chore(lint): switch from JSHint to ESLint

Fixes #2550
Switch from JSHint to ESLint
Add rules to ESLint
Also have JSHint in parallel
Remove old dependencies reported by amdcheck
Remove unused variables reported by ESLint

.eslintignore

@@ -0,0 +1,4 @@
+.tmp/**
+app/bower_components/**
+app/scripts/vendor/**
+dist/**

.eslintrc

@@ -0,0 +1,48 @@
+{
+  "env": {
+    "amd": true,
+    "es6": true,
+    "mocha": true,
+    "node": true
+  },
+  "rules": {
+    "camelcase": 0,
+    "comma-dangle": 0,
+    "complexity": [2, 6],
+    "consistent-return": 0,
+    "curly": [2, "all"],
+    "dot-notation": 0,
+    "eol-last": 2,
+    "eqeqeq": [2, "allow-null"],
+    "global-strict": [0, "never"],
+    "handle-callback-err": 0,
+    "key-spacing": 0,
+    "new-cap": 0,
+    "no-cond-assign": [2, "except-parens"],
+    "no-debugger": 2,
+    "no-empty": 0,
+    "no-eval": 2,
+    "no-irregular-whitespace": 2,
+    "no-loop-func": 0,
+    "no-multiple-empty-lines": [2, {"max": 2}],
+    "no-multi-spaces": 0,
+    "no-new": 2,
+    "no-script-url": 2,
+    "no-sequences": 2,
+    "no-shadow": 0,
+    "no-spaced-func": 0,
+    "no-trailing-spaces": 2,
+    "no-undef": 2,
+    "no-underscore-dangle": 0,
+    "no-unused-vars": [2, {"vars": "all", "args": "none"}],
+    "no-use-before-define": true,
+    "no-with": 2,
+    "quotes": [2, "single", "avoid-escape"],
+    "semi": [2, "always"],
+    "space-unary-ops": 0,
+    "strict": 2,
+    "valid-typeof": 1,
+    "wrap-iife": 0,
+    "yoda": 0
+  }
+}

.jshintrc

@@ -18,7 +18,7 @@
   "sub": true,
   "trailing": true,
   "undef": true,
-  "unused": true,
+  "unused": "vars",
   "globals": {
     "define": false,
     "Promise": true

app/.eslintrc

@@ -0,0 +1,21 @@
+{
+  "env": {
+    "browser": true,
+    "builtin": true,
+    "jquery": true,
+    "node": false
+  },
+  "rules": {
+    "globals": {
+      "router": false
+    },
+    "no-bitwise": 2,
+    "no-caller": 2,
+    "no-console": 0,
+    "no-extend-native": 2,
+    "no-multi-str": 2,
+    "no-proto": 2,
+    "strict": [2, "global"],
+    "valid-typeof": 2
+  }
+}

app/scripts/head/start.js

@@ -1,6 +1,7 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+/*globals FxaHead */
 'use strict';
 
 (function () {

app/scripts/head/startup-styles.js

@@ -9,7 +9,6 @@
 // NOTE: This file must run in IE8+, so no ES5/ES6 features!
 
 //jshint es3: true, es5: false, esnext: false
-
 'use strict';
 
 // This is loaded in the HEAD of the doc & uses a modified version of

app/scripts/lib/able.js

@@ -10,7 +10,6 @@
  * via window.able. If able is disabled in production, choose
  * will always return `undefined` and `report` will return an empty array.
  */
-
 'use strict';
 
 define([], function () {

app/scripts/lib/app-start.js

@@ -14,7 +14,6 @@
  * 5) If cookies are disabled, go to the /cookies_disabled page.
  * 6) Start the app if cookies are enabled.
  */
-
 'use strict';
 
 define([
@@ -353,7 +352,8 @@ function (
     },
 
     initializeAuthenticationBroker: function () {
-      //jshint maxcomplexity: 7
+      /*jshint maxcomplexity: 7 */
+      /*eslint complexity: [2, 7] */
       if (! this._authenticationBroker) {
         if (this._isFxDesktopV2()) {
           this._authenticationBroker = new FxDesktopV2AuthenticationBroker({

app/scripts/lib/assertion.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([

app/scripts/lib/auth-errors.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // provides functions to work with errors returned by the auth server.
-
 'use strict';
 
 define([

app/scripts/lib/base64url.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 /**

app/scripts/lib/channels/base.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 // A channel interface.

app/scripts/lib/channels/duplex.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 /**

app/scripts/lib/channels/fx-desktop.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 // Firefox for desktop native=>FxA glue code.

