(this.index++);
+          let s = this.string;
+          let c = s.charAt(this.index++);
           if (!c) return this.error('"!" at end of input');
-          var x = rison.parser.bangs[c];
+          let x = rison.parser.bangs[c];
           if (typeof(x) == 'function') {
               return x.call(null, this);
           } else if (typeof(x) == 'undefined') {
@@ -399,9 +399,9 @@ define(function () {
           return x;
       },
       '(': function () {
-          var o = {};
+          let o = {};
           let c;
-          var count = 0;
+          let count = 0;
           while ((c = this.next()) != ')') {
               if (count) {
                   if (c != ',')
@@ -410,10 +410,10 @@ define(function () {
                   return this.error("extra ','");
               } else
                   --this.index;
-              var k = this.readValue();
+              let k = this.readValue();
               if (typeof k == "undefined") return undefined;
               if (this.next() != ':') return this.error("missing ':'");
-              var v = this.readValue();
+              let v = this.readValue();
               if (typeof v == "undefined") return undefined;
               o[k] = v;
               count++;
@@ -421,10 +421,10 @@ define(function () {
           return o;
       },
       "'": function () {
-          var s = this.string;
-          var i = this.index;
-          var start = i;
-          var segments = [];
+          let s = this.string;
+          let i = this.index;
+          let start = i;
+          let segments = [];
           let c;
           while ((c = s.charAt(i++)) != "'") {
               //if (i == s.length) return this.error('unmatched "\'"');
@@ -449,18 +449,18 @@ define(function () {
       // Also any digit.  The statement that follows this table
       // definition fills in the digits.
       '-': function () {
-          var s = this.string;
-          var i = this.index;
-          var start = i-1;
-          var state = 'int';
-          var permittedSigns = '-';
-          var transitions = {
+          let s = this.string;
+          let i = this.index;
+          let start = i-1;
+          let state = 'int';
+          let permittedSigns = '-';
+          let transitions = {
               'int+.': 'frac',
               'int+e': 'exp',
               'frac+e': 'exp'
           };
           do {
-              var c = s.charAt(i++);
+              let c = s.charAt(i++);
               if (!c) break;
               if ('0' <= c && c <= '9') continue;
               if (permittedSigns.indexOf(c) >= 0) {
@@ -478,17 +478,17 @@ define(function () {
   };
   // copy table['-'] to each of table[i] | i <- '0'..'9':
   (function (table) {
-      for (var i = 0; i <= 9; i++)
+      for (let i = 0; i <= 9; i++)
           table[String(i)] = table['-'];
   })(rison.parser.prototype.table);
 
   // return the next non-whitespace character, or undefined
   rison.parser.prototype.next = function () {
-      var s = this.string;
-      var i = this.index;
+      let s = this.string;
+      let i = this.index;
       do {
           if (i == s.length) return undefined;
-          var c = s.charAt(i++);
+          let c = s.charAt(i++);
       } while (rison.parser.WHITESPACE.indexOf(c) >= 0);
       this.index = i;
       return c;
diff --git a/src/ui/public/utils/sequencer.js b/src/ui/public/utils/sequencer.js
index 15be808dd0022..5656890c8f101 100644
--- a/src/ui/public/utils/sequencer.js
+++ b/src/ui/public/utils/sequencer.js
@@ -1,18 +1,18 @@
 import _ from 'lodash';
 
 function create(min, max, length, mod) {
-  var seq = new Array(length);
+  let seq = new Array(length);
 
-  var valueDist = max - min;
+  let valueDist = max - min;
 
   // range of values that the mod creates
-  var modRange = [mod(0, length), mod(length - 1, length)];
+  let modRange = [mod(0, length), mod(length - 1, length)];
 
   // distance between
-  var modRangeDist = modRange[1] - modRange[0];
+  let modRangeDist = modRange[1] - modRange[0];
 
   _.times(length, function (i) {
-    var modIPercent = (mod(i, length) - modRange[0]) / modRangeDist;
+    let modIPercent = (mod(i, length) - modRange[0]) / modRangeDist;
 
     // percent applied to distance and added to min to
     // produce value
@@ -80,8 +80,8 @@ export default {
     // adapted from output of http://www.timotheegroleau.com/Flash/experiments/easing_function_generator.htm
     // generates numbers from 0 to 100
 
