Issue 4783 - Use modern JavaScript syntax for the messageResponder

messageResponder.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 =>

[Sebastian Noack, 2017/01/11 16:29:08]

Do we even need an IIFE with ES6? Wouldn't a simple, unconditional block have
the same effect, as long as we use let (instead of var) inside the block?

[kzar, 2017/01/13 08:44:49]

Good point, Done.

[Sebastian Noack, 2017/01/13 11:54:48]

I just noticed, you'd also have to use strict mode, otherwise named functions
aren't block-scoped.

[kzar, 2017/01/16 04:41:49]

Done.

+"use strict";
+
 {
-  if (!global.ext)
-    global.ext = require("ext_background");
-
-  let port = require("messaging").port;
-  let Prefs = require("prefs").Prefs;
-  let Utils = require("utils").Utils;
-  let FilterStorage = require("filterStorage").FilterStorage;
-  let FilterNotifier = require("filterNotifier").FilterNotifier;
-  let defaultMatcher = require("matcher").defaultMatcher;
-  let ElemHideEmulation = require("elemHideEmulation").ElemHideEmulation;
-  let NotificationStorage = require("notification").Notification;
-
-  let filterClasses = require("filterClasses");
-  let Filter = filterClasses.Filter;
-  let BlockingFilter = filterClasses.BlockingFilter;
-  let RegExpFilter = filterClasses.RegExpFilter;
-  let Synchronizer = require("synchronizer").Synchronizer;
-
-  let info = require("info");
-  let subscriptionClasses = require("subscriptionClasses");
-  let Subscription = subscriptionClasses.Subscription;
-  let DownloadableSubscription = subscriptionClasses.DownloadableSubscription;
-  let SpecialSubscription = subscriptionClasses.SpecialSubscription;
+  var ext = ext || require("ext_background");
+
+  const {port} = require("messaging");
+  const {Prefs} = require("prefs");
+  const {Utils} = require("utils");
+  const {FilterStorage} = require("filterStorage");
+  const {FilterNotifier} = require("filterNotifier");
+  const {defaultMatcher} = require("matcher");
+  const {ElemHideEmulation} = require("elemHideEmulation");
+  const {Notification: NotificationStorage} = require("notification");
+
+  const {Filter, BlockingFilter, RegExpFilter} = require("filterClasses");
+  const {Synchronizer} = require("synchronizer");
+
+  const info = require("info");
+  const {Subscription,
+         DownloadableSubscription,
+         SpecialSubscription} = require("subscriptionClasses");
 
   // Some modules doesn't exist on Firefox. Moreover,
   // require() throws an exception on Firefox in that case.
   // However, try/catch causes the whole function to to be
   // deoptimized on V8. So we wrap it into another function.
   function tryRequire(module)
   {
     try
     {
       return require(module);
     }
     catch (e)
     {
       return null;
     }
   }
 
   function convertObject(keys, obj)
   {
     let result = {};
     for (let key of keys)
+    {
       if (key in obj)
         result[key] = obj[key];
+    }
     return result;
   }
 
   function convertSubscription(subscription)
   {
     let obj = convertObject(["disabled", "downloadStatus", "homepage",
                              "lastDownload", "title", "url"], subscription);
     obj.isDownloading = Synchronizer.isExecuting(subscription.url);
     return obj;
   }
 
   let convertFilter = convertObject.bind(null, ["text"]);
 
-  let changeListeners = new global.ext.PageMap();
+  let changeListeners = new ext.PageMap();
   let listenedPreferences = Object.create(null);
   let listenedFilterChanges = Object.create(null);
   let messageTypes = {
     "app": "app.respond",
     "filter": "filters.respond",
     "pref": "prefs.respond",
     "subscription": "subscriptions.respond"
   };
 
   function sendMessage(type, action)
@@ skipping 24 matching lines @@
           type: messageTypes[type],
           action: action,
           args: args
         });
       }
     }
   }
 
   function addFilterListeners(type, actions)
   {
-    actions.forEach(action =>
+    for (let action of actions)
     {
       let name;
       if (type == "filter" && action == "loaded")
         name = "load";
       else
         name = type + "." + action;
 
       if (!(name in listenedFilterChanges))
       {
         listenedFilterChanges[name] = null;
         FilterNotifier.on(name, function()

[kzar, 2017/01/11 08:50:44]

(I originally used an arrow function here but that broke things since they do
not bind the arguments variable!)

         {
           let args = [type, action];
           for (let arg of arguments)
             args.push(arg);
           sendMessage.apply(null, args);
         });
       }
-    });
+    }
   }
 
   function getListenerFilters(page)
   {
     let listenerFilters = changeListeners.get(page);
     if (!listenerFilters)
     {
       listenerFilters = Object.create(null);
       changeListeners.set(page, listenerFilters);
     }
@@ skipping 71 matching lines @@
       message.thirdParty);
 
     return filter instanceof BlockingFilter;
   });
 
   port.on("filters.get", (message, sender) =>
   {
     if (message.what == "elemhideemulation")
     {
       let filters = [];
-      let checkWhitelisted = require("whitelisting").checkWhitelisted;
+      const {checkWhitelisted} = require("whitelisting");
 
       if (Prefs.enabled && !checkWhitelisted(sender.page, sender.frame,
                             RegExpFilter.typeMap.DOCUMENT |
                             RegExpFilter.typeMap.ELEMHIDE))
       {
         let hostname = sender.frame.url.hostname;
         filters = ElemHideEmulation.getRulesForDomain(hostname);
         filters = filters.map(filter =>
         {
           return {
@@ skipping 10 matching lines @@
       return [];
 
     return subscription.filters.map(convertFilter);
   });
 
   port.on("filters.importRaw", (message, sender) =>
   {
     let result = require("filterValidation").parseFilters(message.text);
     let errors = [];
     for (let error of result.errors)
+    {
       if (error.type != "unexpected-filter-list-header")
         errors.push(error.toString());
+    }
 
     if (errors.length > 0)
       return errors;
 
     let seenFilter = Object.create(null);
     for (let filter of result.filters)
     {
       FilterStorage.addFilter(filter);
       seenFilter[filter.text] = null;
     }
@@ skipping 40 matching lines @@
   });
 
   port.on("prefs.get", (message, sender) =>
   {
     return Prefs[message.key];
   });
 
   port.on("prefs.listen", (message, sender) =>
   {
     getListenerFilters(sender.page).pref = message.filter;
-    message.filter.forEach(preference =>
+    for (let preference of message.filter)
     {
       if (!(preference in listenedPreferences))
       {
         listenedPreferences[preference] = null;
         Prefs.on(preference, () =>
         {
           sendMessage("pref", preference, Prefs[preference]);
         });
       }
-    });
+    }
   });
 
   port.on("prefs.toggle", (message, sender) =>
   {
     if (message.key == "notifications_ignoredcategories")
       NotificationStorage.toggleIgnoreCategory("*");
     else
       Prefs[message.key] = !Prefs[message.key];
   });
 
@@ skipping 70 matching lines @@
       if (!subscription.lastDownload)
         Synchronizer.execute(subscription);
     }
   });
 
   port.on("subscriptions.update", (message, sender) =>
   {
     let subscriptions = message.url ? [Subscription.fromURL(message.url)] :
                         FilterStorage.subscriptions;
     for (let subscription of subscriptions)
+    {
       if (subscription instanceof DownloadableSubscription)
         Synchronizer.execute(subscription, true);
-  });
-})(this);
+    }
+  });
+}