Bug 1484413: Split ReaderMode.jsm into separate checking and loading components. r=Gijs
authorKris Maglione <maglione.k@gmail.com>
Fri, 17 Aug 2018 23:10:59 -0700
changeset 435301 9735b9bf7b466660a2422bd7689968f114847fc3
parent 435300 55690779a96d595364cce373f2abf9ff3e536037
child 435302 da268c77ac7630925921792ffc32111ae3faf7a9
child 435305 123d63eccdb7a0687bf68a9e14eda7b32c967d89
push id34602
push userdvarga@mozilla.com
push dateSat, 08 Sep 2018 03:54:14 +0000
treeherdermozilla-central@da268c77ac76 [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
reviewersGijs
bugs1484413
milestone64.0a1
first release with
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
last release without
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
Bug 1484413: Split ReaderMode.jsm into separate checking and loading components. r=Gijs Most of the ReaderMode.jsm and Readability.js code is only needed when we actually need to render a document in reader mode, but also winds up loaded into any process where we ever check if a page is readerable. This winds up wasting a huge amount of memory (and probably a huge amount of CPU time) loading code which is almost never used. This patch splits ReaderMode.jsm into two modules, one for checking readability, one for actually entering reader mode. It also separates out the isProbablyReaderable checks from Readability.js, since the overhead of loading that script before it's needed is unsupportable. This means we're probably going to need some effort to keep Readerable.jsm and Readability.js in sync, but the code in question is pretty trivial, so it shouldn't be too difficult. Differential Revision: https://phabricator.services.mozilla.com/D3687
.eslintignore
browser/actors/AboutReaderChild.jsm
browser/base/content/test/performance/browser_startup_content.js
mobile/android/chrome/content/content.js
toolkit/components/reader/Readability-readerable.js
toolkit/components/reader/Readability.js
toolkit/components/reader/ReaderMode.jsm
toolkit/components/reader/Readerable.js
toolkit/components/reader/Readerable.jsm
toolkit/components/reader/moz.build
--- a/.eslintignore
+++ b/.eslintignore
@@ -365,15 +365,16 @@ toolkit/modules/tests/xpcshell/test_task
 # External code:
 browser/components/payments/res/vendor/*
 toolkit/components/microformats/test/**
 toolkit/components/microformats/microformat-shiv.js
 toolkit/components/reader/Readability.js
 toolkit/components/reader/JSDOMParser.js
 
 # Uses preprocessing
+toolkit/components/reader/Readerable.jsm
 toolkit/content/widgets/wizard.xml
 toolkit/modules/AppConstants.jsm
 toolkit/mozapps/update/tests/data/xpcshellConstantsPP.js
 
 # Third party
 toolkit/modules/third_party/**
 third_party/**
--- a/browser/actors/AboutReaderChild.jsm
+++ b/browser/actors/AboutReaderChild.jsm
@@ -7,16 +7,18 @@
 var EXPORTED_SYMBOLS = ["AboutReaderChild"];
 
 ChromeUtils.import("resource://gre/modules/ActorChild.jsm");
 
 ChromeUtils.defineModuleGetter(this, "AboutReader",
                                "resource://gre/modules/AboutReader.jsm");
 ChromeUtils.defineModuleGetter(this, "ReaderMode",
                                "resource://gre/modules/ReaderMode.jsm");
+ChromeUtils.defineModuleGetter(this, "Readerable",
+                               "resource://gre/modules/Readerable.jsm");
 
 class AboutReaderChild extends ActorChild {
   constructor(mm) {
     super(mm);
 
     this._articlePromise = null;
     this._isLeavingReaderableReaderMode = false;
   }
@@ -97,17 +99,17 @@ class AboutReaderChild extends ActorChil
 
   /**
    * NB: this function will update the state of the reader button asynchronously
    * after the next mozAfterPaint call (assuming reader mode is enabled and
    * this is a suitable document). Calling it on things which won't be
    * painted is not going to work.
    */
   updateReaderButton(forceNonArticle) {
-    if (!ReaderMode.isEnabledForParseOnLoad || this.isAboutReader ||
+    if (!Readerable.isEnabledForParseOnLoad || this.isAboutReader ||
         !this.content || !(this.content.document instanceof this.content.HTMLDocument) ||
         this.content.document.mozSyntheticDocument) {
       return;
     }
 
     this.scheduleReadabilityCheckPostPaint(forceNonArticle);
   }
 
@@ -136,15 +138,15 @@ class AboutReaderChild extends ActorChil
     // are any painted rects.
     if (!event.clientRects.length) {
       return;
     }
 
     this.cancelPotentialPendingReadabilityCheck();
     // Only send updates when there are articles; there's no point updating with
     // |false| all the time.
-    if (ReaderMode.isProbablyReaderable(this.content.document)) {
+    if (Readerable.isProbablyReaderable(this.content.document)) {
       this.mm.sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: true });
     } else if (forceNonArticle) {
       this.mm.sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: false });
     }
   }
 }
--- a/browser/base/content/test/performance/browser_startup_content.js
+++ b/browser/base/content/test/performance/browser_startup_content.js
@@ -51,17 +51,17 @@ const whitelist = {
     "resource:///actors/AboutReaderChild.jsm",
     "resource:///actors/BrowserTabChild.jsm",
     "resource:///modules/ContentMetaHandler.jsm",
     "resource:///actors/LinkHandlerChild.jsm",
     "resource:///actors/PageStyleChild.jsm",
     "resource://gre/modules/ActorChild.jsm",
     "resource://gre/modules/ActorManagerChild.jsm",
     "resource://gre/modules/E10SUtils.jsm",
-    "resource://gre/modules/ReaderMode.jsm",
+    "resource://gre/modules/Readerable.jsm",
     "resource://gre/modules/WebProgressChild.jsm",
 
     // Pocket
     "chrome://pocket/content/AboutPocket.jsm",
 
     // Telemetry
     "resource://gre/modules/TelemetryController.jsm", // bug 1470339
     "resource://gre/modules/TelemetrySession.jsm", // bug 1470339
--- a/mobile/android/chrome/content/content.js
+++ b/mobile/android/chrome/content/content.js
@@ -3,16 +3,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
 ChromeUtils.defineModuleGetter(this, "AboutReader", "resource://gre/modules/AboutReader.jsm");
 ChromeUtils.defineModuleGetter(this, "ReaderMode", "resource://gre/modules/ReaderMode.jsm");
+ChromeUtils.defineModuleGetter(this, "Readerable", "resource://gre/modules/Readerable.jsm");
 ChromeUtils.defineModuleGetter(this, "LoginManagerContent", "resource://gre/modules/LoginManagerContent.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "gPipNSSBundle", function() {
   return Services.strings.createBundle("chrome://pipnss/locale/pipnss.properties");
 });
 XPCOMUtils.defineLazyGetter(this, "gNSSErrorsBundle", function() {
   return Services.strings.createBundle("chrome://pipnss/locale/nsserrors.properties");
 });
@@ -481,17 +482,17 @@ var AboutReaderListener = {
         this.updateReaderButton();
         break;
     }
   },
   updateReaderButton: function(forceNonArticle) {
     // Do not show Reader View icon on error pages (bug 1320900)
     if (this.isErrorPage) {
         sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: false });
-    } else if (!ReaderMode.isEnabledForParseOnLoad || this.isAboutReader ||
+    } else if (!Readerable.isEnabledForParseOnLoad || this.isAboutReader ||
         !(content.document instanceof content.HTMLDocument) ||
         content.document.mozSyntheticDocument) {
 
     } else {
         this.scheduleReadabilityCheckPostPaint(forceNonArticle);
     }
   },
 
@@ -517,21 +518,22 @@ var AboutReaderListener = {
     // possible that this page hasn't been laid out yet, in which case we
     // should wait until we get an event that does relate to our layout. We
     // determine whether any of our content got painted by checking if there
     // are any painted rects.
     if (!event.clientRects.length) {
       return;
     }
 
+    Services.console.logStringMessage(`ON PAINT WHEN WAITED FOR\n`);
     this.cancelPotentialPendingReadabilityCheck();
 
     // Only send updates when there are articles; there's no point updating with
     // |false| all the time.
-    if (ReaderMode.isProbablyReaderable(content.document)) {
+    if (Readerable.isProbablyReaderable(content.document)) {
       sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: true });
     } else if (forceNonArticle) {
       sendAsyncMessage("Reader:UpdateReaderButton", { isArticle: false });
     }
   },
 };
 AboutReaderListener.init();
 
copy from toolkit/components/reader/Readability.js
copy to toolkit/components/reader/Readability-readerable.js
--- a/toolkit/components/reader/Readability.js
+++ b/toolkit/components/reader/Readability-readerable.js
@@ -1,16 +1,10 @@
-/*eslint-env es6:false*/
-/*
- * DO NOT MODIFY THIS FILE DIRECTLY!
- *
- * This is a shared library that is maintained in an external repo:
- * https://github.com/mozilla/readability
- */
-
+/* eslint-env es6:false */
+/* globals exports */
 /*
  * Copyright (c) 2010 Arc90 Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
@@ -22,1814 +16,81 @@
  * limitations under the License.
  */
 
 /*
  * This code is heavily based on Arc90's readability.js (1.7.1) script
  * available at: http://code.google.com/p/arc90labs-readability
  */
 
-/**
- * Public constructor.
- * @param {HTMLDocument} doc     The document to parse.
- * @param {Object}       options The options object.
- */
-function Readability(doc, options) {
-  // In some older versions, people passed a URI as the first argument. Cope:
-  if (options && options.documentElement) {
-    doc = options;
-    options = arguments[2];
-  } else if (!doc || !doc.documentElement) {
-    throw new Error("First argument to Readability constructor should be a document object.");
-  }
-  options = options || {};
-
-  this._doc = doc;
-  this._articleTitle = null;
-  this._articleByline = null;
-  this._articleDir = null;
-  this._attempts = [];
-
-  // Configurable options
-  this._debug = !!options.debug;
-  this._maxElemsToParse = options.maxElemsToParse || this.DEFAULT_MAX_ELEMS_TO_PARSE;
-  this._nbTopCandidates = options.nbTopCandidates || this.DEFAULT_N_TOP_CANDIDATES;
-  this._charThreshold = options.charThreshold || this.DEFAULT_CHAR_THRESHOLD;
-  this._classesToPreserve = this.CLASSES_TO_PRESERVE.concat(options.classesToPreserve || []);
+var REGEXPS = {
+  // NOTE: These two regular expressions are duplicated in
+  // Readability.js. Please keep both copies in sync.
+  unlikelyCandidates: /-ad-|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|foot|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
+  okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
+};
 
-  // Start with all flags set
-  this._flags = this.FLAG_STRIP_UNLIKELYS |
-                this.FLAG_WEIGHT_CLASSES |
-                this.FLAG_CLEAN_CONDITIONALLY;
-
-  var logEl;
-
-  // Control whether log messages are sent to the console
-  if (this._debug) {
-    logEl = function(e) {
-      var rv = e.nodeName + " ";
-      if (e.nodeType == e.TEXT_NODE) {
-        return rv + '("' + e.textContent + '")';
-      }
-      var classDesc = e.className && ("." + e.className.replace(/ /g, "."));
-      var elDesc = "";
-      if (e.id)
-        elDesc = "(#" + e.id + classDesc + ")";
-      else if (classDesc)
-        elDesc = "(" + classDesc + ")";
-      return rv + elDesc;
-    };
-    this.log = function () {
-      if (typeof dump !== "undefined") {
-        var msg = Array.prototype.map.call(arguments, function(x) {
-          return (x && x.nodeName) ? logEl(x) : x;
-        }).join(" ");
-        dump("Reader: (Readability) " + msg + "\n");
-      } else if (typeof console !== "undefined") {
-        var args = ["Reader: (Readability) "].concat(arguments);
-        console.log.apply(console, args);
-      }
-    };
-  } else {
-    this.log = function () {};
-  }
+function isNodeVisible(node) {
+  return node.style.display != "none" && !node.hasAttribute("hidden");
 }
 
