Rewrite References api in ES9 (#813)

* rewrite references api with es9 and Promises
- es9 .eslintrc which extends the default .eslintrc
- start rewriting tests/server/reference-create.server.routes.tests.js
- fix eslint var/let/const errors in remaining reference server tests

* further es7ifying of reference-create.server.routes.tests

* organize .eslintrc files, keep moving reference tests to es7+

* tests/server/reference-read-one.server.routes.tests to es7+

* reference.server.jobs.tests to es7+
- small fix in reference-read-many tests

* reference.server.model.tests to es7+

* migrate modules/references/server to es7+

* use .eslintrc.js with overrides for es9 configuration

* make eslint rules for es2018 more consistent and strict
- fix eslint rules and add exceptions to eslint rules

.eslintrc.js

@@ -1,8 +1,14 @@
+const es2018rules = {
+  'no-var': 2,
+  'prefer-const': 2,
+  'arrow-spacing': [2, { before: true, after: true }]
+};
+
 module.exports = {
-  parserOptions: {
-    ecmaVersion: 2018,
-    sourceType: 'module'
-  },
+  /*
+   * this would ideally belong to the react overrides, but overrides can't include extends
+   * https://github.com/eslint/eslint/issues/8813
+   */
   extends: [
     'plugin:react/recommended'
   ],
@@ -86,5 +92,38 @@ module.exports = {
     __TESTING__: true,
     _: false,
     AppConfig: true
-  }
+  },
+  /*
+    eventually, after the migration, these overrides will become the main rules
+
+    it would be nice to keep the rules for client and server separate,
+    because eventually, they want to become independent codebases.
+  */
+  overrides: [{
+    // overrides for server code
+    // ES 2018 - specify migrated files and folders here
+    files: [
+      'testutils/data.server.testutils.js',
+      'modules/references/server/**',
+      'modules/references/tests/server/**'
+    ],
+    parserOptions: {
+      ecmaVersion: 2018
+    },
+    rules: es2018rules
+  }, {
+    // overrides for client/react code
+    files: [
+      'config/webpack/**',
+      'modules/core/client/app/config.js',
+      'modules/**/client/components/**',
+      'modules/core/client/directives/tr-boards.client.directive.js',
+      'modules/core/client/services/photos.service.js'
+    ],
+    parserOptions: {
+      ecmaVersion: 2018,
+      sourceType: 'module'
+    },
+    rules: es2018rules
+  }]
 };

config/webpack/entries/pushMessagingServiceWorker.js

@@ -7,7 +7,7 @@ firebase.initializeApp({
   'messagingSenderId': FCM_SENDER_ID
 });
 
-var messaging = firebase.messaging();
+const messaging = firebase.messaging();
 
 messaging.setBackgroundMessageHandler(function (payload) {
   // not actually used, but without it here firefox does not receive messages...

modules/core/client/app/config.js

@@ -1,4 +1,5 @@
 'use strict';
+/* eslint no-var: 0 */
 
 import ngreact from 'ngreact';
 

modules/core/client/directives/tr-boards.client.directive.js

@@ -1,3 +1,4 @@
+/* eslint no-var: 0 */
 import photos from '@/modules/core/client/services/photos.service';
 
 (function () {