Enforce const usage in module scope only.

.jscsrc

@@ -2,6 +2,7 @@
   "esnext": true,
   "excludeFiles": ["ember-runtime/ext/rsvp.js"],
   "additionalRules": [ "lib/jscs-rules/*.js" ],
+  "disallowConstOutsideModuleScope": true,
   "disallowSpacesInsideArrayBrackets": "all",
   "disallowMultipleVarDeclWithAssignment": true,
   "disallowPaddingNewlinesInBlocks": true,

lib/jscs-rules/disallow-const-outside-module-scope.js

@@ -0,0 +1,38 @@
+var assert = require('assert');
+
+module.exports = function() { };
+
+module.exports.prototype = {
+  configure: function(option) {
+    assert(option === true, this.getOptionName() + ' requires a true value');
+  },
+
+  getOptionName: function() {
+    return 'disallowConstOutsideModuleScope';
+  },
+
+  check: function(file, errors) {
+    file.iterateNodesByType('VariableDeclaration', function(node) {
+      if (node.parentNode.type === 'Program') {
+        // declaration is in root of module
+        return;
+      }
+
+      if (node.parentNode.type === 'ExportNamedDeclaration' && node.parentNode.parentNode.type === 'Program') {
+        // declaration is a `export const foo = 'asdf'` in root of the module
+        return;
+      }
+
+      for (var i = 0; i < node.declarations.length; i++) {
+        var thisDeclaration = node.declarations[i];
+
+        if (thisDeclaration.parentNode.kind === 'const') {
+          errors.add(
+            '`const` should only be used in module scope (not inside functions/blocks).',
+            node.loc.start
+          );
+        }
+      }
+    });
+  }
+};

packages/container/tests/container_test.js

@@ -537,11 +537,11 @@ if (isEnabled('ember-container-inject-owner')) {
   });
 } else {
   QUnit.test('A `container` property is appended to every instantiated object', function() {
-    const registry = new Registry();
-    const container = registry.container();
-    const PostController = factory();
+    let registry = new Registry();
+    let container = registry.container();
+    let PostController = factory();
     registry.register('controller:post', PostController);
-    const postController = container.lookup('controller:post');
+    let postController = container.lookup('controller:post');
 
     strictEqual(postController.container, container, '');
   });

packages/container/tests/test-helpers/build-owner.js

@@ -7,9 +7,10 @@ export default function buildOwner(props) {
   let Owner = EmberObject.extend(RegistryProxy, ContainerProxy, {
     init() {
       this._super(...arguments);
-      const registry = this.__registry__ = new Registry();
+      let registry = this.__registry__ = new Registry();
       this.__container__ = registry.container({ owner: this });
     }
   });
+
   return Owner.create(props);
 }

packages/ember-htmlbars/lib/hooks/has-helper.js

@@ -5,7 +5,7 @@ export default function hasHelperHook(env, scope, helperName) {
     return true;
   }
 
-  const owner = env.owner;
+  let owner = env.owner;
   if (validateLazyHelperName(helperName, owner, env.hooks.keywords)) {
     var registrationName = 'helper:' + helperName;
     if (owner.hasRegistration(registrationName)) {

packages/ember-htmlbars/lib/keywords/closure-component.js

@@ -64,7 +64,7 @@ function createClosureComponentCell(env, originalComponentPath, params, hash, la
 }
 
 function isValidComponentPath(env, path) {
-  const result = lookupComponent(env.owner, path);
+  let result = lookupComponent(env.owner, path);
 
   return !!(result.component || result.layout);
 }

packages/ember-htmlbars/lib/keywords/get.js

@@ -15,8 +15,8 @@ import {
 } from 'ember-metal/observer';
 
 function labelFor(source, key) {
-  const sourceLabel = source.label ? source.label : '';
-  const keyLabel = key.label ? key.label : '';
+  let sourceLabel = source.label ? source.label : '';
+  let keyLabel = key.label ? key.label : '';
   return `(get ${sourceLabel} ${keyLabel})`;
 }
 
@@ -34,7 +34,7 @@ let DynamicKeyStream = BasicStream.extend({
   },
 
   key() {
-    const key = this.keyDep.getValue();
+    let key = this.keyDep.getValue();
     if (typeof key === 'string') {
       return key;
     }
@@ -84,12 +84,12 @@ let DynamicKeyStream = BasicStream.extend({
 });
 
 const buildStream = function buildStream(params) {
-  const [objRef, pathRef] = params;
+  let [objRef, pathRef] = params;
 
   assert('The first argument to {{get}} must be a stream', isStream(objRef));
   assert('{{get}} requires at least two arguments', params.length > 1);
 