-Readability.prototype = {
-  FLAG_STRIP_UNLIKELYS: 0x1,
-  FLAG_WEIGHT_CLASSES: 0x2,
-  FLAG_CLEAN_CONDITIONALLY: 0x4,
-
-  // https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType
-  ELEMENT_NODE: 1,
-  TEXT_NODE: 3,
-
-  // Max number of nodes supported by this parser. Default: 0 (no limit)
-  DEFAULT_MAX_ELEMS_TO_PARSE: 0,
-
-  // The number of top candidates to consider when analysing how
-  // tight the competition is among candidates.
-  DEFAULT_N_TOP_CANDIDATES: 5,
-
-  // Element tags to score by default.
-  DEFAULT_TAGS_TO_SCORE: "section,h2,h3,h4,h5,h6,p,td,pre".toUpperCase().split(","),
-
-  // The default number of chars an article must have in order to return a result
-  DEFAULT_CHAR_THRESHOLD: 500,
-
-  // All of the regular expressions in use within readability.
-  // Defined up here so we don't instantiate them repeatedly in loops.
-  REGEXPS: {
-    unlikelyCandidates: /-ad-|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|foot|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
-    okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
-    positive: /article|body|content|entry|hentry|h-entry|main|page|pagination|post|text|blog|story/i,
-    negative: /hidden|^hid$| hid$| hid |^hid |banner|combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|share|shoutbox|sidebar|skyscraper|sponsor|shopping|tags|tool|widget/i,
-    extraneous: /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,
-    byline: /byline|author|dateline|writtenby|p-author/i,
-    replaceFonts: /<(\/?)font[^>]*>/gi,
-    normalize: /\s{2,}/g,
-    videos: /\/\/(www\.)?((dailymotion|youtube|youtube-nocookie|player\.vimeo|v\.qq)\.com|(archive|upload\.wikimedia)\.org|player\.twitch\.tv)/i,
-    nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
-    prevLink: /(prev|earl|old|new|<|«)/i,
-    whitespace: /^\s*$/,
-    hasContent: /\S$/,
-  },
-
-  DIV_TO_P_ELEMS: [ "A", "BLOCKQUOTE", "DL", "DIV", "IMG", "OL", "P", "PRE", "TABLE", "UL", "SELECT" ],
-
-  ALTER_TO_DIV_EXCEPTIONS: ["DIV", "ARTICLE", "SECTION", "P"],
-
-  PRESENTATIONAL_ATTRIBUTES: [ "align", "background", "bgcolor", "border", "cellpadding", "cellspacing", "frame", "hspace", "rules", "style", "valign", "vspace" ],
-
-  DEPRECATED_SIZE_ATTRIBUTE_ELEMS: [ "TABLE", "TH", "TD", "HR", "PRE" ],
-
-  // The commented out elements qualify as phrasing content but tend to be
-  // removed by readability when put into paragraphs, so we ignore them here.
-  PHRASING_ELEMS: [
-    // "CANVAS", "IFRAME", "SVG", "VIDEO",
-    "ABBR", "AUDIO", "B", "BDO", "BR", "BUTTON", "CITE", "CODE", "DATA",
-    "DATALIST", "DFN", "EM", "EMBED", "I", "IMG", "INPUT", "KBD", "LABEL",
-    "MARK", "MATH", "METER", "NOSCRIPT", "OBJECT", "OUTPUT", "PROGRESS", "Q",
-    "RUBY", "SAMP", "SCRIPT", "SELECT", "SMALL", "SPAN", "STRONG", "SUB",
-    "SUP", "TEXTAREA", "TIME", "VAR", "WBR"
-  ],
-
-  // These are the classes that readability sets itself.
-  CLASSES_TO_PRESERVE: [ "page" ],
-
-  /**
-   * Run any post-process modifications to article content as necessary.
-   *
-   * @param Element
-   * @return void
-  **/
-  _postProcessContent: function(articleContent) {
-    // Readability cannot open relative uris so we convert them to absolute uris.
-    this._fixRelativeUris(articleContent);
-
-    // Remove classes.
-    this._cleanClasses(articleContent);
-  },
-
-  /**
-   * Iterates over a NodeList, calls `filterFn` for each node and removes node
-   * if function returned `true`.
-   *
-   * If function is not passed, removes all the nodes in node list.
-   *
-   * @param NodeList nodeList The nodes to operate on
-   * @param Function filterFn the function to use as a filter
-   * @return void
-   */
-  _removeNodes: function(nodeList, filterFn) {
-    for (var i = nodeList.length - 1; i >= 0; i--) {
-      var node = nodeList[i];
-      var parentNode = node.parentNode;
-      if (parentNode) {
-        if (!filterFn || filterFn.call(this, node, i, nodeList)) {
-          parentNode.removeChild(node);
-        }
-      }
-    }
-  },
-
-  /**
-   * Iterates over a NodeList, and calls _setNodeTag for each node.
-   *
-   * @param NodeList nodeList The nodes to operate on
-   * @param String newTagName the new tag name to use
-   * @return void
-   */
-  _replaceNodeTags: function(nodeList, newTagName) {
-    for (var i = nodeList.length - 1; i >= 0; i--) {
-      var node = nodeList[i];
-      this._setNodeTag(node, newTagName);
-    }
-  },
-
-  /**
-   * Iterate over a NodeList, which doesn't natively fully implement the Array
-   * interface.
-   *
-   * For convenience, the current object context is applied to the provided
-   * iterate function.
-   *
-   * @param  NodeList nodeList The NodeList.
-   * @param  Function fn       The iterate function.
-   * @return void
-   */
-  _forEachNode: function(nodeList, fn) {
-    Array.prototype.forEach.call(nodeList, fn, this);
-  },
-
-  /**
-   * Iterate over a NodeList, return true if any of the provided iterate
-   * function calls returns true, false otherwise.
-   *
-   * For convenience, the current object context is applied to the
-   * provided iterate function.
-   *
-   * @param  NodeList nodeList The NodeList.
-   * @param  Function fn       The iterate function.
-   * @return Boolean
-   */
-  _someNode: function(nodeList, fn) {
-    return Array.prototype.some.call(nodeList, fn, this);
-  },
+/**
+ * Decides whether or not the document is reader-able without parsing the whole thing.
+ *
+ * @return boolean Whether or not we suspect Readability.parse() will suceeed at returning an article object.
+ */
+function isProbablyReaderable(doc, isVisible) {
+  if (!isVisible) {
+    isVisible = isNodeVisible;
+  }
 
-  /**
-   * Iterate over a NodeList, return true if all of the provided iterate
-   * function calls return true, false otherwise.
-   *
-   * For convenience, the current object context is applied to the
-   * provided iterate function.
-   *
-   * @param  NodeList nodeList The NodeList.
-   * @param  Function fn       The iterate function.
-   * @return Boolean
-   */
-  _everyNode: function(nodeList, fn) {
-    return Array.prototype.every.call(nodeList, fn, this);
-  },
-
-  /**
-   * Concat all nodelists passed as arguments.
-   *
-   * @return ...NodeList
-   * @return Array
-   */
-  _concatNodeLists: function() {
-    var slice = Array.prototype.slice;
-    var args = slice.call(arguments);
-    var nodeLists = args.map(function(list) {
-      return slice.call(list);
-    });
-    return Array.prototype.concat.apply([], nodeLists);
-  },
-
-  _getAllNodesWithTag: function(node, tagNames) {
-    if (node.querySelectorAll) {
-      return node.querySelectorAll(tagNames.join(","));
-    }
-    return [].concat.apply([], tagNames.map(function(tag) {
-      var collection = node.getElementsByTagName(tag);
-      return Array.isArray(collection) ? collection : Array.from(collection);
-    }));
-  },
-
-  /**
-   * Removes the class="" attribute from every element in the given
-   * subtree, except those that match CLASSES_TO_PRESERVE and
-   * the classesToPreserve array from the options object.
-   *
-   * @param Element
-   * @return void
-   */
-  _cleanClasses: function(node) {
-    var classesToPreserve = this._classesToPreserve;
-    var className = (node.getAttribute("class") || "")
-      .split(/\s+/)
-      .filter(function(cls) {
-        return classesToPreserve.indexOf(cls) != -1;
-      })
-      .join(" ");
-
-    if (className) {
-      node.setAttribute("class", className);
-    } else {
-      node.removeAttribute("class");
-    }
-
-    for (node = node.firstElementChild; node; node = node.nextElementSibling) {
-      this._cleanClasses(node);
-    }
-  },
-
-  /**
-   * Converts each <a> and <img> uri in the given element to an absolute URI,
-   * ignoring #ref URIs.
-   *
-   * @param Element
-   * @return void
-   */
-  _fixRelativeUris: function(articleContent) {
-    var baseURI = this._doc.baseURI;
-    var documentURI = this._doc.documentURI;
-    function toAbsoluteURI(uri) {
-      // Leave hash links alone if the base URI matches the document URI:
-      if (baseURI == documentURI && uri.charAt(0) == "#") {
-        return uri;
-      }
-      // Otherwise, resolve against base URI:
-      try {
-        return new URL(uri, baseURI).href;
-      } catch (ex) {
-        // Something went wrong, just return the original:
-      }
-      return uri;
-    }
-
-    var links = articleContent.getElementsByTagName("a");
-    this._forEachNode(links, function(link) {
-      var href = link.getAttribute("href");
-      if (href) {
-        // Replace links with javascript: URIs with text content, since
-        // they won't work after scripts have been removed from the page.
-        if (href.indexOf("javascript:") === 0) {
-          var text = this._doc.createTextNode(link.textContent);
-          link.parentNode.replaceChild(text, link);
-        } else {
-          link.setAttribute("href", toAbsoluteURI(href));
-        }
-      }
-    });
-
-    var imgs = articleContent.getElementsByTagName("img");
-    this._forEachNode(imgs, function(img) {
-      var src = img.getAttribute("src");
-      if (src) {
-        img.setAttribute("src", toAbsoluteURI(src));
-      }
-    });
-  },
-
-  /**
-   * Get the article title as an H1.
-   *
-   * @return void
-   **/
-  _getArticleTitle: function() {
-    var doc = this._doc;
-    var curTitle = "";
-    var origTitle = "";
-
-    try {
-      curTitle = origTitle = doc.title.trim();
-
-      // If they had an element with id "title" in their HTML
-      if (typeof curTitle !== "string")
-        curTitle = origTitle = this._getInnerText(doc.getElementsByTagName("title")[0]);
-    } catch (e) {/* ignore exceptions setting the title. */}
-
-    var titleHadHierarchicalSeparators = false;
-    function wordCount(str) {
-      return str.split(/\s+/).length;
-    }
-
-    // If there's a separator in the title, first remove the final part
-    if ((/ [\|\-\\\/>»] /).test(curTitle)) {
-      titleHadHierarchicalSeparators = / [\\\/>»] /.test(curTitle);
-      curTitle = origTitle.replace(/(.*)[\|\-\\\/>»] .*/gi, "$1");
-
-      // If the resulting title is too short (3 words or fewer), remove
-      // the first part instead:
-      if (wordCount(curTitle) < 3)
-        curTitle = origTitle.replace(/[^\|\-\\\/>»]*[\|\-\\\/>»](.*)/gi, "$1");
-    } else if (curTitle.indexOf(": ") !== -1) {
-      // Check if we have an heading containing this exact string, so we
-      // could assume it's the full title.
-      var headings = this._concatNodeLists(
-        doc.getElementsByTagName("h1"),
-        doc.getElementsByTagName("h2")
-      );
-      var trimmedTitle = curTitle.trim();
-      var match = this._someNode(headings, function(heading) {
-        return heading.textContent.trim() === trimmedTitle;
-      });
-
-      // If we don't, let's extract the title out of the original title string.
-      if (!match) {
-        curTitle = origTitle.substring(origTitle.lastIndexOf(":") + 1);
+  var nodes = doc.querySelectorAll("p, pre");
 
-        // If the title is now too short, try the first colon instead:
-        if (wordCount(curTitle) < 3) {
-          curTitle = origTitle.substring(origTitle.indexOf(":") + 1);
-          // But if we have too many words before the colon there's something weird
-          // with the titles and the H tags so let's just use the original title instead
-        } else if (wordCount(origTitle.substr(0, origTitle.indexOf(":"))) > 5) {
-          curTitle = origTitle;
-        }
-      }
-    } else if (curTitle.length > 150 || curTitle.length < 15) {
-      var hOnes = doc.getElementsByTagName("h1");
-
-      if (hOnes.length === 1)
-        curTitle = this._getInnerText(hOnes[0]);
-    }
-
-    curTitle = curTitle.trim();
-    // If we now have 4 words or fewer as our title, and either no
-    // 'hierarchical' separators (\, /, > or ») were found in the original
-    // title or we decreased the number of words by more than 1 word, use
-    // the original title.
-    var curTitleWordCount = wordCount(curTitle);
-    if (curTitleWordCount <= 4 &&
-        (!titleHadHierarchicalSeparators ||
-         curTitleWordCount != wordCount(origTitle.replace(/[\|\-\\\/>»]+/g, "")) - 1)) {
-      curTitle = origTitle;
-    }
-
-    return curTitle;
-  },
-
-  /**
-   * Prepare the HTML document for readability to scrape it.
-   * This includes things like stripping javascript, CSS, and handling terrible markup.
-   *
-   * @return void
-   **/
-  _prepDocument: function() {
-    var doc = this._doc;
-
-    // Remove all style tags in head
-    this._removeNodes(doc.getElementsByTagName("style"));
-
-    if (doc.body) {
-      this._replaceBrs(doc.body);
-    }
-
-    this._replaceNodeTags(doc.getElementsByTagName("font"), "SPAN");
-  },
-
-  /**
-   * Finds the next element, starting from the given node, and ignoring
-   * whitespace in between. If the given node is an element, the same node is
-   * returned.
-   */
-  _nextElement: function (node) {
-    var next = node;
-    while (next
-        && (next.nodeType != this.ELEMENT_NODE)
-        && this.REGEXPS.whitespace.test(next.textContent)) {
-      next = next.nextSibling;
-    }
-    return next;
-  },
-
-  /**
-   * Replaces 2 or more successive <br> elements with a single <p>.
-   * Whitespace between <br> elements are ignored. For example:
-   *   <div>foo<br>bar<br> <br><br>abc</div>
-   * will become:
-   *   <div>foo<br>bar<p>abc</p></div>
-   */
-  _replaceBrs: function (elem) {
-    this._forEachNode(this._getAllNodesWithTag(elem, ["br"]), function(br) {
-      var next = br.nextSibling;
-
-      // Whether 2 or more <br> elements have been found and replaced with a
-      // <p> block.
-      var replaced = false;
-
-      // If we find a <br> chain, remove the <br>s until we hit another element
-      // or non-whitespace. This leaves behind the first <br> in the chain
-      // (which will be replaced with a <p> later).
-      while ((next = this._nextElement(next)) && (next.tagName == "BR")) {
-        replaced = true;
-        var brSibling = next.nextSibling;
-        next.parentNode.removeChild(next);
-        next = brSibling;
-      }
-
-      // If we removed a <br> chain, replace the remaining <br> with a <p>. Add
-      // all sibling nodes as children of the <p> until we hit another <br>
-      // chain.
-      if (replaced) {
-        var p = this._doc.createElement("p");
-        br.parentNode.replaceChild(p, br);
-
-        next = p.nextSibling;
-        while (next) {
-          // If we've hit another <br><br>, we're done adding children to this <p>.
-          if (next.tagName == "BR") {
-            var nextElem = this._nextElement(next.nextSibling);
-            if (nextElem && nextElem.tagName == "BR")
-              break;
-          }
-
-          if (!this._isPhrasingContent(next))
-            break;
-
-          // Otherwise, make this node a child of the new <p>.
-          var sibling = next.nextSibling;
-          p.appendChild(next);
-          next = sibling;
-        }
-
-        while (p.lastChild && this._isWhitespace(p.lastChild)) {
-          p.removeChild(p.lastChild);
-        }
-
-        if (p.parentNode.tagName === "P")
-          this._setNodeTag(p.parentNode, "DIV");
-      }
+  // Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
+  // Some articles' DOM structures might look like
+  // <div>
+  //   Sentences<br>
+  //   <br>
+  //   Sentences<br>
+  // </div>
+  var brNodes = doc.querySelectorAll("div > br");
+  if (brNodes.length) {
+    var set = new Set(nodes);
+    [].forEach.call(brNodes, function(node) {
+      set.add(node.parentNode);
     });
-  },
-
-  _setNodeTag: function (node, tag) {
-    this.log("_setNodeTag", node, tag);
-    if (node.__JSDOMParser__) {
-      node.localName = tag.toLowerCase();
-      node.tagName = tag.toUpperCase();
-      return node;
-    }
-
-    var replacement = node.ownerDocument.createElement(tag);
-    while (node.firstChild) {
-      replacement.appendChild(node.firstChild);
-    }
-    node.parentNode.replaceChild(replacement, node);
-    if (node.readability)
-      replacement.readability = node.readability;
-
-    for (var i = 0; i < node.attributes.length; i++) {
-      replacement.setAttribute(node.attributes[i].name, node.attributes[i].value);
-    }
-    return replacement;
-  },
-
-  /**
-   * Prepare the article node for display. Clean out any inline styles,
-   * iframes, forms, strip extraneous <p> tags, etc.
-   *
-   * @param Element
-   * @return void
-   **/
-  _prepArticle: function(articleContent) {
-    this._cleanStyles(articleContent);
+    nodes = Array.from(set);
+  }
 
