Issue 4795 - Use modern JavaScript syntax

lib/utils.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/>.
  */
 
-var Utils = exports.Utils = {
+"use strict";
+
+let Utils = exports.Utils = {
   systemPrincipal: null,
-  getString: function(id)
-  {
-    return ext.i18n.getMessage("global_" + id);
-  },
-  runAsync: function(callback)
+  getString: id => ext.i18n.getMessage("global_" + id),
+  runAsync: callback =>
   {
     if (document.readyState == "loading")
     {
       // Make sure to not run asynchronous actions before all
       // scripts loaded. This caused issues on Opera in the past.
-      let onDOMContentLoaded = function()
+      let onDOMContentLoaded = () =>
       {
         document.removeEventListener("DOMContentLoaded", onDOMContentLoaded);
         callback();
       };
       document.addEventListener("DOMContentLoaded", onDOMContentLoaded);
     }
     else
     {
       setTimeout(callback, 0);
     }
   },
   get appLocale()
   {
-    var locale = ext.i18n.getMessage("@@ui_locale").replace(/_/g, "-");
+    let locale = ext.i18n.getMessage("@@ui_locale").replace(/_/g, "-");
     Object.defineProperty(this, "appLocale", {value: locale, enumerable: true});
     return this.appLocale;
   },
-  generateChecksum: function(lines)
-  {
-    // We cannot calculate MD5 checksums yet :-(
-    return null;
-  },
+  // We cannot calculate MD5 checksums yet :-(
+  generateChecksum: lines => null,
   checkLocalePrefixMatch: function(prefixes)
   {
     if (!prefixes)
       return null;
 
-    var list = prefixes.split(",");
-    for (var i = 0; i < list.length; i++)
-      if (new RegExp("^" + list[i] + "\\b").test(this.appLocale))
-        return list[i];
+    for (let prefix of prefixes.split(","))
+      if (new RegExp("^" + prefix + "\\b").test(this.appLocale))
+        return prefix;
 
     return null;
   },
 
-  chooseFilterSubscription: function(subscriptions)
+  chooseFilterSubscription: subscriptions =>
   {
-    var selectedItem = null;
-    var selectedPrefix = null;
-    var matchCount = 0;
-    for (var i = 0; i < subscriptions.length; i++)
+    let selectedItem = null;
+    let selectedPrefix = null;
+    let matchCount = 0;
+    for (let subscription of subscriptions)
     {
-      var subscription = subscriptions[i];
       if (!selectedItem)
         selectedItem = subscription;
 
-      var prefix = require("utils").Utils.checkLocalePrefixMatch(subscription.getAttribute("prefixes"));
+      let prefix = require("utils").Utils.checkLocalePrefixMatch(subscription.getAttribute("prefixes"));
       if (prefix)
       {
         if (!selectedPrefix || selectedPrefix.length < prefix.length)
         {
           selectedItem = subscription;
           selectedPrefix = prefix;
           matchCount = 1;
         }
         else if (selectedPrefix && selectedPrefix.length == prefix.length)
         {
           matchCount++;
 
           // If multiple items have a matching prefix of the same length:
           // Select one of the items randomly, probability should be the same
           // for all items. So we replace the previous match here with
           // probability 1/N (N being the number of matches).
           if (Math.random() * matchCount < 1)
           {
             selectedItem = subscription;
             selectedPrefix = prefix;
           }
         }
       }
     }
     return selectedItem;
   },
 
-  getDocLink: function(linkID)
+  getDocLink: linkID =>
   {
-    var Prefs = require("prefs").Prefs;
-    var docLink = Prefs.documentation_link;
+    let Prefs = require("prefs").Prefs;
+    let docLink = Prefs.documentation_link;
     return docLink.replace(/%LINK%/g, linkID).replace(/%LANG%/g, Utils.appLocale);
   },
 
-  yield: function()
+  yield: () =>
   {
   }
 };