-    var ts = (i /= length) * i;
-    var tc = ts * i;
+    let ts = (i /= length) * i;
+    let tc = ts * i;
     return 100 * (
       0.5 * tc * ts +
       -3 * ts * ts +
diff --git a/src/ui/public/utils/simple_emitter.js b/src/ui/public/utils/simple_emitter.js
index 20cc5569b8a8b..f9a6f69a24eee 100644
--- a/src/ui/public/utils/simple_emitter.js
+++ b/src/ui/public/utils/simple_emitter.js
@@ -20,7 +20,7 @@ function SimpleEmitter() {
  * @return {SimpleEmitter} - this, for chaining
  */
 SimpleEmitter.prototype.on = function (name, handler) {
-  var handlers = this._listeners[name];
+  let handlers = this._listeners[name];
   if (!handlers) handlers = this._listeners[name] = [];
 
   handlers.push(handler);
@@ -68,8 +68,8 @@ SimpleEmitter.prototype.removeAllListeners = function () {
  */
 SimpleEmitter.prototype.emit = _.restParam(function (name, args) {
   if (!this._listeners[name]) return this;
-  var listeners = this.listeners(name);
-  var i = -1;
+  let listeners = this.listeners(name);
+  let i = -1;
 
   while (++i < listeners.length) {
     listeners[i].apply(this, args);
diff --git a/src/ui/public/utils/slugify_id.js b/src/ui/public/utils/slugify_id.js
index 3cc4366a53964..b0f1920e501e6 100644
--- a/src/ui/public/utils/slugify_id.js
+++ b/src/ui/public/utils/slugify_id.js
@@ -2,14 +2,14 @@ import _ from 'lodash';
 export default function (id) {
   if (id == null) return;
 
-  var trans = {
+  let trans = {
     '/' : '-slash-',
     '\\?' : '-questionmark-',
     '\\&' : '-ampersand-',
     '=' : '-equal-'
   };
   _.each(trans, function (val, key) {
-    var regex = new RegExp(key, 'g');
+    let regex = new RegExp(key, 'g');
     id = id.replace(regex, val);
   });
   id = id.replace(/[\s]+/g, '-');
diff --git a/src/ui/public/utils/supports.js b/src/ui/public/utils/supports.js
index 3e99b42da0104..cf8cd4835c65f 100644
--- a/src/ui/public/utils/supports.js
+++ b/src/ui/public/utils/supports.js
@@ -5,14 +5,14 @@ import _ from 'lodash';
  */
 export default {
   cssFilters: (function () {
-    var e = document.createElement('img');
-    var rules = ['webkitFilter', 'mozFilter', 'msFilter', 'filter'];
-    var test = 'grayscale(1)';
+    let e = document.createElement('img');
+    let rules = ['webkitFilter', 'mozFilter', 'msFilter', 'filter'];
+    let test = 'grayscale(1)';
     rules.forEach(function (rule) { e.style[rule] = test; });
 
     document.body.appendChild(e);
-    var styles = window.getComputedStyle(e);
-    var can = _(styles).pick(rules).includes(test);
+    let styles = window.getComputedStyle(e);
+    let can = _(styles).pick(rules).includes(test);
     document.body.removeChild(e);
 
     return can;
diff --git a/src/ui/public/vis/agg_config.js b/src/ui/public/vis/agg_config.js
index 8e5f76772931d..ab6c649bce58b 100644
--- a/src/ui/public/vis/agg_config.js
+++ b/src/ui/public/vis/agg_config.js
@@ -1,10 +1,10 @@
 import _ from 'lodash';
 import RegistryFieldFormatsProvider from 'ui/registry/field_formats';
 export default function AggConfigFactory(Private, fieldTypeFilter) {
-  var fieldFormats = Private(RegistryFieldFormatsProvider);
+  let fieldFormats = Private(RegistryFieldFormatsProvider);
 
   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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
    * @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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
    * @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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
       }
 
       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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
    * @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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
       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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
    * @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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
    */
   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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
   };
 
   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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
     }
 
     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 @@ export default function AggConfigFactory(Private, fieldTypeFilter) {
   };
 