-    // Check for data tables before we continue, to avoid removing items in
-    // those tables, which will often be isolated even though they're
-    // visually linked to other content-ful elements (text, images, etc.).
-    this._markDataTables(articleContent);
-
-    // Clean out junk from the article content
-    this._cleanConditionally(articleContent, "form");
-    this._cleanConditionally(articleContent, "fieldset");
-    this._clean(articleContent, "object");
-    this._clean(articleContent, "embed");
-    this._clean(articleContent, "h1");
-    this._clean(articleContent, "footer");
-    this._clean(articleContent, "link");
-    this._clean(articleContent, "aside");
-
-    // Clean out elements have "share" in their id/class combinations from final top candidates,
-    // which means we don't remove the top candidates even they have "share".
-    this._forEachNode(articleContent.children, function(topCandidate) {
-      this._cleanMatchedNodes(topCandidate, /share/);
-    });
-
-    // If there is only one h2 and its text content substantially equals article title,
-    // they are probably using it as a header and not a subheader,
-    // so remove it since we already extract the title separately.
-    var h2 = articleContent.getElementsByTagName("h2");
-    if (h2.length === 1) {
-      var lengthSimilarRate = (h2[0].textContent.length - this._articleTitle.length) / this._articleTitle.length;
-      if (Math.abs(lengthSimilarRate) < 0.5) {
-        var titlesMatch = false;
-        if (lengthSimilarRate > 0) {
-          titlesMatch = h2[0].textContent.includes(this._articleTitle);
-        } else {
-          titlesMatch = this._articleTitle.includes(h2[0].textContent);
-        }
-        if (titlesMatch) {
-          this._clean(articleContent, "h2");
-        }
-      }
-    }
-
-    this._clean(articleContent, "iframe");
-    this._clean(articleContent, "input");
-    this._clean(articleContent, "textarea");
-    this._clean(articleContent, "select");
-    this._clean(articleContent, "button");
-    this._cleanHeaders(articleContent);
-
-    // Do these last as the previous stuff may have removed junk
-    // that will affect these
-    this._cleanConditionally(articleContent, "table");
-    this._cleanConditionally(articleContent, "ul");
-    this._cleanConditionally(articleContent, "div");
-
-    // Remove extra paragraphs
-    this._removeNodes(articleContent.getElementsByTagName("p"), function (paragraph) {
-      var imgCount = paragraph.getElementsByTagName("img").length;
-      var embedCount = paragraph.getElementsByTagName("embed").length;
-      var objectCount = paragraph.getElementsByTagName("object").length;
-      // At this point, nasty iframes have been removed, only remain embedded video ones.
-      var iframeCount = paragraph.getElementsByTagName("iframe").length;
-      var totalCount = imgCount + embedCount + objectCount + iframeCount;
-
-      return totalCount === 0 && !this._getInnerText(paragraph, false);
-    });
-
-    this._forEachNode(this._getAllNodesWithTag(articleContent, ["br"]), function(br) {
-      var next = this._nextElement(br.nextSibling);
-      if (next && next.tagName == "P")
-        br.parentNode.removeChild(br);
-    });
+  var score = 0;
+  // This is a little cheeky, we use the accumulator 'score' to decide what to return from
+  // this callback:
+  return [].some.call(nodes, function(node) {
+    if (!isVisible(node))
+      return false;
 
-    // Remove single-cell tables
-    this._forEachNode(this._getAllNodesWithTag(articleContent, ["table"]), function(table) {
-      var tbody = this._hasSingleTagInsideElement(table, "TBODY") ? table.firstElementChild : table;
-      if (this._hasSingleTagInsideElement(tbody, "TR")) {
-        var row = tbody.firstElementChild;
-        if (this._hasSingleTagInsideElement(row, "TD")) {
-          var cell = row.firstElementChild;
-          cell = this._setNodeTag(cell, this._everyNode(cell.childNodes, this._isPhrasingContent) ? "P" : "DIV");
-          table.parentNode.replaceChild(cell, table);
-        }
-      }
-    });
-  },
-
-  /**
-   * Initialize a node with the readability object. Also checks the
-   * className/id for special names to add to its score.
-   *
-   * @param Element
-   * @return void
-  **/
-  _initializeNode: function(node) {
-    node.readability = {"contentScore": 0};
-
-    switch (node.tagName) {
-      case "DIV":
-        node.readability.contentScore += 5;
-        break;
-
-      case "PRE":
-      case "TD":
-      case "BLOCKQUOTE":
-        node.readability.contentScore += 3;
-        break;
-
-      case "ADDRESS":
-      case "OL":
-      case "UL":
-      case "DL":
-      case "DD":
-      case "DT":
-      case "LI":
-      case "FORM":
-        node.readability.contentScore -= 3;
-        break;
-
-      case "H1":
-      case "H2":
-      case "H3":
-      case "H4":
-      case "H5":
-      case "H6":
-      case "TH":
-        node.readability.contentScore -= 5;
-        break;
-    }
-
-    node.readability.contentScore += this._getClassWeight(node);
-  },
-
-  _removeAndGetNext: function(node) {
-    var nextNode = this._getNextNode(node, true);
-    node.parentNode.removeChild(node);
-    return nextNode;
-  },
-
-  /**
-   * Traverse the DOM from node to node, starting at the node passed in.
-   * Pass true for the second parameter to indicate this node itself
-   * (and its kids) are going away, and we want the next node over.
-   *
-   * Calling this in a loop will traverse the DOM depth-first.
-   */
-  _getNextNode: function(node, ignoreSelfAndKids) {
-    // First check for kids if those aren't being ignored
-    if (!ignoreSelfAndKids && node.firstElementChild) {
-      return node.firstElementChild;
-    }
-    // Then for siblings...
-    if (node.nextElementSibling) {
-      return node.nextElementSibling;
-    }
-    // And finally, move up the parent chain *and* find a sibling
-    // (because this is depth-first traversal, we will have already
-    // seen the parent nodes themselves).
-    do {
-      node = node.parentNode;
-    } while (node && !node.nextElementSibling);
-    return node && node.nextElementSibling;
-  },
-
-  _checkByline: function(node, matchString) {
-    if (this._articleByline) {
+    var matchString = node.className + " " + node.id;
+    if (REGEXPS.unlikelyCandidates.test(matchString) &&
+        !REGEXPS.okMaybeItsACandidate.test(matchString)) {
       return false;
     }
 
-    if (node.getAttribute !== undefined) {
-      var rel = node.getAttribute("rel");
-    }
-
-    if ((rel === "author" || this.REGEXPS.byline.test(matchString)) && this._isValidByline(node.textContent)) {
-      this._articleByline = node.textContent.trim();
-      return true;
-    }
-
-    return false;
-  },
-
-  _getNodeAncestors: function(node, maxDepth) {
-    maxDepth = maxDepth || 0;
-    var i = 0, ancestors = [];
-    while (node.parentNode) {
-      ancestors.push(node.parentNode);
-      if (maxDepth && ++i === maxDepth)
-        break;
-      node = node.parentNode;
-    }
-    return ancestors;
-  },
-
-  /***
-   * grabArticle - Using a variety of metrics (content score, classname, element types), find the content that is
-   *         most likely to be the stuff a user wants to read. Then return it wrapped up in a div.
-   *
-   * @param page a document to run upon. Needs to be a full document, complete with body.
-   * @return Element
-  **/
-  _grabArticle: function (page) {
-    this.log("**** grabArticle ****");
-    var doc = this._doc;
-    var isPaging = (page !== null ? true: false);
-    page = page ? page : this._doc.body;
-
-    // We can't grab an article if we don't have a page!
-    if (!page) {
-      this.log("No body found in document. Abort.");
-      return null;
+    if (node.matches("li p")) {
+      return false;
     }
 