-  const stream = buildDynamicKeyStream(objRef, pathRef);
+  let stream = buildDynamicKeyStream(objRef, pathRef);
 
   return stream;
 };

packages/ember-htmlbars/lib/node-managers/component-node-manager.js

@@ -236,7 +236,7 @@ export function createComponent(_component, isAngleBracket, props, renderNode, e
   props.renderer = props.parentView ? props.parentView.renderer : env.owner.lookup('renderer:-dom');
   props._viewRegistry = props.parentView ? props.parentView._viewRegistry : env.owner.lookup('-view-registry:main');
 
-  const component = _component.create(props);
+  let component = _component.create(props);
 
   // for the fallback case
   if (!getOwner(component)) {

packages/ember-htmlbars/lib/node-managers/view-node-manager.js

@@ -182,7 +182,7 @@ export function createOrUpdateComponent(component, options, createOptions, rende
 
     mergeBindings(props, snapshot);
 
-    const owner = options.parentView ? getOwner(options.parentView) : env.owner;
+    let owner = options.parentView ? getOwner(options.parentView) : env.owner;
 
     setOwner(props, owner);
     props.renderer = options.parentView ? options.parentView.renderer : owner && owner.lookup('renderer:-dom');

packages/ember-htmlbars/lib/system/lookup-helper.js

@@ -36,7 +36,7 @@ export function findHelper(name, view, env) {
   var helper = env.helpers[name];
 
   if (!helper) {
-    const owner = env.owner;
+    let owner = env.owner;
     if (validateLazyHelperName(name, owner, env.hooks.keywords)) {
       var helperName = 'helper:' + name;
       if (owner.hasRegistration(helperName)) {

packages/ember-htmlbars/lib/utils/extract-positional-params.js

@@ -11,7 +11,7 @@ export default function extractPositionalParams(renderNode, component, params, a
 }
 
 export function processPositionalParams(renderNode, positionalParams, params, attrs) {
-  const isNamed = typeof positionalParams === 'string';
+  let isNamed = typeof positionalParams === 'string';
 
   if (isNamed) {
     processRestPositionalParameters(renderNode, positionalParams, params, attrs);

packages/ember-htmlbars/lib/utils/is-component.js

@@ -15,7 +15,7 @@ import { isStream } from 'ember-metal/streams/utils';
  name was found in the container.
 */
 export default function isComponent(env, scope, path) {
-  const owner = env.owner;
+  let owner = env.owner;
   if (!owner) { return false; }
   if (typeof path === 'string') {
     if (CONTAINS_DOT_CACHE.get(path)) {

packages/ember-htmlbars/tests/compat/view_helper_test.js

@@ -36,7 +36,7 @@ QUnit.module('ember-htmlbars: compat - view helper', {
 });
 
 QUnit.test('using the view helper fails assertion', function(assert) {
-  const ViewClass = EmberView.extend({
+  let ViewClass = EmberView.extend({
     template: compile('fooView')
   });
   owner.register('view:foo', ViewClass);
@@ -67,7 +67,7 @@ QUnit.module('ember-htmlbars: compat - view helper [LEGACY]', {
 });
 
 QUnit.test('using the view helper with a string (inline form) fails assertion [LEGACY]', function(assert) {
-  const ViewClass = EmberView.extend({
+  let ViewClass = EmberView.extend({
     template: compile('fooView')
   });
   owner.register('view:foo', ViewClass);
@@ -85,7 +85,7 @@ QUnit.test('using the view helper with a string (inline form) fails assertion [L
 });
 
 QUnit.test('using the view helper with a string (block form) fails assertion [LEGACY]', function(assert) {
-  const ViewClass = EmberView.extend({
+  let ViewClass = EmberView.extend({
     template: compile('Foo says: {{yield}}')
   });
   owner.register('view:foo', ViewClass);

packages/ember-htmlbars/tests/glimmer-component/render-test.js

@@ -48,7 +48,7 @@ function renderComponent(tag, component) {
     .map(key => `${key}=${hash[key]}`)
     .join(' ');
 
-  const owner = buildOwner();
+  let owner = buildOwner();
   owner.register('component-lookup:main', ComponentLookup);
   owner.register(`component:${tag}`, implementation);
 

packages/ember-htmlbars/tests/integration/component_invocation_test.js

@@ -32,7 +32,7 @@ function commonTeardown() {
 }
 
 function appendViewFor(template, hash={}) {
-  const view = EmberView.extend({
+  let view = EmberView.extend({
     [OWNER]: owner,
     template: compile(template)
   }).create(hash);

packages/ember-htmlbars/tests/system/lookup-helper_test.js

@@ -14,7 +14,7 @@ function generateEnv(helpers, owner) {
 }
 
 function generateOwner() {
-  const owner = buildOwner();
+  let owner = buildOwner();
 
   owner.register('component-lookup:main', ComponentLookup);
 