   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/agg_config_result.js b/src/ui/public/vis/agg_config_result.js
index b7dac72820efa..4df97b55477c6 100644
--- a/src/ui/public/vis/agg_config_result.js
+++ b/src/ui/public/vis/agg_config_result.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/agg_configs.js b/src/ui/public/vis/agg_configs.js
index a112144ba803e..08f6798b7b2e5 100644
--- a/src/ui/public/vis/agg_configs.js
+++ b/src/ui/public/vis/agg_configs.js
@@ -3,13 +3,13 @@ import IndexedArray from 'ui/indexed_array';
 import VisAggConfigProvider from 'ui/vis/agg_config';
 import AggTypesIndexProvider from 'ui/agg_types/index';
 export default function AggConfigsFactory(Private) {
-  var AggConfig = Private(VisAggConfigProvider);
+  let AggConfig = Private(VisAggConfigProvider);
 
   AggConfig.aggTypes = Private(AggTypesIndexProvider);
 
   _.class(AggConfigs).inherits(IndexedArray);
   function AggConfigs(vis, configStates) {
-    var self = this;
+    let self = this;
     self.vis = vis;
 
     configStates = AggConfig.ensureIds(configStates || []);
@@ -36,9 +36,9 @@ export default function AggConfigsFactory(Private) {
       })
       .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));
           });
         }
@@ -48,7 +48,7 @@ export default function AggConfigsFactory(Private) {
   }
 
   AggConfigs.prototype.toDsl = function () {
-    var dslTopLvl = {};
+    let dslTopLvl = {};
     let dslLvlCursor;
     let nestedMetrics;
 
@@ -76,8 +76,8 @@ export default function AggConfigsFactory(Private) {
         // 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
@@ -85,7 +85,7 @@ export default function AggConfigsFactory(Private) {
         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) {
@@ -122,7 +122,7 @@ export default function AggConfigsFactory(Private) {
    */
   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;
     }, []);
   };
@@ -137,7 +137,7 @@ export default function AggConfigsFactory(Private) {
    */
   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/schemas.js b/src/ui/public/vis/schemas.js
index 3eeea29d6be73..f35c1a6d1324d 100644
--- a/src/ui/public/vis/schemas.js
+++ b/src/ui/public/vis/schemas.js
@@ -2,10 +2,10 @@ import _ from 'lodash';
 import IndexedArray from 'ui/indexed_array';
 import AggTypesAggParamsProvider from 'ui/agg_types/agg_params';
 export default function VisTypeSchemasFactory(Private) {
-  var AggParams = Private(AggTypesAggParamsProvider);
+  let AggParams = Private(AggTypesAggParamsProvider);
 
   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 fd7d5fda72823..dbf29fe416429 100644
--- a/src/ui/public/vis/vis.js
+++ b/src/ui/public/vis/vis.js
@@ -3,11 +3,11 @@ import AggTypesIndexProvider from 'ui/agg_types/index';
 import RegistryVisTypesProvider from 'ui/registry/vis_types';
 import VisAggConfigsProvider from 'ui/vis/agg_configs';
 export default function VisFactory(Notifier, Private) {
-  var aggTypes = Private(AggTypesIndexProvider);
-  var visTypes = Private(RegistryVisTypesProvider);
-  var AggConfigs = Private(VisAggConfigsProvider);
+  let aggTypes = Private(AggTypesIndexProvider);
+  let visTypes = Private(RegistryVisTypesProvider);
+  let AggConfigs = Private(VisAggConfigsProvider);
 
-  var notify = new Notifier({
+  let notify = new Notifier({
     location: 'Vis'
   });
 
@@ -31,10 +31,10 @@ export default function VisFactory(Notifier, Private) {
       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');
@@ -42,12 +42,12 @@ export default function VisFactory(Notifier, Private) {
       }
 
       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;
@@ -118,7 +118,7 @@ export default function VisFactory(Notifier, Private) {
   };
 
   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/vis_type.js b/src/ui/public/vis/vis_type.js
index 7df7eca820c6a..96ed7e1d2a00d 100644
--- a/src/ui/public/vis/vis_type.js
+++ b/src/ui/public/vis/vis_type.js
@@ -1,7 +1,7 @@
 import VisSchemasProvider from 'ui/vis/schemas';
 
 export default function VisTypeFactory(Private) {
-  var VisTypeSchemas = Private(VisSchemasProvider);
+  let VisTypeSchemas = Private(VisSchemasProvider);
 
   function VisType(opts) {
     opts = opts || {};
diff --git a/src/ui/public/vislib_vis_type/build_chart_data.js b/src/ui/public/vislib_vis_type/build_chart_data.js
index 8b584653ada63..84f2fc5875f42 100644
--- a/src/ui/public/vislib_vis_type/build_chart_data.js
+++ b/src/ui/public/vislib_vis_type/build_chart_data.js
@@ -2,23 +2,23 @@ import AggResponseIndexProvider from 'ui/agg_response/index';
 import AggResponseTabifyTableProvider from 'ui/agg_response/tabify/_table';
 
 export default function VislibVisBuildChartData(Private) {
-  var aggResponse = Private(AggResponseIndexProvider);
-  var Table = Private(AggResponseTabifyTableProvider);
+  let aggResponse = Private(AggResponseIndexProvider);
+  let Table = Private(AggResponseTabifyTableProvider);
 