-    var pageCacheHtml = page.innerHTML;
-
-    while (true) {
-      var stripUnlikelyCandidates = this._flagIsActive(this.FLAG_STRIP_UNLIKELYS);
-
-      // First, node prepping. Trash nodes that look cruddy (like ones with the
-      // class name "comment", etc), and turn divs into P tags where they have been
-      // used inappropriately (as in, where they contain no other block level elements.)
-      var elementsToScore = [];
-      var node = this._doc.documentElement;
-
-      while (node) {
-        var matchString = node.className + " " + node.id;
-
-        if (!this._isProbablyVisible(node)) {
-          this.log("Removing hidden node - " + matchString);
-          node = this._removeAndGetNext(node);
-          continue;
-        }
-
-        // Check to see if this node is a byline, and remove it if it is.
-        if (this._checkByline(node, matchString)) {
-          node = this._removeAndGetNext(node);
-          continue;
-        }
-
-        // Remove unlikely candidates
-        if (stripUnlikelyCandidates) {
-          if (this.REGEXPS.unlikelyCandidates.test(matchString) &&
-              !this.REGEXPS.okMaybeItsACandidate.test(matchString) &&
-              node.tagName !== "BODY" &&
-              node.tagName !== "A") {
-            this.log("Removing unlikely candidate - " + matchString);
-            node = this._removeAndGetNext(node);
-            continue;
-          }
-        }
-
-        // Remove DIV, SECTION, and HEADER nodes without any content(e.g. text, image, video, or iframe).
-        if ((node.tagName === "DIV" || node.tagName === "SECTION" || node.tagName === "HEADER" ||
-             node.tagName === "H1" || node.tagName === "H2" || node.tagName === "H3" ||
-             node.tagName === "H4" || node.tagName === "H5" || node.tagName === "H6") &&
-            this._isElementWithoutContent(node)) {
-          node = this._removeAndGetNext(node);
-          continue;
-        }
-
-        if (this.DEFAULT_TAGS_TO_SCORE.indexOf(node.tagName) !== -1) {
-          elementsToScore.push(node);
-        }
-
-        // Turn all divs that don't have children block level elements into p's
-        if (node.tagName === "DIV") {
-          // Put phrasing content into paragraphs.
-          var p = null;
-          var childNode = node.firstChild;
-          while (childNode) {
-            var nextSibling = childNode.nextSibling;
-            if (this._isPhrasingContent(childNode)) {
-              if (p !== null) {
-                p.appendChild(childNode);
-              } else if (!this._isWhitespace(childNode)) {
-                p = doc.createElement("p");
-                node.replaceChild(p, childNode);
-                p.appendChild(childNode);
-              }
-            } else if (p !== null) {
-              while (p.lastChild && this._isWhitespace(p.lastChild)) {
-                p.removeChild(p.lastChild);
-              }
-              p = null;
-            }
-            childNode = nextSibling;
-          }
-
-          // Sites like http://mobile.slate.com encloses each paragraph with a DIV
-          // element. DIVs with only a P element inside and no text content can be
-          // safely converted into plain P elements to avoid confusing the scoring
-          // algorithm with DIVs with are, in practice, paragraphs.
-          if (this._hasSingleTagInsideElement(node, "P") && this._getLinkDensity(node) < 0.25) {
-            var newNode = node.children[0];
-            node.parentNode.replaceChild(newNode, node);
-            node = newNode;
-            elementsToScore.push(node);
-          } else if (!this._hasChildBlockElement(node)) {
-            node = this._setNodeTag(node, "P");
-            elementsToScore.push(node);
-          }
-        }
-        node = this._getNextNode(node);
-      }
-
-      /**
-       * Loop through all paragraphs, and assign a score to them based on how content-y they look.
-       * Then add their score to their parent node.
-       *
-       * A score is determined by things like number of commas, class names, etc. Maybe eventually link density.
-      **/
-      var candidates = [];
-      this._forEachNode(elementsToScore, function(elementToScore) {
-        if (!elementToScore.parentNode || typeof(elementToScore.parentNode.tagName) === "undefined")
-          return;
-
-        // If this paragraph is less than 25 characters, don't even count it.
-        var innerText = this._getInnerText(elementToScore);
-        if (innerText.length < 25)
-          return;
-
-        // Exclude nodes with no ancestor.
-        var ancestors = this._getNodeAncestors(elementToScore, 3);
-        if (ancestors.length === 0)
-          return;
-
-        var contentScore = 0;
-
-        // Add a point for the paragraph itself as a base.
-        contentScore += 1;
-
-        // Add points for any commas within this paragraph.
-        contentScore += innerText.split(",").length;
-
-        // For every 100 characters in this paragraph, add another point. Up to 3 points.
-        contentScore += Math.min(Math.floor(innerText.length / 100), 3);
-
-        // Initialize and score ancestors.
-        this._forEachNode(ancestors, function(ancestor, level) {
-          if (!ancestor.tagName || !ancestor.parentNode || typeof(ancestor.parentNode.tagName) === "undefined")
-            return;
-
-          if (typeof(ancestor.readability) === "undefined") {
-            this._initializeNode(ancestor);
-            candidates.push(ancestor);
-          }
-
-          // Node score divider:
-          // - parent:             1 (no division)
-          // - grandparent:        2
-          // - great grandparent+: ancestor level * 3
-          if (level === 0)
-            var scoreDivider = 1;
-          else if (level === 1)
-            scoreDivider = 2;
-          else
-            scoreDivider = level * 3;
-          ancestor.readability.contentScore += contentScore / scoreDivider;
-        });
-      });
-
-      // After we've calculated scores, loop through all of the possible
-      // candidate nodes we found and find the one with the highest score.
-      var topCandidates = [];
-      for (var c = 0, cl = candidates.length; c < cl; c += 1) {
-        var candidate = candidates[c];
-
-        // Scale the final candidates score based on link density. Good content
-        // should have a relatively small link density (5% or less) and be mostly
-        // unaffected by this operation.
-        var candidateScore = candidate.readability.contentScore * (1 - this._getLinkDensity(candidate));
-        candidate.readability.contentScore = candidateScore;
-
-        this.log("Candidate:", candidate, "with score " + candidateScore);
-
-        for (var t = 0; t < this._nbTopCandidates; t++) {
-          var aTopCandidate = topCandidates[t];
-
-          if (!aTopCandidate || candidateScore > aTopCandidate.readability.contentScore) {
-            topCandidates.splice(t, 0, candidate);
-            if (topCandidates.length > this._nbTopCandidates)
-              topCandidates.pop();
-            break;
-          }
-        }
-      }
-
-      var topCandidate = topCandidates[0] || null;
-      var neededToCreateTopCandidate = false;
-      var parentOfTopCandidate;
-
-      // If we still have no top candidate, just use the body as a last resort.
-      // We also have to copy the body node so it is something we can modify.
-      if (topCandidate === null || topCandidate.tagName === "BODY") {
-        // Move all of the page's children into topCandidate
-        topCandidate = doc.createElement("DIV");
-        neededToCreateTopCandidate = true;
-        // Move everything (not just elements, also text nodes etc.) into the container
-        // so we even include text directly in the body:
-        var kids = page.childNodes;
-        while (kids.length) {
-          this.log("Moving child out:", kids[0]);
-          topCandidate.appendChild(kids[0]);
-        }
-
-        page.appendChild(topCandidate);
-
-        this._initializeNode(topCandidate);
-      } else if (topCandidate) {
-        // Find a better top candidate node if it contains (at least three) nodes which belong to `topCandidates` array
-        // and whose scores are quite closed with current `topCandidate` node.
-        var alternativeCandidateAncestors = [];
-        for (var i = 1; i < topCandidates.length; i++) {
-          if (topCandidates[i].readability.contentScore / topCandidate.readability.contentScore >= 0.75) {
-            alternativeCandidateAncestors.push(this._getNodeAncestors(topCandidates[i]));
-          }
-        }
-        var MINIMUM_TOPCANDIDATES = 3;
-        if (alternativeCandidateAncestors.length >= MINIMUM_TOPCANDIDATES) {
-          parentOfTopCandidate = topCandidate.parentNode;
-          while (parentOfTopCandidate.tagName !== "BODY") {
-            var listsContainingThisAncestor = 0;
-            for (var ancestorIndex = 0; ancestorIndex < alternativeCandidateAncestors.length && listsContainingThisAncestor < MINIMUM_TOPCANDIDATES; ancestorIndex++) {
-              listsContainingThisAncestor += Number(alternativeCandidateAncestors[ancestorIndex].includes(parentOfTopCandidate));
-            }
-            if (listsContainingThisAncestor >= MINIMUM_TOPCANDIDATES) {
-              topCandidate = parentOfTopCandidate;
-              break;
-            }
-            parentOfTopCandidate = parentOfTopCandidate.parentNode;
-          }
-        }
-        if (!topCandidate.readability) {
-          this._initializeNode(topCandidate);
-        }
-
-        // Because of our bonus system, parents of candidates might have scores
-        // themselves. They get half of the node. There won't be nodes with higher
-        // scores than our topCandidate, but if we see the score going *up* in the first
-        // few steps up the tree, that's a decent sign that there might be more content
-        // lurking in other places that we want to unify in. The sibling stuff
-        // below does some of that - but only if we've looked high enough up the DOM
-        // tree.
-        parentOfTopCandidate = topCandidate.parentNode;
-        var lastScore = topCandidate.readability.contentScore;
-        // The scores shouldn't get too low.
-        var scoreThreshold = lastScore / 3;
-        while (parentOfTopCandidate.tagName !== "BODY") {
-          if (!parentOfTopCandidate.readability) {
-            parentOfTopCandidate = parentOfTopCandidate.parentNode;
-            continue;
-          }
-          var parentScore = parentOfTopCandidate.readability.contentScore;
-          if (parentScore < scoreThreshold)
-            break;
-          if (parentScore > lastScore) {
-            // Alright! We found a better parent to use.
-            topCandidate = parentOfTopCandidate;
-            break;
-          }
-          lastScore = parentOfTopCandidate.readability.contentScore;
-          parentOfTopCandidate = parentOfTopCandidate.parentNode;
-        }
-
-        // If the top candidate is the only child, use parent instead. This will help sibling
-        // joining logic when adjacent content is actually located in parent's sibling node.
-        parentOfTopCandidate = topCandidate.parentNode;
-        while (parentOfTopCandidate.tagName != "BODY" && parentOfTopCandidate.children.length == 1) {
-          topCandidate = parentOfTopCandidate;
-          parentOfTopCandidate = topCandidate.parentNode;
-        }
-        if (!topCandidate.readability) {
-          this._initializeNode(topCandidate);
-        }
-      }
-
-      // Now that we have the top candidate, look through its siblings for content
-      // that might also be related. Things like preambles, content split by ads
-      // that we removed, etc.
-      var articleContent = doc.createElement("DIV");
-      if (isPaging)
-        articleContent.id = "readability-content";
-
-      var siblingScoreThreshold = Math.max(10, topCandidate.readability.contentScore * 0.2);
-      // Keep potential top candidate's parent node to try to get text direction of it later.
-      parentOfTopCandidate = topCandidate.parentNode;
-      var siblings = parentOfTopCandidate.children;
-
-      for (var s = 0, sl = siblings.length; s < sl; s++) {
-        var sibling = siblings[s];
-        var append = false;
-
-        this.log("Looking at sibling node:", sibling, sibling.readability ? ("with score " + sibling.readability.contentScore) : "");
-        this.log("Sibling has score", sibling.readability ? sibling.readability.contentScore : "Unknown");
-
-        if (sibling === topCandidate) {
-          append = true;
-        } else {
-          var contentBonus = 0;
-
-          // Give a bonus if sibling nodes and top candidates have the example same classname
-          if (sibling.className === topCandidate.className && topCandidate.className !== "")
-            contentBonus += topCandidate.readability.contentScore * 0.2;
-
-          if (sibling.readability &&
-              ((sibling.readability.contentScore + contentBonus) >= siblingScoreThreshold)) {
-            append = true;
-          } else if (sibling.nodeName === "P") {
-            var linkDensity = this._getLinkDensity(sibling);
-            var nodeContent = this._getInnerText(sibling);
-            var nodeLength = nodeContent.length;
-
-            if (nodeLength > 80 && linkDensity < 0.25) {
-              append = true;
-            } else if (nodeLength < 80 && nodeLength > 0 && linkDensity === 0 &&
-                       nodeContent.search(/\.( |$)/) !== -1) {
-              append = true;
-            }
-          }
-        }
-
-        if (append) {
-          this.log("Appending node:", sibling);
-
-          if (this.ALTER_TO_DIV_EXCEPTIONS.indexOf(sibling.nodeName) === -1) {
-            // We have a node that isn't a common block level element, like a form or td tag.
-            // Turn it into a div so it doesn't get filtered out later by accident.
-            this.log("Altering sibling:", sibling, "to div.");
-
-            sibling = this._setNodeTag(sibling, "DIV");
-          }
-
-          articleContent.appendChild(sibling);
-          // siblings is a reference to the children array, and
-          // sibling is removed from the array when we call appendChild().
-          // As a result, we must revisit this index since the nodes
-          // have been shifted.
-          s -= 1;
-          sl -= 1;
-        }
-      }
-
-      if (this._debug)
-        this.log("Article content pre-prep: " + articleContent.innerHTML);
-      // So we have all of the content that we need. Now we clean it up for presentation.
-      this._prepArticle(articleContent);
-      if (this._debug)
-        this.log("Article content post-prep: " + articleContent.innerHTML);
-
-      if (neededToCreateTopCandidate) {
-        // We already created a fake div thing, and there wouldn't have been any siblings left
-        // for the previous loop, so there's no point trying to create a new div, and then
-        // move all the children over. Just assign IDs and class names here. No need to append
-        // because that already happened anyway.
-        topCandidate.id = "readability-page-1";
-        topCandidate.className = "page";
-      } else {
-        var div = doc.createElement("DIV");
-        div.id = "readability-page-1";
-        div.className = "page";
-        var children = articleContent.childNodes;
-        while (children.length) {
-          div.appendChild(children[0]);
-        }
-        articleContent.appendChild(div);
-      }
-
-      if (this._debug)
-        this.log("Article content after paging: " + articleContent.innerHTML);
-
-      var parseSuccessful = true;
-
-      // Now that we've gone through the full algorithm, check to see if
-      // we got any meaningful content. If we didn't, we may need to re-run
-      // grabArticle with different flags set. This gives us a higher likelihood of
-      // finding the content, and the sieve approach gives us a higher likelihood of
-      // finding the -right- content.
-      var textLength = this._getInnerText(articleContent, true).length;
-      if (textLength < this._charThreshold) {
-        parseSuccessful = false;
-        page.innerHTML = pageCacheHtml;
-
-        if (this._flagIsActive(this.FLAG_STRIP_UNLIKELYS)) {
-          this._removeFlag(this.FLAG_STRIP_UNLIKELYS);
-          this._attempts.push({articleContent: articleContent, textLength: textLength});
-        } else if (this._flagIsActive(this.FLAG_WEIGHT_CLASSES)) {
-          this._removeFlag(this.FLAG_WEIGHT_CLASSES);
-          this._attempts.push({articleContent: articleContent, textLength: textLength});
-        } else if (this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY)) {
-          this._removeFlag(this.FLAG_CLEAN_CONDITIONALLY);
-          this._attempts.push({articleContent: articleContent, textLength: textLength});
-        } else {
-          this._attempts.push({articleContent: articleContent, textLength: textLength});
-          // No luck after removing flags, just return the longest text we found during the different loops
-          this._attempts.sort(function (a, b) {
-            return a.textLength < b.textLength;
-          });
-
-          // But first check if we actually have something
-          if (!this._attempts[0].textLength) {
-            return null;
-          }
-
-          articleContent = this._attempts[0].articleContent;
-          parseSuccessful = true;
-        }
-      }
-
-      if (parseSuccessful) {
-        // Find out text direction from ancestors of final top candidate.
-        var ancestors = [parentOfTopCandidate, topCandidate].concat(this._getNodeAncestors(parentOfTopCandidate));
-        this._someNode(ancestors, function(ancestor) {
-          if (!ancestor.tagName)
-            return false;
-          var articleDir = ancestor.getAttribute("dir");
-          if (articleDir) {
-            this._articleDir = articleDir;
-            return true;
-          }
-          return false;
-        });
-        return articleContent;
-      }
-    }
-  },
-
-  /**
-   * Check whether the input string could be a byline.
-   * This verifies that the input is a string, and that the length
-   * is less than 100 chars.
-   *
-   * @param possibleByline {string} - a string to check whether its a byline.
-   * @return Boolean - whether the input string is a byline.
-   */
-  _isValidByline: function(byline) {
-    if (typeof byline == "string" || byline instanceof String) {
-      byline = byline.trim();
-      return (byline.length > 0) && (byline.length < 100);
-    }
-    return false;
-  },
-
-  /**
-   * Attempts to get excerpt and byline metadata for the article.
-   *
-   * @return Object with optional "excerpt" and "byline" properties
-   */
-  _getArticleMetadata: function() {
-    var metadata = {};
-    var values = {};
-    var metaElements = this._doc.getElementsByTagName("meta");
-
-    // property is a space-separated list of values
-    var propertyPattern = /\s*(dc|dcterm|og|twitter)\s*:\s*(author|creator|description|title)\s*/gi;
-
-    // name is a single value
-    var namePattern = /^\s*(?:(dc|dcterm|og|twitter|weibo:(article|webpage))\s*[\.:]\s*)?(author|creator|description|title)\s*$/i;
-
-    // Find description tags.
-    this._forEachNode(metaElements, function(element) {
-      var elementName = element.getAttribute("name");
-      var elementProperty = element.getAttribute("property");
-      var content = element.getAttribute("content");
-      var matches = null;
-      var name = null;
-
-      if (elementProperty) {
-        matches = elementProperty.match(propertyPattern);
-        if (matches) {
-          for (var i = matches.length - 1; i >= 0; i--) {
-            // Convert to lowercase, and remove any whitespace
-            // so we can match below.
-            name = matches[i].toLowerCase().replace(/\s/g, "");
-            // multiple authors
-            values[name] = content.trim();
-          }
-        }
-      }
-      if (!matches && elementName && namePattern.test(elementName)) {
-        name = elementName;
-        if (content) {
-          // Convert to lowercase, remove any whitespace, and convert dots
-          // to colons so we can match below.
-          name = name.toLowerCase().replace(/\s/g, "").replace(/\./g, ":");
-          values[name] = content.trim();
-        }
-      }
-    });
-
-    // get title
-    metadata.title = values["dc:title"] ||
-                     values["dcterm:title"] ||
-                     values["og:title"] ||
-                     values["weibo:article:title"] ||
-                     values["weibo:webpage:title"] ||
-                     values["title"] ||
-                     values["twitter:title"];
-
-    if (!metadata.title) {
-      metadata.title = this._getArticleTitle();
-    }
-
-    // get author
-    metadata.byline = values["dc:creator"] ||
-                      values["dcterm:creator"] ||
-                      values["author"];
-
-    // get description
-    metadata.excerpt = values["dc:description"] ||
-                       values["dcterm:description"] ||
-                       values["og:description"] ||
-                       values["weibo:article:description"] ||
-                       values["weibo:webpage:description"] ||
-                       values["description"] ||
-                       values["twitter:description"];
-
-    return metadata;
-  },
-
-  /**
-   * Removes script tags from the document.
-   *
-   * @param Element
-  **/
-  _removeScripts: function(doc) {
-    this._removeNodes(doc.getElementsByTagName("script"), function(scriptNode) {
-      scriptNode.nodeValue = "";
-      scriptNode.removeAttribute("src");
-      return true;
-    });
-    this._removeNodes(doc.getElementsByTagName("noscript"));
-  },
-
-  /**
-   * Check if this node has only whitespace and a single element with given tag
-   * Returns false if the DIV node contains non-empty text nodes
-   * or if it contains no element with given tag or more than 1 element.
-   *
-   * @param Element
-   * @param string tag of child element
-  **/
-  _hasSingleTagInsideElement: function(element, tag) {
-    // There should be exactly 1 element child with given tag
-    if (element.children.length != 1 || element.children[0].tagName !== tag) {
+    var textContentLength = node.textContent.trim().length;
+    if (textContentLength < 140) {
       return false;
     }
 
