Issue 4864 - Start using ESLint for adblockpluschrome

include.preload.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 ElemHideEmulation, splitSelector */
 
 "use strict";
 
+// This variable is also used by our other content scripts.
+let elemhide;
+
 const typeMap = new Map([
   ["img", "IMAGE"],
   ["input", "IMAGE"],
   ["picture", "IMAGE"],
   ["audio", "MEDIA"],
   ["video", "MEDIA"],
   ["frame", "SUBDOCUMENT"],
   ["iframe", "SUBDOCUMENT"],
   ["object", "OBJECT"],
   ["embed", "OBJECT"]
@@ skipping 142 matching lines @@
   );
 }
 
 function checkSitekey()
 {
   let attr = document.documentElement.getAttribute("data-adblockkey");
   if (attr)
     ext.backgroundPage.sendMessage({type: "filters.addKey", token: attr});
 }
 
-function getContentDocument(element)
-{
-  try
-  {
-    return element.contentDocument;
-  }
-  catch (e)
-  {
-    return null;
-  }
-}
-
-function ElementHidingTracer(selectors)
-{
-  this.selectors = selectors;
+function ElementHidingTracer()
+{
+  this.selectors = [];
+  this.filters = [];
 
   this.changedNodes = [];
   this.timeout = null;
 
   this.observer = new MutationObserver(this.observe.bind(this));
   this.trace = this.trace.bind(this);
 
   if (document.readyState == "loading")
     document.addEventListener("DOMContentLoaded", this.trace);
   else
     this.trace();
 }
 ElementHidingTracer.prototype = {
-  checkNodes(nodes)
+  addSelectors(selectors, filters)
+  {
+    if (document.readyState != "loading")
+      this.checkNodes([document], selectors, filters);
+
+    this.selectors.push(...selectors);
+    this.filters.push(...filters);
+  },
+
+  checkNodes(nodes, selectors, filters)
   {
     let matchedSelectors = [];
 
-    // Find all selectors that match any hidden element inside the given nodes.
-    for (let selector of this.selectors)
-    {
-      for (let node of nodes)
-      {
-        let elements = node.querySelectorAll(selector);
-        let matched = false;
+    for (let i = 0; i < selectors.length; i++)
+    {
+      nodes: for (let node of nodes)
+      {
+        let elements = node.querySelectorAll(selectors[i]);
 
         for (let element of elements)
         {
           // Only consider selectors that actually have an effect on the
           // computed styles, and aren't overridden by rules with higher
           // priority, or haven't been circumvented in a different way.
           if (getComputedStyle(element).display == "none")
           {
-            matchedSelectors.push(selector);
-            matched = true;
-            break;
+            matchedSelectors.push(filters[i].replace(/^.*?##/, ""));
+            break nodes;
           }
         }
-
-        if (matched)
-          break;
       }
     }
 
     if (matchedSelectors.length > 0)
     {
       ext.backgroundPage.sendMessage({
         type: "devtools.traceElemHide",
         selectors: matchedSelectors
       });
     }
   },
 
   onTimeout()
   {
-    this.checkNodes(this.changedNodes);
+    this.checkNodes(this.changedNodes, this.selectors, this.filters);
     this.changedNodes = [];
     this.timeout = null;
   },
 
   observe(mutations)
   {
     // Forget previously changed nodes that are no longer in the DOM.
     for (let i = 0; i < this.changedNodes.length; i++)
     {
       if (!document.contains(this.changedNodes[i]))
@@ skipping 41 matching lines @@
 
     // Check only nodes whose descendants have changed, and not more often
     // than once a second. Otherwise large pages with a lot of DOM mutations
     // (like YouTube) freeze when the devtools panel is active.
     if (this.timeout == null)
       this.timeout = setTimeout(this.onTimeout.bind(this), 1000);
   },
 
   trace()
   {
-    this.checkNodes([document]);
+    this.checkNodes([document], this.selectors, this.filters);
 
     this.observer.observe(
       document,
       {
         childList: true,
         attributes: true,
         subtree: true
       }
     );
   },
 
   disconnect()
   {
     document.removeEventListener("DOMContentLoaded", this.trace);
     this.observer.disconnect();
     clearTimeout(this.timeout);
   }
 };
 
 function runInPageContext(fn, arg)
 {
   let script = document.createElement("script");
   script.type = "application/javascript";
   script.async = false;
   script.textContent = "(" + fn + ")(" + JSON.stringify(arg) + ");";
   document.documentElement.appendChild(script);
   document.documentElement.removeChild(script);
 }
 
-// Chrome doesn't allow us to intercept WebSockets[1], and therefore
-// some ad networks are misusing them as a way to serve adverts and circumvent
-// us. As a workaround we wrap WebSocket, preventing blocked WebSocket
-// connections from being opened.
+// Before Chrome 58 the webRequest API didn't allow us to intercept
+// WebSockets[1], and therefore some ad networks are misusing them as a way to
+// serve adverts and circumvent us. As a workaround we wrap WebSocket,
+// preventing blocked WebSocket connections from being opened.
 // [1] - https://bugs.chromium.org/p/chromium/issues/detail?id=129353
 function wrapWebSocket()
 {
   let randomEventName = "abpws-" + Math.random().toString(36).substr(2);
 
   document.addEventListener(randomEventName, event =>
   {
     ext.backgroundPage.sendMessage({
       type: "request.websocket",
       url: event.detail.url
@@ skipping 30 matching lines @@
 
       dispatchEvent(new RealCustomEvent(eventName, {detail: {url}}));
     }
 
     function WrappedWebSocket(url, ...args)
     {
       // Throw correct exceptions if the constructor is used improperly.
       if (!(this instanceof WrappedWebSocket)) return RealWebSocket();
       if (arguments.length < 1) return new RealWebSocket();
 
