Issue 4864 - Start using ESLint for adblockpluschrome

composer.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2016 Eyeo GmbH
+ * Copyright (C) 2006-2017 eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-/* globals $ */

[Sebastian Noack, 2017/02/09 01:04:50]

I guess we should rather enable the "jquery" environment, than whitelisting "$"
explicitly, if it is just to avoid confusion with Chrome's built-in "$".

Also I'm not too happy with the inline configurations spread across our code. I
wonder whether it would be worth to add the "jQuery" environment to the global
configuration. On the other hand, it's not available in all files. But then
again, this is also true for some of the other environments configured globally,
and this isn't the only file using jQuery either.

[kzar, 2017/02/20 10:27:30]

IMO explicitly adding global comments at the top of relevant files like this
isn't too big a deal, and as Wladimir pointed out they are actually useful as
they act as documentation of the global variables in the code for humans too.

That said I don't have a strong opinion about if `/* globals $ */` or `/*
eslint-env jquery */` looks nicer here, so up to you I guess.

I think adding the jQuery environment globally to the configuration would be a
footgun since like you say those variables aren't available throughout. So the
fact the configuration implied they were would be misleading and also we would
lose some of the benefit of using the no-undef rule in the process.

+/* eslint-env jquery */
 
 "use strict";
 
 let targetPageId = null;
 
 function onKeyDown(event)
 {
   if (event.keyCode == 27)
   {
     event.preventDefault();
@@ skipping 60 matching lines @@
         break;
       case "composer.dialog.close":
         window.close();
         break;
     }
   });
 
   window.removeEventListener("load", init);
 }
 window.addEventListener("load", init, false);