-    // And there should be no text nodes with real content
-    return !this._someNode(element.childNodes, function(node) {
-      return node.nodeType === this.TEXT_NODE &&
-             this.REGEXPS.hasContent.test(node.textContent);
-    });
-  },
-
-  _isElementWithoutContent: function(node) {
-    return node.nodeType === this.ELEMENT_NODE &&
-      node.textContent.trim().length == 0 &&
-      (node.children.length == 0 ||
-       node.children.length == node.getElementsByTagName("br").length + node.getElementsByTagName("hr").length);
-  },
-
-  /**
-   * Determine whether element has any children block level elements.
-   *
-   * @param Element
-   */
-  _hasChildBlockElement: function (element) {
-    return this._someNode(element.childNodes, function(node) {
-      return this.DIV_TO_P_ELEMS.indexOf(node.tagName) !== -1 ||
-             this._hasChildBlockElement(node);
-    });
-  },
-
-  /***
-   * Determine if a node qualifies as phrasing content.
-   * https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_categories#Phrasing_content
-  **/
-  _isPhrasingContent: function(node) {
-    return node.nodeType === this.TEXT_NODE || this.PHRASING_ELEMS.indexOf(node.tagName) !== -1 ||
-      ((node.tagName === "A" || node.tagName === "DEL" || node.tagName === "INS") &&
-        this._everyNode(node.childNodes, this._isPhrasingContent));
-  },
-
-  _isWhitespace: function(node) {
-    return (node.nodeType === this.TEXT_NODE && node.textContent.trim().length === 0) ||
-           (node.nodeType === this.ELEMENT_NODE && node.tagName === "BR");
-  },
-
-  /**
-   * Get the inner text of a node - cross browser compatibly.
-   * This also strips out any excess whitespace to be found.
-   *
-   * @param Element
-   * @param Boolean normalizeSpaces (default: true)
-   * @return string
-  **/
-  _getInnerText: function(e, normalizeSpaces) {
-    normalizeSpaces = (typeof normalizeSpaces === "undefined") ? true : normalizeSpaces;
-    var textContent = e.textContent.trim();
-
-    if (normalizeSpaces) {
-      return textContent.replace(this.REGEXPS.normalize, " ");
-    }
-    return textContent;
-  },
-
-  /**
-   * Get the number of times a string s appears in the node e.
-   *
-   * @param Element
-   * @param string - what to split on. Default is ","
-   * @return number (integer)
-  **/
-  _getCharCount: function(e, s) {
-    s = s || ",";
-    return this._getInnerText(e).split(s).length - 1;
-  },
-
-  /**
-   * Remove the style attribute on every e and under.
-   * TODO: Test if getElementsByTagName(*) is faster.
-   *
-   * @param Element
-   * @return void
-  **/
-  _cleanStyles: function(e) {
-    if (!e || e.tagName.toLowerCase() === "svg")
-      return;
-
-    // Remove `style` and deprecated presentational attributes
-    for (var i = 0; i < this.PRESENTATIONAL_ATTRIBUTES.length; i++) {
-      e.removeAttribute(this.PRESENTATIONAL_ATTRIBUTES[i]);
-    }
-
-    if (this.DEPRECATED_SIZE_ATTRIBUTE_ELEMS.indexOf(e.tagName) !== -1) {
-      e.removeAttribute("width");
-      e.removeAttribute("height");
-    }
-
-    var cur = e.firstElementChild;
-    while (cur !== null) {
-      this._cleanStyles(cur);
-      cur = cur.nextElementSibling;
-    }
-  },
+    score += Math.sqrt(textContentLength - 140);
 
-  /**
-   * Get the density of links as a percentage of the content
-   * This is the amount of text that is inside a link divided by the total text in the node.
-   *
-   * @param Element
-   * @return number (float)
-  **/
-  _getLinkDensity: function(element) {
-    var textLength = this._getInnerText(element).length;
-    if (textLength === 0)
-      return 0;
-
-    var linkLength = 0;
-
-    // XXX implement _reduceNodeList?
-    this._forEachNode(element.getElementsByTagName("a"), function(linkNode) {
-      linkLength += this._getInnerText(linkNode).length;
-    });
-
-    return linkLength / textLength;
-  },
-
-  /**
-   * Get an elements class/id weight. Uses regular expressions to tell if this
-   * element looks good or bad.
-   *
-   * @param Element
-   * @return number (Integer)
-  **/
-  _getClassWeight: function(e) {
-    if (!this._flagIsActive(this.FLAG_WEIGHT_CLASSES))
-      return 0;
-
-    var weight = 0;
-
-    // Look for a special classname
-    if (typeof(e.className) === "string" && e.className !== "") {
-      if (this.REGEXPS.negative.test(e.className))
-        weight -= 25;
-
-      if (this.REGEXPS.positive.test(e.className))
-        weight += 25;
-    }
-
-    // Look for a special ID
-    if (typeof(e.id) === "string" && e.id !== "") {
-      if (this.REGEXPS.negative.test(e.id))
-        weight -= 25;
-
-      if (this.REGEXPS.positive.test(e.id))
-        weight += 25;
-    }
-
-    return weight;
-  },
-
-  /**
-   * Clean a node of all elements of type "tag".
-   * (Unless it's a youtube/vimeo video. People love movies.)
-   *
-   * @param Element
-   * @param string tag to clean
-   * @return void
-   **/
-  _clean: function(e, tag) {
-    var isEmbed = ["object", "embed", "iframe"].indexOf(tag) !== -1;
-
-    this._removeNodes(e.getElementsByTagName(tag), function(element) {
-      // Allow youtube and vimeo videos through as people usually want to see those.
-      if (isEmbed) {
-        var attributeValues = [].map.call(element.attributes, function(attr) {
-          return attr.value;
-        }).join("|");
-
-        // First, check the elements attributes to see if any of them contain youtube or vimeo
-        if (this.REGEXPS.videos.test(attributeValues))
-          return false;
-
-        // Then check the elements inside this element for the same.
-        if (this.REGEXPS.videos.test(element.innerHTML))
-          return false;
-      }
-
+    if (score > 20) {
       return true;
-    });
-  },
-
-  /**
-   * Check if a given node has one of its ancestor tag name matching the
-   * provided one.
-   * @param  HTMLElement node
-   * @param  String      tagName
-   * @param  Number      maxDepth
-   * @param  Function    filterFn a filter to invoke to determine whether this node 'counts'
-   * @return Boolean
-   */
-  _hasAncestorTag: function(node, tagName, maxDepth, filterFn) {
-    maxDepth = maxDepth || 3;
-    tagName = tagName.toUpperCase();
-    var depth = 0;
-    while (node.parentNode) {
-      if (maxDepth > 0 && depth > maxDepth)
-        return false;
-      if (node.parentNode.tagName === tagName && (!filterFn || filterFn(node.parentNode)))
-        return true;
-      node = node.parentNode;
-      depth++;
     }
     return false;
-  },
-
-  /**
-   * Return an object indicating how many rows and columns this table has.
-   */
-  _getRowAndColumnCount: function(table) {
-    var rows = 0;
-    var columns = 0;
-    var trs = table.getElementsByTagName("tr");
-    for (var i = 0; i < trs.length; i++) {
-      var rowspan = trs[i].getAttribute("rowspan") || 0;
-      if (rowspan) {
-        rowspan = parseInt(rowspan, 10);
-      }
-      rows += (rowspan || 1);
-
-      // Now look for column-related info
-      var columnsInThisRow = 0;
-      var cells = trs[i].getElementsByTagName("td");
-      for (var j = 0; j < cells.length; j++) {
-        var colspan = cells[j].getAttribute("colspan") || 0;
-        if (colspan) {
-          colspan = parseInt(colspan, 10);
-        }
-        columnsInThisRow += (colspan || 1);
-      }
-      columns = Math.max(columns, columnsInThisRow);
-    }
-    return {rows: rows, columns: columns};
-  },
-
-  /**
-   * Look for 'data' (as opposed to 'layout') tables, for which we use
-   * similar checks as
-   * https://dxr.mozilla.org/mozilla-central/rev/71224049c0b52ab190564d3ea0eab089a159a4cf/accessible/html/HTMLTableAccessible.cpp#920
-   */
-  _markDataTables: function(root) {
-    var tables = root.getElementsByTagName("table");
-    for (var i = 0; i < tables.length; i++) {
-      var table = tables[i];
-      var role = table.getAttribute("role");
-      if (role == "presentation") {
-        table._readabilityDataTable = false;
-        continue;
-      }
-      var datatable = table.getAttribute("datatable");
-      if (datatable == "0") {
-        table._readabilityDataTable = false;
-        continue;
-      }
-      var summary = table.getAttribute("summary");
-      if (summary) {
-        table._readabilityDataTable = true;
-        continue;
-      }
-
-      var caption = table.getElementsByTagName("caption")[0];
-      if (caption && caption.childNodes.length > 0) {
-        table._readabilityDataTable = true;
-        continue;
-      }
-
-      // If the table has a descendant with any of these tags, consider a data table:
-      var dataTableDescendants = ["col", "colgroup", "tfoot", "thead", "th"];
-      var descendantExists = function(tag) {
-        return !!table.getElementsByTagName(tag)[0];
-      };
-      if (dataTableDescendants.some(descendantExists)) {
-        this.log("Data table because found data-y descendant");
-        table._readabilityDataTable = true;
-        continue;
-      }
-
-      // Nested tables indicate a layout table:
-      if (table.getElementsByTagName("table")[0]) {
-        table._readabilityDataTable = false;
-        continue;
-      }
-
-      var sizeInfo = this._getRowAndColumnCount(table);
-      if (sizeInfo.rows >= 10 || sizeInfo.columns > 4) {
-        table._readabilityDataTable = true;
-        continue;
-      }
-      // Now just go by size entirely:
-      table._readabilityDataTable = sizeInfo.rows * sizeInfo.columns > 10;
-    }
-  },
-
-  /**
-   * Clean an element of all tags of type "tag" if they look fishy.
-   * "Fishy" is an algorithm based on content length, classnames, link density, number of images & embeds, etc.
-   *
-   * @return void
-   **/
-  _cleanConditionally: function(e, tag) {
-    if (!this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY))
-      return;
-
-    var isList = tag === "ul" || tag === "ol";
-
-    // Gather counts for other typical elements embedded within.
-    // Traverse backwards so we can remove nodes at the same time
-    // without effecting the traversal.
-    //
-    // TODO: Consider taking into account original contentScore here.
-    this._removeNodes(e.getElementsByTagName(tag), function(node) {
-      // First check if we're in a data table, in which case don't remove us.
-      var isDataTable = function(t) {
-        return t._readabilityDataTable;
-      };
-
-      if (this._hasAncestorTag(node, "table", -1, isDataTable)) {
-        return false;
-      }
-
-      var weight = this._getClassWeight(node);
-      var contentScore = 0;
-
-      this.log("Cleaning Conditionally", node);
-
-      if (weight + contentScore < 0) {
-        return true;
-      }
-
-      if (this._getCharCount(node, ",") < 10) {
-        // If there are not very many commas, and the number of
-        // non-paragraph elements is more than paragraphs or other
-        // ominous signs, remove the element.
-        var p = node.getElementsByTagName("p").length;
-        var img = node.getElementsByTagName("img").length;
-        var li = node.getElementsByTagName("li").length - 100;
-        var input = node.getElementsByTagName("input").length;
-
-        var embedCount = 0;
-        var embeds = node.getElementsByTagName("embed");
-        for (var ei = 0, il = embeds.length; ei < il; ei += 1) {
-          if (!this.REGEXPS.videos.test(embeds[ei].src))
-            embedCount += 1;
-        }
-
-        var linkDensity = this._getLinkDensity(node);
-        var contentLength = this._getInnerText(node).length;
-
-        var haveToRemove =
-          (img > 1 && p / img < 0.5 && !this._hasAncestorTag(node, "figure")) ||
-          (!isList && li > p) ||
-          (input > Math.floor(p/3)) ||
-          (!isList && contentLength < 25 && (img === 0 || img > 2) && !this._hasAncestorTag(node, "figure")) ||
-          (!isList && weight < 25 && linkDensity > 0.2) ||
-          (weight >= 25 && linkDensity > 0.5) ||
-          ((embedCount === 1 && contentLength < 75) || embedCount > 1);
-        return haveToRemove;
-      }
-      return false;
-    });
-  },
+  });
+}
 