   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
@@ -31,11 +31,11 @@ export default function VislibVisBuildChartData(Private) {
   };
 
   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;
@@ -44,13 +44,13 @@ export default function VislibVisBuildChartData(Private) {
     }
 
     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/vislib_vis_type/vislib_renderbot.js b/src/ui/public/vislib_vis_type/vislib_renderbot.js
index 956a61a7047ef..1cbbf1a424c21 100644
--- a/src/ui/public/vislib_vis_type/vislib_renderbot.js
+++ b/src/ui/public/vislib_vis_type/vislib_renderbot.js
@@ -3,9 +3,9 @@ import VislibProvider from 'ui/vislib';
 import VisRenderbotProvider from 'ui/vis/renderbot';
 import VislibVisTypeBuildChartDataProvider from 'ui/vislib_vis_type/build_chart_data';
 module.exports = function VislibRenderbotFactory(Private) {
-  var vislib = Private(VislibProvider);
-  var Renderbot = Private(VisRenderbotProvider);
-  var buildChartData = Private(VislibVisTypeBuildChartDataProvider);
+  let vislib = Private(VislibProvider);
+  let Renderbot = Private(VisRenderbotProvider);
+  let buildChartData = Private(VislibVisTypeBuildChartDataProvider);
 
   _.class(VislibRenderbot).inherits(Renderbot);
   function VislibRenderbot(vis, $el, uiState) {
@@ -14,7 +14,7 @@ module.exports = function VislibRenderbotFactory(Private) {
   }
 
   VislibRenderbot.prototype._createVis = function () {
-    var self = this;
+    let self = this;
 
     if (self.vislibVis) self.destroy();
 
@@ -29,7 +29,7 @@ module.exports = function VislibRenderbotFactory(Private) {
   };
 
   VislibRenderbot.prototype._getVislibParams = function () {
-    var self = this;
+    let self = this;
 
     return _.assign(
       {},
@@ -50,9 +50,9 @@ 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);
@@ -62,10 +62,10 @@ 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/vislib_vis_type.js b/src/ui/public/vislib_vis_type/vislib_vis_type.js
index c3c090f3bdfff..a18977bc2ca73 100644
--- a/src/ui/public/vislib_vis_type/vislib_vis_type.js
+++ b/src/ui/public/vislib_vis_type/vislib_vis_type.js
@@ -9,10 +9,10 @@ import AggResponsePointSeriesPointSeriesProvider from 'ui/agg_response/point_ser
 import VislibVisTypeVislibRenderbotProvider from 'ui/vislib_vis_type/vislib_renderbot';
 export default function VislibVisTypeFactory(Private) {
 
-  var VisTypeSchemas = Private(VisSchemasProvider);
-  var VisType = Private(VisVisTypeProvider);
-  var pointSeries = Private(AggResponsePointSeriesPointSeriesProvider);
-  var VislibRenderbot = Private(VislibVisTypeVislibRenderbotProvider);
+  let VisTypeSchemas = Private(VisSchemasProvider);
+  let VisType = Private(VisVisTypeProvider);
+  let pointSeries = Private(AggResponsePointSeriesPointSeriesProvider);
+  let VislibRenderbot = Private(VislibVisTypeVislibRenderbotProvider);
 
 
   _.class(VislibVisType).inherits(VisType);
diff --git a/src/ui/public/visualize/spy.js b/src/ui/public/visualize/spy.js
index 8b91ed0d0a77e..e8df7aa336b80 100644
--- a/src/ui/public/visualize/spy.js
+++ b/src/ui/public/visualize/spy.js
@@ -7,16 +7,16 @@ uiModules
   .get('app/visualize')
   .directive('visualizeSpy', function (Private, $compile) {
 
