Backport PR #6921

---------

**Commit 1:**
[internal] Replace var with let in ui/public U-W (no utils/vislib)

This change was applied to any .js files under directories beginning
with `u` through `w` (other than utils and vislib) in src/ui/public.
There are no `y` or `z` directories. The utils directory isn't included
because the generic change breaks something in it. The vislib directory
isn't included because it had too many changes on its own.

This was an automatic replacement from var to let for any variable
declaration that doubles as the initial assignment. Ultimately we want
most of these to be converted to const, but this commit is so large that
it warrants breaking each step of automation up into its own commit.

For example:

`var foo = 'bar';` becomes `let foo = 'var';`

This was accomplished by replacing:
find: `var ([a-zA-Z_$][0-9a-zA-Z_$]*)(\s+)=`
replace: `let $1$2=`

* Original sha: 80a733f
* Authored by Court Ewing <court@epixa.com> on 2016-04-14T14:13:22Z

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;
     };
 

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;

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;
 
@@ -75,16 +75,16 @@ 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
           // sub aggs
           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;

src/ui/public/Vis/Renderbot.js

@@ -1,5 +1,5 @@
 define(function (require) {
-  var _ = require('lodash');
+  let _ = require('lodash');
 
   return function RenderbotFactory(Private) {
 

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) {

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'
     });
 
@@ -29,23 +29,23 @@ 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');
           return;
         }
 
         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;

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 || {};