-  /**
-   * Clean out elements whose id/class combinations match specific string.
-   *
-   * @param Element
-   * @param RegExp match id/class combination.
-   * @return void
-   **/
-  _cleanMatchedNodes: function(e, regex) {
-    var endOfSearchMarkerNode = this._getNextNode(e, true);
-    var next = this._getNextNode(e);
-    while (next && next != endOfSearchMarkerNode) {
-      if (regex.test(next.className + " " + next.id)) {
-        next = this._removeAndGetNext(next);
-      } else {
-        next = this._getNextNode(next);
-      }
-    }
-  },
-
-  /**
-   * Clean out spurious headers from an Element. Checks things like classnames and link density.
-   *
-   * @param Element
-   * @return void
-  **/
-  _cleanHeaders: function(e) {
-    for (var headerIndex = 1; headerIndex < 3; headerIndex += 1) {
-      this._removeNodes(e.getElementsByTagName("h" + headerIndex), function (header) {
-        return this._getClassWeight(header) < 0;
-      });
-    }
-  },
-
-  _flagIsActive: function(flag) {
-    return (this._flags & flag) > 0;
-  },
-
-  _removeFlag: function(flag) {
-    this._flags = this._flags & ~flag;
-  },
-
-  _isProbablyVisible: function(node) {
-    return node.style.display != "none" && !node.hasAttribute("hidden");
-  },
-
-  /**
-   * Decides whether or not the document is reader-able without parsing the whole thing.
-   *
-   * @return boolean Whether or not we suspect parse() will suceeed at returning an article object.
-   */
-  isProbablyReaderable: function(helperIsVisible) {
-    var nodes = this._getAllNodesWithTag(this._doc, ["p", "pre"]);
-
-    // Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
-    // Some articles' DOM structures might look like
-    // <div>
-    //   Sentences<br>
-    //   <br>
-    //   Sentences<br>
-    // </div>
-    var brNodes = this._getAllNodesWithTag(this._doc, ["div > br"]);
-    if (brNodes.length) {
-      var set = new Set();
-      [].forEach.call(brNodes, function(node) {
-        set.add(node.parentNode);
-      });
-      nodes = [].concat.apply(Array.from(set), nodes);
-    }
-
-    if (!helperIsVisible) {
-      helperIsVisible = this._isProbablyVisible;
-    }
-
-    var score = 0;
-    // This is a little cheeky, we use the accumulator 'score' to decide what to return from
-    // this callback:
-    return this._someNode(nodes, function(node) {
-      if (helperIsVisible && !helperIsVisible(node))
-        return false;
-      var matchString = node.className + " " + node.id;
-
-      if (this.REGEXPS.unlikelyCandidates.test(matchString) &&
-          !this.REGEXPS.okMaybeItsACandidate.test(matchString)) {
-        return false;
-      }
-
-      if (node.matches && node.matches("li p")) {
-        return false;
-      }
-
-      var textContentLength = node.textContent.trim().length;
-      if (textContentLength < 140) {
-        return false;
-      }
-
-      score += Math.sqrt(textContentLength - 140);
-
-      if (score > 20) {
-        return true;
-      }
-      return false;
-    });
-  },
-
-  /**
-   * Runs readability.
-   *
-   * Workflow:
-   *  1. Prep the document by removing script tags, css, etc.
-   *  2. Build readability's DOM tree.
-   *  3. Grab the article content from the current dom tree.
-   *  4. Replace the current DOM tree with the new one.
-   *  5. Read peacefully.
-   *
-   * @return void
-   **/
-  parse: function () {
-    // Avoid parsing too large documents, as per configuration option
-    if (this._maxElemsToParse > 0) {
-      var numTags = this._doc.getElementsByTagName("*").length;
-      if (numTags > this._maxElemsToParse) {
-        throw new Error("Aborting parsing document; " + numTags + " elements found");
-      }
-    }
-
-    // Remove script tags from the document.
-    this._removeScripts(this._doc);
-
-    this._prepDocument();
-
-    var metadata = this._getArticleMetadata();
-    this._articleTitle = metadata.title;
-
-    var articleContent = this._grabArticle();
-    if (!articleContent)
-      return null;
-
-    this.log("Grabbed: " + articleContent.innerHTML);
-
-    this._postProcessContent(articleContent);
-
-    // If we haven't found an excerpt in the article's metadata, use the article's
-    // first paragraph as the excerpt. This is used for displaying a preview of
-    // the article's content.
-    if (!metadata.excerpt) {
-      var paragraphs = articleContent.getElementsByTagName("p");
-      if (paragraphs.length > 0) {
-        metadata.excerpt = paragraphs[0].textContent.trim();
-      }
-    }
-
-    var textContent = articleContent.textContent;
-    return {
-      title: this._articleTitle,
-      byline: metadata.byline || this._articleByline,
-      dir: this._articleDir,
-      content: articleContent.innerHTML,
-      textContent: textContent,
-      length: textContent.length,
-      excerpt: metadata.excerpt,
-    };
-  }
-};
-
-if (typeof module === "object") {
-  module.exports = Readability;
+if (typeof exports === "object") {
+  exports.isProbablyReaderable = isProbablyReaderable;
 }
--- a/toolkit/components/reader/Readability.js
+++ b/toolkit/components/reader/Readability.js
@@ -1,17 +1,10 @@
 /*eslint-env es6:false*/
 /*
- * DO NOT MODIFY THIS FILE DIRECTLY!
- *
- * This is a shared library that is maintained in an external repo:
- * https://github.com/mozilla/readability
- */
-
-/*
  * Copyright (c) 2010 Arc90 Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
@@ -113,18 +106,21 @@ Readability.prototype = {
   DEFAULT_TAGS_TO_SCORE: "section,h2,h3,h4,h5,h6,p,td,pre".toUpperCase().split(","),
 
   // The default number of chars an article must have in order to return a result
   DEFAULT_CHAR_THRESHOLD: 500,
 
   // All of the regular expressions in use within readability.
   // Defined up here so we don't instantiate them repeatedly in loops.
   REGEXPS: {
+    // NOTE: These two regular expressions are duplicated in
+    // Readability-readerable.js. Please keep both copies in sync.
     unlikelyCandidates: /-ad-|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|foot|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
     okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
+
     positive: /article|body|content|entry|hentry|h-entry|main|page|pagination|post|text|blog|story/i,
     negative: /hidden|^hid$| hid$| hid |^hid |banner|combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|share|shoutbox|sidebar|skyscraper|sponsor|shopping|tags|tool|widget/i,
     extraneous: /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,
     byline: /byline|author|dateline|writtenby|p-author/i,
     replaceFonts: /<(\/?)font[^>]*>/gi,
     normalize: /\s{2,}/g,
     videos: /\/\/(www\.)?((dailymotion|youtube|youtube-nocookie|player\.vimeo|v\.qq)\.com|(archive|upload\.wikimedia)\.org|player\.twitch\.tv)/i,
     nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
@@ -1707,75 +1703,16 @@ Readability.prototype = {
     this._flags = this._flags & ~flag;
   },
 
   _isProbablyVisible: function(node) {
     return node.style.display != "none" && !node.hasAttribute("hidden");
   },
 
   /**
-   * Decides whether or not the document is reader-able without parsing the whole thing.
-   *
-   * @return boolean Whether or not we suspect parse() will suceeed at returning an article object.
-   */
-  isProbablyReaderable: function(helperIsVisible) {
-    var nodes = this._getAllNodesWithTag(this._doc, ["p", "pre"]);
-
-    // Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
-    // Some articles' DOM structures might look like
-    // <div>
-    //   Sentences<br>
-    //   <br>
-    //   Sentences<br>
-    // </div>
-    var brNodes = this._getAllNodesWithTag(this._doc, ["div > br"]);
-    if (brNodes.length) {
-      var set = new Set();
-      [].forEach.call(brNodes, function(node) {
-        set.add(node.parentNode);
-      });
-      nodes = [].concat.apply(Array.from(set), nodes);
-    }
-
-    if (!helperIsVisible) {
-      helperIsVisible = this._isProbablyVisible;
-    }
-
-    var score = 0;
-    // This is a little cheeky, we use the accumulator 'score' to decide what to return from
-    // this callback:
-    return this._someNode(nodes, function(node) {
-      if (helperIsVisible && !helperIsVisible(node))
-        return false;
-      var matchString = node.className + " " + node.id;
-
-      if (this.REGEXPS.unlikelyCandidates.test(matchString) &&
-          !this.REGEXPS.okMaybeItsACandidate.test(matchString)) {
-        return false;
-      }
-
-      if (node.matches && node.matches("li p")) {
-        return false;
-      }
-
-      var textContentLength = node.textContent.trim().length;
-      if (textContentLength < 140) {
-        return false;
-      }
-
-      score += Math.sqrt(textContentLength - 140);
-
-      if (score > 20) {
-        return true;
-      }
-      return false;
-    });
-  },
-
-  /**
    * Runs readability.
    *
    * Workflow:
    *  1. Prep the document by removing script tags, css, etc.
    *  2. Build readability's DOM tree.
    *  3. Grab the article content from the current dom tree.
    *  4. Replace the current DOM tree with the new one.
    *  5. Read peacefully.
--- a/toolkit/components/reader/ReaderMode.jsm
+++ b/toolkit/components/reader/ReaderMode.jsm
@@ -36,68 +36,26 @@ ChromeUtils.import("resource://gre/modul
 
 XPCOMUtils.defineLazyGlobalGetters(this, ["XMLHttpRequest", "XMLSerializer"]);
 
 ChromeUtils.defineModuleGetter(this, "CommonUtils", "resource://services-common/utils.js");
 ChromeUtils.defineModuleGetter(this, "EventDispatcher", "resource://gre/modules/Messaging.jsm");
 ChromeUtils.defineModuleGetter(this, "OS", "resource://gre/modules/osfile.jsm");
 ChromeUtils.defineModuleGetter(this, "ReaderWorker", "resource://gre/modules/reader/ReaderWorker.jsm");
 ChromeUtils.defineModuleGetter(this, "LanguageDetector", "resource:///modules/translation/LanguageDetector.jsm");
-
-XPCOMUtils.defineLazyGetter(this, "Readability", function() {
-  let scope = {};
-  scope.dump = this.dump;
-  Services.scriptloader.loadSubScript("resource://gre/modules/reader/Readability.js", scope);
-  return scope.Readability;
-});
+ChromeUtils.defineModuleGetter(this, "Readerable", "resource://gre/modules/Readerable.jsm");
 
 const gIsFirefoxDesktop = Services.appinfo.ID == "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}";
 
 var ReaderMode = {
   // Version of the cache schema.
   CACHE_VERSION: 1,
 
   DEBUG: 0,
 
-  // Don't try to parse the page if it has too many elements (for memory and
-  // performance reasons)
-  get maxElemsToParse() {
-    delete this.parseNodeLimit;
-
-    Services.prefs.addObserver("reader.parse-node-limit", this);
-    return this.parseNodeLimit = Services.prefs.getIntPref("reader.parse-node-limit");
-  },
-
-  get isEnabledForParseOnLoad() {
-    delete this.isEnabledForParseOnLoad;
-
-    // Listen for future pref changes.
-    Services.prefs.addObserver("reader.parse-on-load.", this);
-
-    return this.isEnabledForParseOnLoad = this._getStateForParseOnLoad();
-  },
-
-  _getStateForParseOnLoad() {
-    let isEnabled = Services.prefs.getBoolPref("reader.parse-on-load.enabled");
-    let isForceEnabled = Services.prefs.getBoolPref("reader.parse-on-load.force-enabled");
-    return isForceEnabled || isEnabled;
-  },
-
-  observe(aMessage, aTopic, aData) {
-    switch (aTopic) {
-      case "nsPref:changed":
-        if (aData.startsWith("reader.parse-on-load.")) {
-          this.isEnabledForParseOnLoad = this._getStateForParseOnLoad();
-        } else if (aData === "reader.parse-node-limit") {
-          this.parseNodeLimit = Services.prefs.getIntPref(aData);
-        }
-        break;
-    }
-  },
-
   /**
    * Enter the reader mode by going forward one step in history if applicable,
    * if not, append the about:reader page in the history instead.
    */
   enterReaderMode(docShell, win) {
     let url = win.document.location.href;
     let readerURL = "about:reader?url=" + encodeURIComponent(url);
     let webNav = docShell.QueryInterface(Ci.nsIWebNavigation);
@@ -193,58 +151,26 @@ var ReaderMode = {
       } catch (ex) {
         return null;
       }
     }
     return null;
   },
 
   /**
-   * Decides whether or not a document is reader-able without parsing the whole thing.
-   *
-   * @param doc A document to parse.
-   * @return boolean Whether or not we should show the reader mode button.
-   */
-  isProbablyReaderable(doc) {
-    // Only care about 'real' HTML documents:
-    if (doc.mozSyntheticDocument || !(doc instanceof doc.defaultView.HTMLDocument)) {
-      return false;
-    }
-
-    let uri = Services.io.newURI(doc.location.href);
-    if (!this._shouldCheckUri(uri)) {
-      return false;
-    }
-
-    let utils = this.getUtilsForWin(doc.defaultView);
-    // We pass in a helper function to determine if a node is visible, because
-    // it uses gecko APIs that the engine-agnostic readability code can't rely
-    // upon.
-    return new Readability(doc).isProbablyReaderable(this.isNodeVisible.bind(this, utils));
-  },
-
-  isNodeVisible(utils, node) {
-    let bounds = utils.getBoundsWithoutFlushing(node);
-    return bounds.height > 0 && bounds.width > 0;
-  },
-
-  getUtilsForWin(win) {
-    return win.windowUtils;
-  },
-
-  /**
    * Gets an article from a loaded browser's document. This method will not attempt
    * to parse certain URIs (e.g. about: URIs).
    *
    * @param doc A document to parse.
    * @return {Promise}
    * @resolves JS object representing the article, or null if no article is found.
    */
   parseDocument(doc) {
-    if (!this._shouldCheckUri(doc.documentURIObject) || !this._shouldCheckUri(doc.baseURIObject, true)) {
+    if (!Readerable.shouldCheckUri(doc.documentURIObject) ||
+        !Readerable.shouldCheckUri(doc.baseURIObject, true)) {
       this.log("Reader mode disabled for URI");
       return null;
     }
 
     return this._readerParse(doc);
   },
 
   /**
@@ -254,27 +180,28 @@ var ReaderMode = {
    * @return {Promise}
    * @resolves JS object representing the article, or null if no article is found.
    */
   async downloadAndParseDocument(url) {
     let doc = await this._downloadDocument(url);
     if (!doc) {
       return null;
     }
-    if (!this._shouldCheckUri(doc.documentURIObject) || !this._shouldCheckUri(doc.baseURIObject, true)) {
+    if (!Readerable.shouldCheckUri(doc.documentURIObject) ||
+        !Readerable.shouldCheckUri(doc.baseURIObject, true)) {
       this.log("Reader mode disabled for URI");
       return null;
     }
 
