Issue 4795 - Use modern JavaScript syntax

ext/background.js

Index: ext/background.js
diff --git a/ext/background.js b/ext/background.js
index f6ce8ce075bae22f0569a1cdd741ee29646ba580..d8f67beff947da4193fdddaa5dd1a655ae5a4446 100644
--- a/ext/background.js
+++ b/ext/background.js
@@ -15,55 +15,56 @@
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-(function()
+"use strict";
+
 {
-  var nonEmptyPageMaps = Object.create(null);
-  var pageMapCounter = 0;
+  let nonEmptyPageMaps = Object.create(null);

[Sebastian Noack, 2017/01/16 14:47:40]

In "modern JavaScript" you wouldn't (mis)use objects as hashtable, but use Map
objects instead. Not sure whether it is worth to change this, if it is only for
the to be removed abstraction layer. But there might be more occurrences of this
pattern.

[kzar, 2017/01/16 14:59:07]

Good point, but would you mind if we left that for a second review? This is
already getting fairly unwieldly.

[Sebastian Noack, 2017/01/16 15:35:54]

Acknowledged.

+  let pageMapCounter = 0;
 
-  var PageMap = ext.PageMap = function()
+  let PageMap = ext.PageMap = function()
   {
     this._map = Object.create(null);
     this._id = ++pageMapCounter;
   };
   PageMap.prototype = {
-    _delete: function(id)
+    _delete(id)
     {
       delete this._map[id];
 
       if (Object.keys(this._map).length == 0)
         delete nonEmptyPageMaps[this._id];
     },
-    keys: function()
+    keys()
     {
       return Object.keys(this._map).map(ext.getPage);
     },
-    get: function(page)
+    get(page)
     {
       return this._map[page.id];
     },
-    set: function(page, value)
+    set(page, value)
     {
       this._map[page.id] = value;
       nonEmptyPageMaps[this._id] = this;
     },
-    has: function(page)
+    has(page)
     {
       return page.id in this._map;
     },
-    clear: function()
+    clear()
     {
-      for (var id in this._map)
+      for (let id in this._map)
         this._delete(id);
     },
-    delete: function(page)
+    delete(page)
     {
       this._delete(page.id);
     }
   };
 
-  ext._removeFromAllPageMaps = function(pageId)
+  ext._removeFromAllPageMaps = pageId =>
   {
-    for (var pageMapId in nonEmptyPageMaps)
+    for (let pageMapId in nonEmptyPageMaps)
       nonEmptyPageMaps[pageMapId]._delete(pageId);
   };
-})();
+}