app/scripts/lib/channels/iframe.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 /**

app/scripts/lib/channels/inter-tab.js

@@ -6,7 +6,6 @@
  * This is a special channel that communicates between two
  * tabs of the same browser. It uses localStorage to communicate.
  */
-
 'use strict';
 
 define([

app/scripts/lib/channels/mixins/postmessage_receiver.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 /**

app/scripts/lib/channels/null.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 // A shell of a channel. Doesn't do anything yet, but is a useful standin.

app/scripts/lib/channels/receivers/web-channel.js

@@ -7,7 +7,6 @@
  * https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/WebChannel.jsm
  */
 
-
 'use strict';
 
 define([

app/scripts/lib/channels/senders/null.js

@@ -5,7 +5,6 @@
 /**
  * A null sender. Sends messages nowhere.
  */
-
 'use strict';
 
 define([

app/scripts/lib/channels/senders/web-channel.js

@@ -6,7 +6,6 @@
  * Send a message to the browser over a WebChannel. See
  * https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/WebChannel.jsm
  */
-
 'use strict';
 
 define([

app/scripts/lib/channels/web.js

@@ -5,7 +5,6 @@
 // A channel that completes the OAuth flow using Firefox WebChannel events
 // https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/WebChannel.jsm
 // https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/FxAccountsOAuthClient.jsm
-
 'use strict';
 
 define([

app/scripts/lib/config-loader.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // fetch config from the backend and provide some helper functions.
-
 'use strict';
 
 define([

app/scripts/lib/constants.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([], function () {

app/scripts/lib/cropper.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([

app/scripts/lib/environment.js

@@ -10,7 +10,6 @@
 // No ES5/ES6 features!
 
 //jshint es3: true, es5: false, esnext: false
-
 'use strict';
 
 // This is loaded in the HEAD of the doc & uses a modified version of

app/scripts/lib/ephemeral-messages.js

@@ -4,7 +4,6 @@
 
 // an ephemeral messages model. Ephemeral messages are allowed
 // a single `get` and no more.
-
 'use strict';
 
 define([

app/scripts/lib/errors.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([

app/scripts/lib/fxa-client.js

@@ -5,7 +5,6 @@
 // a very light wrapper around the real FxaClient to reduce boilerplate code
 // and to allow us to develop to features that are not yet present in the real
 // client.
-
 'use strict';
 
 define([

app/scripts/lib/marketing-email-client.js

@@ -5,7 +5,6 @@
 /**
  * A client to talk to the basket marketing email server
  */
-
 'use strict';
 
 define([

app/scripts/lib/marketing-email-errors.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // provides functions to work with errors returned by the auth server.
-
 'use strict';
 
 define([

app/scripts/lib/metrics.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-'use strict';
 
 /*
  * A metrics module!
@@ -14,6 +13,7 @@
  * Metrics are automatically sent to the server on window.unload
  * but can also be sent by calling metrics.flush();
  */
+'use strict';
 
 define([
   'underscore',
@@ -62,6 +62,7 @@ define([
 
   function Metrics (options) {
     /*jshint maxcomplexity:18 */
+    /*eslint complexity: [2, 18] */
     options = options || {};
 
     // by default, send the metrics to the content server.

app/scripts/lib/null-storage.js

@@ -4,7 +4,6 @@
 
 // This is a memory store that's api compatible with localStorage/sessionStorage.
 // It's used for testing lib/storage.
-
 'use strict';
 
 define([

app/scripts/lib/oauth-client.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([

app/scripts/lib/oauth-errors.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // provides functions to work with errors returned by the auth server.
-
 'use strict';
 
 define([

app/scripts/lib/profile-client.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // This module handles communication with the fxa-profile-server.
-
 'use strict';
 
 define([

app/scripts/lib/profile-errors.js

@@ -1,7 +1,6 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
 'use strict';
 
 define([

app/scripts/lib/relier-keys.js

@@ -5,7 +5,6 @@
 /**
  * Derive relier-specific encryption keys from account master keys.
  */
-
 'use strict';
 
 define([

app/scripts/lib/screen-info.js

@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // module to calculate screen dimentions given a window.
-
 'use strict';
 
 define([
@@ -12,6 +11,7 @@ define([
 
   function ScreenInfo(win) {
     /*jshint maxcomplexity:8 */
+    /*eslint complexity: [2, 8] */
     var documentElement = win.document.documentElement || {};
     var screen = win.screen || {};