     return this._readerParse(doc);
   },
 
   _downloadDocument(url) {
     try {
-      if (!this._shouldCheckUri(Services.io.newURI(url))) {
+      if (!Readerable.shouldCheckUri(Services.io.newURI(url))) {
         return null;
       }
     } catch (ex) {
       Cu.reportError(new Error(`Couldn't create URI from ${url} to download: ${ex}`));
       return null;
     }
     let histogram = Services.telemetry.getHistogramById("READER_MODE_DOWNLOAD_RESULT");
     return new Promise((resolve, reject) => {
@@ -410,52 +337,16 @@ var ReaderMode = {
     await OS.File.remove(path);
   },
 
   log(msg) {
     if (this.DEBUG)
       dump("Reader: " + msg);
   },
 
-  _blockedHosts: [
-    "amazon.com",
-    "github.com",
-    "mail.google.com",
-    "pinterest.com",
-    "reddit.com",
-    "twitter.com",
-    "youtube.com",
-  ],
-
-  _shouldCheckUri(uri, isBaseUri = false) {
-    if (!(uri.schemeIs("http") || uri.schemeIs("https"))) {
-      this.log("Not parsing URI scheme: " + uri.scheme);
-      return false;
-    }
-
-    try {
-      uri.QueryInterface(Ci.nsIURL);
-    } catch (ex) {
-      // If this doesn't work, presumably the URL is not well-formed or something
-      return false;
-    }
-    // Sadly, some high-profile pages have false positives, so bail early for those:
-    let asciiHost = uri.asciiHost;
-    if (!isBaseUri && this._blockedHosts.some(blockedHost => asciiHost.endsWith(blockedHost))) {
-      return false;
-    }
-
-    if (!isBaseUri && (!uri.filePath || uri.filePath == "/")) {
-      this.log("Not parsing home page: " + uri.spec);
-      return false;
-    }
-
-    return true;
-  },
-
   /**
    * Attempts to parse a document into an article. Heavy lifting happens
    * in readerWorker.js.
    *
    * @param doc The document to parse.
    * @return {Promise}
    * @resolves JS object representing the article, or null if no article is found.
    */
@@ -636,8 +527,11 @@ var ReaderMode = {
       [ "sv", {cpm: 917,  variance: 156 } ],
       [ "tr", {cpm: 1054, variance: 156 } ],
       [ "zh", {cpm: 255,  variance: 29 } ],
     ]);
 
     return readingSpeed.get(lang) || readingSpeed.get("en");
   },
 };
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  ReaderMode, "maxElemsToParse", "reader.parse-node-limit", 0);
copy from toolkit/components/reader/ReaderMode.jsm
copy to toolkit/components/reader/Readerable.js
--- a/toolkit/components/reader/ReaderMode.jsm
+++ b/toolkit/components/reader/Readerable.js
@@ -1,643 +1,79 @@
 // -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 
-var EXPORTED_SYMBOLS = ["ReaderMode"];
-
-// Constants for telemetry.
-const DOWNLOAD_SUCCESS = 0;
-const DOWNLOAD_ERROR_XHR = 1;
-const DOWNLOAD_ERROR_NO_DOC = 2;
-
-const PARSE_SUCCESS = 0;
-const PARSE_ERROR_TOO_MANY_ELEMENTS = 1;
-const PARSE_ERROR_WORKER = 2;
-const PARSE_ERROR_NO_ARTICLE = 3;
+// This file and Readability-readerable.js are merged together into
+// Readerable.jsm.
 
-// Class names to preserve in the readerized output. We preserve these class
-// names so that rules in aboutReader.css can match them.
-const CLASSES_TO_PRESERVE = [
-  "caption",
-  "emoji",
-  "hidden",
-  "invisble",
-  "sr-only",
-  "visually-hidden",
-  "visuallyhidden",
-  "wp-caption",
-  "wp-caption-text",
-  "wp-smiley",
-];
+/* exported Readerable */
+/* import-globals-from Readability-readerable.js */
 
 ChromeUtils.import("resource://gre/modules/Services.jsm");
 ChromeUtils.import("resource://gre/modules/XPCOMUtils.jsm");
 
-XPCOMUtils.defineLazyGlobalGetters(this, ["XMLHttpRequest", "XMLSerializer"]);
-
-ChromeUtils.defineModuleGetter(this, "CommonUtils", "resource://services-common/utils.js");
-ChromeUtils.defineModuleGetter(this, "EventDispatcher", "resource://gre/modules/Messaging.jsm");
-ChromeUtils.defineModuleGetter(this, "OS", "resource://gre/modules/osfile.jsm");
-ChromeUtils.defineModuleGetter(this, "ReaderWorker", "resource://gre/modules/reader/ReaderWorker.jsm");
-ChromeUtils.defineModuleGetter(this, "LanguageDetector", "resource:///modules/translation/LanguageDetector.jsm");
-
-XPCOMUtils.defineLazyGetter(this, "Readability", function() {
-  let scope = {};
-  scope.dump = this.dump;
-  Services.scriptloader.loadSubScript("resource://gre/modules/reader/Readability.js", scope);
-  return scope.Readability;
-});
-
-const gIsFirefoxDesktop = Services.appinfo.ID == "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}";
-
-var ReaderMode = {
-  // Version of the cache schema.
-  CACHE_VERSION: 1,
-
-  DEBUG: 0,
-
-  // Don't try to parse the page if it has too many elements (for memory and
-  // performance reasons)
-  get maxElemsToParse() {
-    delete this.parseNodeLimit;
-
-    Services.prefs.addObserver("reader.parse-node-limit", this);
-    return this.parseNodeLimit = Services.prefs.getIntPref("reader.parse-node-limit");
-  },
-
-  get isEnabledForParseOnLoad() {
-    delete this.isEnabledForParseOnLoad;
-
-    // Listen for future pref changes.
-    Services.prefs.addObserver("reader.parse-on-load.", this);
-
-    return this.isEnabledForParseOnLoad = this._getStateForParseOnLoad();
-  },
-
-  _getStateForParseOnLoad() {
-    let isEnabled = Services.prefs.getBoolPref("reader.parse-on-load.enabled");
-    let isForceEnabled = Services.prefs.getBoolPref("reader.parse-on-load.force-enabled");
-    return isForceEnabled || isEnabled;
-  },
-
-  observe(aMessage, aTopic, aData) {
-    switch (aTopic) {
-      case "nsPref:changed":
-        if (aData.startsWith("reader.parse-on-load.")) {
-          this.isEnabledForParseOnLoad = this._getStateForParseOnLoad();
-        } else if (aData === "reader.parse-node-limit") {
-          this.parseNodeLimit = Services.prefs.getIntPref(aData);
-        }
-        break;
-    }
-  },
-
-  /**
-   * Enter the reader mode by going forward one step in history if applicable,
-   * if not, append the about:reader page in the history instead.
-   */
-  enterReaderMode(docShell, win) {
-    let url = win.document.location.href;
-    let readerURL = "about:reader?url=" + encodeURIComponent(url);
-    let webNav = docShell.QueryInterface(Ci.nsIWebNavigation);
-    let sh = webNav.sessionHistory;
-    if (webNav.canGoForward) {
-      let forwardEntry = sh.legacySHistory.getEntryAtIndex(sh.index + 1);
-      let forwardURL = forwardEntry.URI.spec;
-      if (forwardURL && (forwardURL == readerURL || !readerURL)) {
-        webNav.goForward();
-        return;
-      }
-    }
-
-    win.document.location = readerURL;
-  },
+function isNodeVisible(node) {
+  return node.clientHeight > 0 && node.clientWidth > 0;
+}
 
-  /**
-   * Exit the reader mode by going back one step in history if applicable,
-   * if not, append the original page in the history instead.
-   */
-  leaveReaderMode(docShell, win) {
-    let url = win.document.location.href;
-    let originalURL = this.getOriginalUrl(url);
-    let webNav = docShell.QueryInterface(Ci.nsIWebNavigation);
-    let sh = webNav.sessionHistory;
-    if (webNav.canGoBack) {
-      let prevEntry = sh.legacySHistory.getEntryAtIndex(sh.index - 1);
-      let prevURL = prevEntry.URI.spec;
-      if (prevURL && (prevURL == originalURL || !originalURL)) {
-        webNav.goBack();
-        return;
-      }
-    }
-
-    let referrerURI, principal;
-    try {
-      referrerURI = Services.io.newURI(url);
-      principal = Services.scriptSecurityManager.createCodebasePrincipal(
-        referrerURI, win.document.nodePrincipal.originAttributes);
-    } catch (e) {
-      Cu.reportError(e);
-      return;
-    }
-    let flags = webNav.LOAD_FLAGS_DISALLOW_INHERIT_PRINCIPAL;
-    webNav.loadURI(originalURL, flags, referrerURI, null, null, principal);
-  },
-
-  /**
-   * Returns original URL from an about:reader URL.
-   *
-   * @param url An about:reader URL.
-   * @return The original URL for the article, or null if we did not find
-   *         a properly formatted about:reader URL.
-   */
-  getOriginalUrl(url) {
-    if (!url.startsWith("about:reader?")) {
-      return null;
-    }
-
-    let outerHash = "";
-    try {
-      let uriObj = Services.io.newURI(url);
-      url = uriObj.specIgnoringRef;
-      outerHash = uriObj.ref;
-    } catch (ex) { /* ignore, use the raw string */ }
-
-    let searchParams = new URLSearchParams(url.substring("about:reader?".length));
-    if (!searchParams.has("url")) {
-      return null;
-    }
-    let originalUrl = searchParams.get("url");
-    if (outerHash) {
-      try {
-        let uriObj = Services.io.newURI(originalUrl);
-        uriObj = Services.io.newURI("#" + outerHash, null, uriObj);
-        originalUrl = uriObj.spec;
-      } catch (ex) {}
-    }
-    return originalUrl;
-  },
-
-  getOriginalUrlObjectForDisplay(url) {
-    let originalUrl = this.getOriginalUrl(url);
-    if (originalUrl) {
-      let uriObj;
-      try {
-        uriObj = Services.uriFixup.createFixupURI(originalUrl, Services.uriFixup.FIXUP_FLAG_NONE);
-      } catch (ex) {
-        return null;
-      }
-      try {
-        return Services.uriFixup.createExposableURI(uriObj);
-      } catch (ex) {
-        return null;
-      }
-    }
-    return null;
+var Readerable = {
+  get isEnabledForParseOnLoad() {
+    return this.isEnabled || this.isForceEnabled;
   },
 
   /**
    * Decides whether or not a document is reader-able without parsing the whole thing.
    *
    * @param doc A document to parse.
    * @return boolean Whether or not we should show the reader mode button.
    */
   isProbablyReaderable(doc) {
     // Only care about 'real' HTML documents:
     if (doc.mozSyntheticDocument || !(doc instanceof doc.defaultView.HTMLDocument)) {
       return false;
     }
 
     let uri = Services.io.newURI(doc.location.href);
-    if (!this._shouldCheckUri(uri)) {
+    if (!this.shouldCheckUri(uri)) {
       return false;
     }
 