-      let websocket;
-      if (arguments.length == 1)
-        websocket = new RealWebSocket(url);
-      else
-        websocket = new RealWebSocket(url, args[0]);
+      let websocket = new RealWebSocket(url, ...args);
 
       checkRequest(websocket.url, blocked =>
       {
         if (blocked)
           closeWebSocket(websocket);
       });
 
       return websocket;
     }
     WrappedWebSocket.prototype = RealWebSocket.prototype;
@@ skipping 61 matching lines @@
         if (!ourShadowRoot)
           return;
         let desc = Object.getOwnPropertyDescriptor(Element.prototype,
                                                    "shadowRoot");
         let shadowRoot = Function.prototype.call.bind(desc.get);
 
         Object.defineProperty(Element.prototype, "shadowRoot", {
           configurable: true, enumerable: true, get()
           {
             let thisShadow = shadowRoot(this);
-            return thisShadow == ourShadowRoot ? null : shadow;
+            return thisShadow == ourShadowRoot ? null : thisShadow;
           }
         });
       }, null);
     }
 
     return shadow;
   },
 
-  addSelectors(selectors)
+  addSelectors(selectors, filters)
   {
     if (selectors.length == 0)
       return;
 
     if (!this.style)
     {
       // Create <style> element lazily, only if we add styles. Add it to
       // the shadow DOM if possible. Otherwise fallback to the <head> or
       // <html> element. If we have injected a style element before that
       // has been removed (the sheet property is null), create a new one.
       this.style = document.createElement("style");
       (this.shadow || document.head ||
-       document.documentElement).appendChild(this.style);
+                      document.documentElement).appendChild(this.style);
 
       // It can happen that the frame already navigated to a different
       // document while we were waiting for the background page to respond.
       // In that case the sheet property will stay null, after addind the
       // <style> element to the shadow DOM.
       if (!this.style.sheet)
         return;
     }
 
     // If using shadow DOM, we have to add the ::content pseudo-element
     // before each selector, in order to match elements within the
     // insertion point.
+    let preparedSelectors = [];
     if (this.shadow)
     {
-      let preparedSelectors = [];
       for (let selector of selectors)
       {
         let subSelectors = splitSelector(selector);
         for (let subSelector of subSelectors)
           preparedSelectors.push("::content " + subSelector);
       }
-      selectors = preparedSelectors;
+    }
+    else
+    {
+      preparedSelectors = selectors;
     }
 
     // Safari only allows 8192 primitive selectors to be injected at once[1], we
     // therefore chunk the inserted selectors into groups of 200 to be safe.
     // (Chrome also has a limit, larger... but we're not certain exactly what it
     //  is! Edge apparently has no such limit.)
     // [1] - https://github.com/WebKit/webkit/blob/1cb2227f6b2a1035f7bdc46e5ab69debb75fc1de/Source/WebCore/css/RuleSet.h#L68
-    for (let i = 0; i < selectors.length; i += this.selectorGroupSize)
-    {
-      let selector = selectors.slice(i, i + this.selectorGroupSize).join(", ");
+    for (let i = 0; i < preparedSelectors.length; i += this.selectorGroupSize)
+    {
+      let selector = preparedSelectors.slice(
+        i, i + this.selectorGroupSize
+      ).join(", ");
       this.style.sheet.insertRule(selector + "{display: none !important;}",
                                   this.style.sheet.cssRules.length);
     }
+
+    if (this.tracer)
+      this.tracer.addSelectors(selectors, filters || selectors);
   },
 
   apply()
   {
-    let selectors = null;
-    let elemHideEmulationLoaded = false;
-
-    let checkLoaded = function()
-    {
-      if (!selectors || !elemHideEmulationLoaded)
-        return;
-
+    ext.backgroundPage.sendMessage({type: "get-selectors"}, response =>
+    {
       if (this.tracer)
         this.tracer.disconnect();
       this.tracer = null;
 
       if (this.style && this.style.parentElement)
         this.style.parentElement.removeChild(this.style);
       this.style = null;
 
-      this.addSelectors(selectors.selectors);
+      if (response.trace)
+        this.tracer = new ElementHidingTracer();
+
+      this.addSelectors(response.selectors);
       this.elemHideEmulation.apply();
-
-      if (selectors.trace)
-        this.tracer = new ElementHidingTracer(selectors.selectors);
-    }.bind(this);
-
-    ext.backgroundPage.sendMessage({type: "get-selectors"}, response =>
-    {
-      selectors = response;
-      checkLoaded();
-    });
-
-    this.elemHideEmulation.load(() =>
-    {
-      elemHideEmulationLoaded = true;
-      checkLoaded();
     });
   }
 };
 
 if (document instanceof HTMLDocument)
 {
   checkSitekey();
   wrapWebSocket();
 
-  // This variable is also used by our other content scripts, outside of the
-  // current scope.
-  /* eslint-disable no-var */
-  var elemhide = new ElemHide();
-  /* eslint-enable no-var */
+  elemhide = new ElemHide();
   elemhide.apply();
 
   document.addEventListener("error", event =>
   {
     checkCollapse(event.target);
   }, true);
 
   document.addEventListener("load", event =>
   {
     let element = event.target;
     if (/^i?frame$/.test(element.localName))
       checkCollapse(element);
   }, true);
 }