-    var spyModes = Private(RegistrySpyModesProvider);
-    var defaultMode = spyModes.inOrder[0].name;
+    let spyModes = Private(RegistrySpyModesProvider);
+    let defaultMode = spyModes.inOrder[0].name;
 
     return {
       restrict: 'E',
       template: spyTemplate,
       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 || {};
 
@@ -30,8 +30,8 @@ uiModules
           };
         }
 
-        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) {
@@ -57,7 +57,7 @@ uiModules
         };
 
         $scope.toggleDisplay = function () {
-          var modeName = _.get($scope.spy, 'mode.name');
+          let modeName = _.get($scope.spy, 'mode.name');
           $scope.setSpyMode(modeName ? null : defaultMode);
         };
 
@@ -74,7 +74,7 @@ uiModules
 
         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', () => $scope.uiState.off('change', syncUIState));
         }
@@ -85,7 +85,7 @@ uiModules
           'spy.mode.fill'
         ], function (newVals, oldVals) {
           // update the ui state, but only if it really changes
-          var changedVals = newVals.filter((val) => !_.isUndefined(val)).length > 0;
+          let changedVals = newVals.filter((val) => !_.isUndefined(val)).length > 0;
           if (changedVals && !_.isEqual(newVals, oldVals)) {
             if ($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 8b02f5d6fb5bd..86c9a5beae6be 100644
--- a/src/ui/public/visualize/visualize.js
+++ b/src/ui/public/visualize/visualize.js
@@ -11,9 +11,9 @@ uiModules
 .directive('visualize', function (Notifier, SavedVis, indexPatterns, Private, config, $timeout) {
 
 
-  var visTypes = Private(RegistryVisTypesProvider);
+  let visTypes = Private(RegistryVisTypesProvider);
 
-  var notify = new Notifier({
+  let notify = new Notifier({
     location: 'Visualize'
   });
 
@@ -30,7 +30,7 @@ uiModules
     template: visualizeTemplate,
     link: function ($scope, $el, attr) {
       let chart; // set in "vis" watcher
-      var minVisChartHeight = 180;
+      let minVisChartHeight = 180;
 
       if (_.isUndefined($scope.showSpyPanel)) {
         $scope.showSpyPanel = true;
@@ -38,19 +38,19 @@ uiModules
 
       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);
       };
@@ -58,9 +58,9 @@ uiModules
       $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));
 
@@ -73,8 +73,8 @@ uiModules
 
       // 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);
@@ -92,14 +92,14 @@ uiModules
         };
       }());
 
-      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)
@@ -116,7 +116,7 @@ uiModules
       });
 
       $scope.$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 36cd344bd89e3..b5a414f081608 100644
--- a/src/ui/public/visualize/visualize_legend.js
+++ b/src/ui/public/visualize/visualize_legend.js
@@ -11,16 +11,16 @@ import uiModules from 'ui/modules';
 
 uiModules.get('kibana')
 .directive('visualizeLegend', function (Private, getAppState) {
-  var Data = Private(VislibLibDataProvider);
-  var colorPalette = Private(VislibComponentsColorColorProvider);
-  var filterBarClickHandler = Private(FilterBarFilterBarClickHandlerProvider);
+  let Data = Private(VislibLibDataProvider);
+  let colorPalette = Private(VislibComponentsColorColorProvider);
+  let filterBarClickHandler = Private(FilterBarFilterBarClickHandlerProvider);
 
   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) {
@@ -30,29 +30,29 @@ uiModules.get('kibana')
       });
 
       $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);
       };
@@ -62,7 +62,7 @@ uiModules.get('kibana')
       };
 
       $scope.canFilter = function (legendData) {
-        var filters = clickHandler({point: legendData}, true) || [];
+        let filters = clickHandler({point: legendData}, true) || [];
         return filters.length;
       };
 
@@ -77,7 +77,7 @@ uiModules.get('kibana')
       ];
 
       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;
@@ -96,7 +96,7 @@ uiModules.get('kibana')
       };
 
       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 5cfa391068572..279076eea4e8b 100644
--- a/src/ui/public/watch_multi/watch_multi.js
+++ b/src/ui/public/watch_multi/watch_multi.js
@@ -37,15 +37,15 @@ uiModules.get('kibana')
       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 @@ uiModules.get('kibana')
 
       // 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 @@ uiModules.get('kibana')
 
     function normalizeExpression($scope, expr) {
       if (!expr) return;
-      var norm = {
+      let norm = {
         fn: $scope.$watch,
         deep: false
       };