-    let utils = this.getUtilsForWin(doc.defaultView);
-    // We pass in a helper function to determine if a node is visible, because
-    // it uses gecko APIs that the engine-agnostic readability code can't rely
-    // upon.
-    return new Readability(doc).isProbablyReaderable(this.isNodeVisible.bind(this, utils));
-  },
-
-  isNodeVisible(utils, node) {
-    let bounds = utils.getBoundsWithoutFlushing(node);
-    return bounds.height > 0 && bounds.width > 0;
-  },
-
-  getUtilsForWin(win) {
-    return win.windowUtils;
-  },
-
-  /**
-   * Gets an article from a loaded browser's document. This method will not attempt
-   * to parse certain URIs (e.g. about: URIs).
-   *
-   * @param doc A document to parse.
-   * @return {Promise}
-   * @resolves JS object representing the article, or null if no article is found.
-   */
-  parseDocument(doc) {
-    if (!this._shouldCheckUri(doc.documentURIObject) || !this._shouldCheckUri(doc.baseURIObject, true)) {
-      this.log("Reader mode disabled for URI");
-      return null;
-    }
-
-    return this._readerParse(doc);
-  },
-
-  /**
-   * Downloads and parses a document from a URL.
-   *
-   * @param url URL to download and parse.
-   * @return {Promise}
-   * @resolves JS object representing the article, or null if no article is found.
-   */
-  async downloadAndParseDocument(url) {
-    let doc = await this._downloadDocument(url);
-    if (!doc) {
-      return null;
-    }
-    if (!this._shouldCheckUri(doc.documentURIObject) || !this._shouldCheckUri(doc.baseURIObject, true)) {
-      this.log("Reader mode disabled for URI");
-      return null;
-    }
-
-    return this._readerParse(doc);
-  },
-
-  _downloadDocument(url) {
-    try {
-      if (!this._shouldCheckUri(Services.io.newURI(url))) {
-        return null;
-      }
-    } catch (ex) {
-      Cu.reportError(new Error(`Couldn't create URI from ${url} to download: ${ex}`));
-      return null;
-    }
-    let histogram = Services.telemetry.getHistogramById("READER_MODE_DOWNLOAD_RESULT");
-    return new Promise((resolve, reject) => {
-      let xhr = new XMLHttpRequest();
-      xhr.open("GET", url, true);
-      xhr.onerror = evt => reject(evt.error);
-      xhr.responseType = "document";
-      xhr.onload = evt => {
-        if (xhr.status !== 200) {
-          reject("Reader mode XHR failed with status: " + xhr.status);
-          histogram.add(DOWNLOAD_ERROR_XHR);
-          return;
-        }
-
-        let doc = xhr.responseXML;
-        if (!doc) {
-          reject("Reader mode XHR didn't return a document");
-          histogram.add(DOWNLOAD_ERROR_NO_DOC);
-          return;
-        }
-
-        // Manually follow a meta refresh tag if one exists.
-        let meta = doc.querySelector("meta[http-equiv=refresh]");
-        if (meta) {
-          let content = meta.getAttribute("content");
-          if (content) {
-            let urlIndex = content.toUpperCase().indexOf("URL=");
-            if (urlIndex > -1) {
-              let baseURI = Services.io.newURI(url);
-              let newURI = Services.io.newURI(content.substring(urlIndex + 4), null, baseURI);
-              let newURL = newURI.spec;
-              let ssm = Services.scriptSecurityManager;
-              let flags = ssm.LOAD_IS_AUTOMATIC_DOCUMENT_REPLACEMENT |
-                          ssm.DISALLOW_INHERIT_PRINCIPAL;
-              try {
-                ssm.checkLoadURIStrWithPrincipal(doc.nodePrincipal, newURL, flags);
-              } catch (ex) {
-                let errorMsg = "Reader mode disallowed meta refresh (reason: " + ex + ").";
-
-                if (Services.prefs.getBoolPref("reader.errors.includeURLs"))
-                  errorMsg += " Refresh target URI: '" + newURL + "'.";
-                reject(errorMsg);
-                return;
-              }
-              // Otherwise, pass an object indicating our new URL:
-              if (!baseURI.equalsExceptRef(newURI)) {
-                reject({newURL});
-                return;
-              }
-            }
-          }
-        }
-        let responseURL = xhr.responseURL;
-        let givenURL = url;
-        // Convert these to real URIs to make sure the escaping (or lack
-        // thereof) is identical:
-        try {
-          responseURL = Services.io.newURI(responseURL).specIgnoringRef;
-        } catch (ex) { /* Ignore errors - we'll use what we had before */ }
-        try {
-          givenURL = Services.io.newURI(givenURL).specIgnoringRef;
-        } catch (ex) { /* Ignore errors - we'll use what we had before */ }
-
-        if (responseURL != givenURL) {
-          // We were redirected without a meta refresh tag.
-          // Force redirect to the correct place:
-          reject({newURL: xhr.responseURL});
-          return;
-        }
-        resolve(doc);
-        histogram.add(DOWNLOAD_SUCCESS);
-      };
-      xhr.send();
-    });
-  },
-
-
-  /**
-   * Retrieves an article from the cache given an article URI.
-   *
-   * @param url The article URL.
-   * @return {Promise}
-   * @resolves JS object representing the article, or null if no article is found.
-   * @rejects OS.File.Error
-   */
-  async getArticleFromCache(url) {
-    let path = this._toHashedPath(url);
-    try {
-      let array = await OS.File.read(path);
-      return JSON.parse(new TextDecoder().decode(array));
-    } catch (e) {
-      if (!(e instanceof OS.File.Error) || !e.becauseNoSuchFile)
-        throw e;
-      return null;
-    }
-  },
-
-  /**
-   * Stores an article in the cache.
-   *
-   * @param article JS object representing article.
-   * @return {Promise}
-   * @resolves When the article is stored.
-   * @rejects OS.File.Error
-   */
-  async storeArticleInCache(article) {
-    let array = new TextEncoder().encode(JSON.stringify(article));
-    let path = this._toHashedPath(article.url);
-    await this._ensureCacheDir();
-    return OS.File.writeAtomic(path, array, { tmpPath: path + ".tmp" })
-      .then(success => {
-        OS.File.stat(path).then(info => {
-          return EventDispatcher.instance.sendRequest({
-            type: "Reader:AddedToCache",
-            url: article.url,
-            size: info.size,
-            path,
-          });
-        });
-      });
-  },
-
-  /**
-   * Removes an article from the cache given an article URI.
-   *
-   * @param url The article URL.
-   * @return {Promise}
-   * @resolves When the article is removed.
-   * @rejects OS.File.Error
-   */
-  async removeArticleFromCache(url) {
-    let path = this._toHashedPath(url);
-    await OS.File.remove(path);
-  },
-
-  log(msg) {
-    if (this.DEBUG)
-      dump("Reader: " + msg);
+    return isProbablyReaderable(doc, isNodeVisible);
   },
 
   _blockedHosts: [
     "amazon.com",
     "github.com",
     "mail.google.com",
     "pinterest.com",
     "reddit.com",
     "twitter.com",
     "youtube.com",
   ],
 
-  _shouldCheckUri(uri, isBaseUri = false) {
-    if (!(uri.schemeIs("http") || uri.schemeIs("https"))) {
-      this.log("Not parsing URI scheme: " + uri.scheme);
+  shouldCheckUri(uri, isBaseUri = false) {
+    if (!["http", "https"].includes(uri.scheme)) {
       return false;
     }
 
-    try {
-      uri.QueryInterface(Ci.nsIURL);
-    } catch (ex) {
-      // If this doesn't work, presumably the URL is not well-formed or something
-      return false;
-    }
-    // Sadly, some high-profile pages have false positives, so bail early for those:
-    let asciiHost = uri.asciiHost;
-    if (!isBaseUri && this._blockedHosts.some(blockedHost => asciiHost.endsWith(blockedHost))) {
-      return false;
-    }
+    if (!isBaseUri) {
+      // Sadly, some high-profile pages have false positives, so bail early for those:
+      let {host} = uri;
+      if (this._blockedHosts.some(blockedHost => host.endsWith(blockedHost))) {
+        return false;
+      }
 
-    if (!isBaseUri && (!uri.filePath || uri.filePath == "/")) {
-      this.log("Not parsing home page: " + uri.spec);
-      return false;
+      if (uri.filePath == "/") {
+        return false;
+      }
     }
 
     return true;
   },
-
-  /**
-   * Attempts to parse a document into an article. Heavy lifting happens
-   * in readerWorker.js.
-   *
-   * @param doc The document to parse.
-   * @return {Promise}
-   * @resolves JS object representing the article, or null if no article is found.
-   */
-  async _readerParse(doc) {
-    let histogram = Services.telemetry.getHistogramById("READER_MODE_PARSE_RESULT");
-    if (this.parseNodeLimit) {
-      let numTags = doc.getElementsByTagName("*").length;
-      if (numTags > this.parseNodeLimit) {
-        this.log("Aborting parse for " + doc.baseURIObject.spec + "; " + numTags + " elements found");
-        histogram.add(PARSE_ERROR_TOO_MANY_ELEMENTS);
-        return null;
-      }
-    }
-
-    // Fetch this here before we send `doc` off to the worker thread, as later on the
-    // document might be nuked but we will still want the URI.
-    let {documentURI} = doc;
-
-    let uriParam = {
-      spec: doc.baseURIObject.spec,
-      host: doc.baseURIObject.host,
-      prePath: doc.baseURIObject.prePath,
-      scheme: doc.baseURIObject.scheme,
-      pathBase: Services.io.newURI(".", null, doc.baseURIObject).spec,
-    };
-
-    let serializer = new XMLSerializer();
-    let serializedDoc = serializer.serializeToString(doc);
-
-    let options = {
-      classesToPreserve: CLASSES_TO_PRESERVE,
-    };
-
-    let article = null;
-    try {
-      article = await ReaderWorker.post("parseDocument", [uriParam, serializedDoc, options]);
-    } catch (e) {
-      Cu.reportError("Error in ReaderWorker: " + e);
-      histogram.add(PARSE_ERROR_WORKER);
-    }
-
-    // Explicitly null out doc to make it clear it might not be available from this
-    // point on.
-    doc = null;
-
-    if (!article) {
-      this.log("Worker did not return an article");
-      histogram.add(PARSE_ERROR_NO_ARTICLE);
-      return null;
-    }
-
-    // Readability returns a URI object based on the baseURI, but we only care
-    // about the original document's URL from now on. This also avoids spoofing
-    // attempts where the baseURI doesn't match the domain of the documentURI
-    article.url = documentURI;
-    delete article.uri;
-
-    let flags = Ci.nsIDocumentEncoder.OutputSelectionOnly | Ci.nsIDocumentEncoder.OutputAbsoluteLinks;
-    article.title = Cc["@mozilla.org/parserutils;1"].getService(Ci.nsIParserUtils)
-                                                    .convertToPlainText(article.title, flags, 0);
-    if (gIsFirefoxDesktop) {
-      await this._assignLanguage(article);
-      this._maybeAssignTextDirection(article);
-    }
-
-    this._assignReadTime(article);
-
-    histogram.add(PARSE_SUCCESS);
-    return article;
-  },
-
-  get _cryptoHash() {
-    delete this._cryptoHash;
-    return this._cryptoHash = Cc["@mozilla.org/security/hash;1"].createInstance(Ci.nsICryptoHash);
-  },
-
-  get _unicodeConverter() {
-    delete this._unicodeConverter;
-    this._unicodeConverter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
-                              .createInstance(Ci.nsIScriptableUnicodeConverter);
-    this._unicodeConverter.charset = "utf8";
-    return this._unicodeConverter;
-  },
+};
 
-  /**
-   * Calculate the hashed path for a stripped article URL.
-   *
-   * @param url The article URL. This should have referrers removed.
-   * @return The file path to the cached article.
-   */
-  _toHashedPath(url) {
-    let value = this._unicodeConverter.convertToByteArray(url);
-    this._cryptoHash.init(this._cryptoHash.MD5);
-    this._cryptoHash.update(value, value.length);
-
-    let hash = CommonUtils.encodeBase32(this._cryptoHash.finish(false));
-    let fileName = hash.substring(0, hash.indexOf("=")) + ".json";
-    return OS.Path.join(OS.Constants.Path.profileDir, "readercache", fileName);
-  },
-
-  /**
-   * Ensures the cache directory exists.
-   *
-   * @return Promise
-   * @resolves When the cache directory exists.
-   * @rejects OS.File.Error
-   */
-  _ensureCacheDir() {
-    let dir = OS.Path.join(OS.Constants.Path.profileDir, "readercache");
-    return OS.File.exists(dir).then(exists => {
-      if (!exists) {
-        return OS.File.makeDir(dir);
-      }
-      return undefined;
-    });
-  },
-
-  /**
-   * Sets a global language string value if the result is confident
-   *
-   * @return Promise
-   * @resolves when the language is detected
-   */
-  _assignLanguage(article) {
-    return LanguageDetector.detectLanguage(article.textContent).then(result => {
-      article.language = result.confident ? result.language : null;
-    });
-  },
-
-  _maybeAssignTextDirection(article) {
-    // TODO: Remove the hardcoded language codes below once bug 1320265 is resolved.
-    if (!article.dir && ["ar", "fa", "he", "ug", "ur"].includes(article.language)) {
-      article.dir = "rtl";
-    }
-  },
-
-  /**
-   * Assigns the estimated reading time range of the article to the article object.
-   *
-   * @param article the article object to assign the reading time estimate to.
-   */
-  _assignReadTime(article) {
-    let lang = article.language || "en";
-    const readingSpeed = this._getReadingSpeedForLanguage(lang);
-    const charactersPerMinuteLow = readingSpeed.cpm - readingSpeed.variance;
-    const charactersPerMinuteHigh = readingSpeed.cpm + readingSpeed.variance;
-    const length = article.length;
-
-    article.readingTimeMinsSlow = Math.ceil(length / charactersPerMinuteLow);
-    article.readingTimeMinsFast  = Math.ceil(length / charactersPerMinuteHigh);
-  },
-
-  /**
-   * Returns the reading speed of a selection of languages with likely variance.
-   *
-   * Reading speed estimated from a study done on reading speeds in various languages.
-   * study can be found here: http://iovs.arvojournals.org/article.aspx?articleid=2166061
-   *
-   * @return object with characters per minute and variance. Defaults to English
-   *         if no suitable language is found in the collection.
-   */
-  _getReadingSpeedForLanguage(lang) {
-    const readingSpeed = new Map([
-      [ "en", {cpm: 987,  variance: 118 } ],
-      [ "ar", {cpm: 612,  variance: 88 } ],
-      [ "de", {cpm: 920,  variance: 86 } ],
-      [ "es", {cpm: 1025, variance: 127 } ],
-      [ "fi", {cpm: 1078, variance: 121 } ],
-      [ "fr", {cpm: 998,  variance: 126 } ],
-      [ "he", {cpm: 833,  variance: 130 } ],
-      [ "it", {cpm: 950,  variance: 140 } ],
-      [ "jw", {cpm: 357,  variance: 56 } ],
-      [ "nl", {cpm: 978,  variance: 143 } ],
-      [ "pl", {cpm: 916,  variance: 126 } ],
-      [ "pt", {cpm: 913,  variance: 145 } ],
-      [ "ru", {cpm: 986,  variance: 175 } ],
-      [ "sk", {cpm: 885,  variance: 145 } ],
-      [ "sv", {cpm: 917,  variance: 156 } ],
-      [ "tr", {cpm: 1054, variance: 156 } ],
-      [ "zh", {cpm: 255,  variance: 29 } ],
-    ]);
-
-    return readingSpeed.get(lang) || readingSpeed.get("en");
-  },
-};
+XPCOMUtils.defineLazyPreferenceGetter(
+  Readerable, "isEnabled", "reader.parse-on-load.enabled", true);
+XPCOMUtils.defineLazyPreferenceGetter(
+  Readerable, "isForceEnabled", "reader.parse-on-load.force-enabled", false);
new file mode 100644
--- /dev/null
+++ b/toolkit/components/reader/Readerable.jsm
@@ -0,0 +1,10 @@
+// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Readerable"];
+
+#include Readability-readerable.js
+#include Readerable.js
--- a/toolkit/components/reader/moz.build
+++ b/toolkit/components/reader/moz.build
@@ -3,24 +3,28 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 JAR_MANIFESTS += ['jar.mn']
 
 EXTRA_JS_MODULES += [
   'AboutReader.jsm',
-  'ReaderMode.jsm'
+  'ReaderMode.jsm',
+]
+
+EXTRA_PP_JS_MODULES += [
+  'Readerable.jsm',
 ]
 
 EXTRA_JS_MODULES.reader = [
   'JSDOMParser.js',
   'Readability.js',
   'ReaderWorker.js',
-  'ReaderWorker.jsm'
+  'ReaderWorker.jsm',
 ]
 
 BROWSER_CHROME_MANIFESTS += [
   'test/browser.ini'
 ]
 
 with Files('**'):
     BUG_COMPONENT = ('Toolkit', 'Reader Mode')