@@ -58,7 +58,7 @@ QUnit.test('does not lookup in the container if the name does not contain a dash
 });
 
 QUnit.test('does a lookup in the container if the name contains a dash (and helper is not found in env)', function() {
-  const owner = generateOwner();
+  let owner = generateOwner();
   var env = generateEnv(null, owner);
   var view = {
     [OWNER]: owner
@@ -73,7 +73,7 @@ QUnit.test('does a lookup in the container if the name contains a dash (and help
 });
 
 QUnit.test('does a lookup in the container if the name is found in knownHelpers', function() {
-  const owner = generateOwner();
+  let owner = generateOwner();
   var env = generateEnv(null, owner);
   var view = {
     [OWNER]: owner
@@ -90,7 +90,7 @@ QUnit.test('does a lookup in the container if the name is found in knownHelpers'
 
 QUnit.test('looks up a shorthand helper in the container', function() {
   expect(2);
-  const owner = generateOwner();
+  let owner = generateOwner();
   var env = generateEnv(null, owner);
   var view = {
     [OWNER]: owner
@@ -113,7 +113,7 @@ QUnit.test('looks up a shorthand helper in the container', function() {
 
 QUnit.test('fails with a useful error when resolving a function', function() {
   expect(1);
-  const owner = generateOwner();
+  let owner = generateOwner();
   var env = generateEnv(null, owner);
   var view = {
     [OWNER]: owner

packages/ember-htmlbars/tests/utils.js

@@ -6,7 +6,7 @@ function registerAstPlugin(plugin) {
 }
 
 function removeAstPlugin(plugin) {
-  const index = plugins['ast'].indexOf(plugin);
+  let index = plugins['ast'].indexOf(plugin);
   plugins['ast'].splice(index, 1);
 }
 

packages/ember-metal/lib/injected_property.js

@@ -25,7 +25,7 @@ function InjectedProperty(type, name) {
 
 function injectedPropertyGet(keyName) {
   var desc = this[keyName];
-  const owner = getOwner(this);
+  let owner = getOwner(this);
 
   assert(`InjectedProperties should be defined with the Ember.inject computed property macros.`, desc && desc.isDescriptor && desc.type);
   assert(`Attempting to lookup an injected property on an object without a container, ensure that the object was instantiated via a container.`, owner);

packages/ember-routing-htmlbars/tests/helpers/closure_action_test.js

@@ -120,10 +120,10 @@ QUnit.test('action should be called on the correct scope', function(assert) {
 QUnit.test('arguments to action are passed, curry', function(assert) {
   assert.expect(4);
 
-  const first = 'mitch';
-  const second =  'martin';
-  const third = 'matt';
-  const fourth = 'wacky wycats';
+  let first = 'mitch';
+  let second =  'martin';
+  let third = 'matt';
+  let fourth = 'wacky wycats';
 
   innerComponent = EmberComponent.extend({
     fireAction() {
@@ -155,7 +155,7 @@ QUnit.test('arguments to action are passed, curry', function(assert) {
 QUnit.test('arguments to action are bound', function(assert) {
   assert.expect(1);
 
-  const value = 'lazy leah';
+  let value = 'lazy leah';
 
   innerComponent = EmberComponent.extend({
     fireAction() {
@@ -186,9 +186,9 @@ QUnit.test('arguments to action are bound', function(assert) {
 QUnit.test('array arguments are passed correctly to action', function(assert) {
   assert.expect(3);
 
-  const first = 'foo';
-  const second = [3, 5];
-  const third = [4, 9];
+  let first = 'foo';
+  let second = [3, 5];
+  let third = [4, 9];
 
   innerComponent = EmberComponent.extend({
     fireAction() {
@@ -384,7 +384,7 @@ QUnit.test('action can create closures over actions with target', function(asser
 QUnit.test('value can be used with action over actions', function(assert) {
   assert.expect(1);
 
-  const newValue = 'yelping yehuda';
+  let newValue = 'yelping yehuda';
 
   innerComponent = EmberComponent.extend({
     fireAction() {
@@ -419,7 +419,7 @@ QUnit.test('value can be used with action over actions', function(assert) {
 QUnit.test('action will read the value of a first property', function(assert) {
   assert.expect(1);
 
-  const newValue = 'irate igor';
+  let newValue = 'irate igor';
 
   innerComponent = EmberComponent.extend({
     fireAction() {
@@ -449,7 +449,7 @@ QUnit.test('action will read the value of a first property', function(assert) {
 QUnit.test('action will read the value of a curried first argument property', function(assert) {
   assert.expect(1);
 
-  const newValue = 'kissing kris';
+  let newValue = 'kissing kris';
 
   innerComponent = EmberComponent.extend({
     fireAction() {