Issue 4864 - Start using ESLint for adblockpluschrome

lib/io.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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/>.
  */
 
+/* global FakeFile */

[Sebastian Noack, 2017/02/09 01:04:51]

Is FakeFile used anywhere else? Can't we just turn lib/compat.js into a module?
Same for "Services" which I've seen to be used as global somewhere else.

As far as adblockpluscore is concerned, with the current Adblock Plus for
Firefox on the way out, having this compatibility layer seems wrong to have in
the first place. But for the time being I wouldn't mind to keep it, but at least
we should turn it into a module, to avoid globals in adblockpluschrome, and
assign to window where necessary for compatibility with adblockpluscore.

[kzar, 2017/02/20 10:27:33]

Not that I can see, no.
Well how would that work since lib/compat.js is where we define `require`. Do
you suggest we split the module framework stuff away from the rest of
lib/compat.js and then turn what's left into a module?
IMO it's better to use a global variable and explicitly document it's use with a
ESLint comment than it is to shove the same variable inside the global `window`
Object in order to pretend it doesn't exist. At least then the global state is
documented. (FWIW I agree to reduce global state is almost always a good thing.)

+
 "use strict";
 
 const keyPrefix = "file:";
 
 function fileToKey(file)
 {
   return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
 }
 
 function loadFile(file, successCallback, errorCallback)
@@ skipping 80 matching lines @@
     {
       callback(null, {
         exists: true,
         lastModified: entry.lastModified
       });
     }
 
     loadFile(file, onLoaded, callback);
   }
 };