The Tor Browser: mobile/android/chrome/content/Readability.js@fc2d59ddac77 (annotated)

mobile/android/chrome/content/Readability.js@fc2d59ddac77 (annotated)

mobile/android/chrome/content/Readability.js

Wed, 31 Dec 2014 07:22:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:22:50 +0100
branch: TOR_BUG_3246
changeset 4: fc2d59ddac77
permissions: -rw-r--r--

Correct previous dual key logic pending first delivery installment.

 /*
  * 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
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * 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
  */
 var Readability = function(uri, doc) {
   const ENABLE_LOGGING = false;
   this._uri = uri;
   this._doc = doc;
   this._biggestFrame = false;
   this._articleByline = null;
   this._articleDir = null;
   // Start with all flags set
   this._flags = this.FLAG_STRIP_UNLIKELYS |
                 this.FLAG_WEIGHT_CLASSES |
                 this.FLAG_CLEAN_CONDITIONALLY;
   // The list of pages we've parsed in this call of readability,
   // for autopaging. As a key store for easier searching.
   this._parsedPages = {};
   // A list of the ETag headers of pages we've parsed, in case they happen to match,
   // we'll know it's a duplicate.
   this._pageETags = {};
   // Make an AJAX request for each page and append it to the document.
   this._curPageNum = 1;
   // Control whether log messages are sent to the console
   if (ENABLE_LOGGING) {
     this.log = function (msg) {
       dump("Reader: (Readability) " + msg);
     };
   } else {
     this.log = function () {};
   }
 }
 Readability.prototype = {
   FLAG_STRIP_UNLIKELYS: 0x1,
   FLAG_WEIGHT_CLASSES: 0x2,
   FLAG_CLEAN_CONDITIONALLY: 0x4,
   // The number of top candidates to consider when analysing how
   // tight the competition is among candidates.
   N_TOP_CANDIDATES: 5,
   // The maximum number of pages to loop through before we call
   // it quits and just show a link.
   MAX_PAGES: 5,
   // All of the regular expressions in use within readability.
   // Defined up here so we don't instantiate them repeatedly in loops.
   REGEXPS: {
     unlikelyCandidates: /combx|comment|community|disqus|extra|foot|header|menu|remark|rss|shoutbox|sidebar|sponsor|ad-break|agegate|pagination|pager|popup|tweet|twitter/i,
     okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
     positive: /article|body|content|entry|hentry|main|page|pagination|post|text|blog|story/i,
     negative: /hidden|combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|shoutbox|sidebar|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/i,
     replaceFonts: /<(\/?)font[^>]*>/gi,
     trim: /^\s+|\s+$/g,
     normalize: /\s{2,}/g,
     videos: /http:\/\/(www\.)?(youtube|vimeo)\.com/i,
     nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
     prevLink: /(prev|earl|old|new|<|«)/i,
     whitespace: /^\s*$/
   },
   DIV_TO_P_ELEMS: [ "A", "BLOCKQUOTE", "DL", "DIV", "IMG", "OL", "P", "PRE", "TABLE", "UL", "SELECT" ],
   /**
    * 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);
   },
   /**
    * Converts each <a> and <img> uri in the given element to an absolute URI.
    *
    * @param Element
    * @return void
    */
   _fixRelativeUris: function(articleContent) {
     let scheme = this._uri.scheme;
     let prePath = this._uri.prePath;
     let pathBase = this._uri.pathBase;
     function toAbsoluteURI(uri) {
       // If this is already an absolute URI, return it.
       if (/^[a-zA-Z][a-zA-Z0-9\+\-\.]*:/.test(uri))
         return uri;
       // Scheme-rooted relative URI.
       if (uri.substr(0, 2) == "//")
         return scheme + "://" + uri.substr(2);
       // Prepath-rooted relative URI.
       if (uri[0] == "/")
         return prePath + uri;
       // Standard relative URI; add entire path. pathBase already includes a
       // trailing "/".
       return pathBase + uri;
     }
     function convertRelativeURIs(tagName, propName) {
       let elems = articleContent.getElementsByTagName(tagName);
       for (let i = elems.length; --i >= 0;) {
         let elem = elems[i];
         let relativeURI = elem.getAttribute(propName);
         if (relativeURI != null)
           elems[i].setAttribute(propName, toAbsoluteURI(relativeURI));
       }
     }
      // Fix links.
     convertRelativeURIs("a", "href");
      // Fix images.
     convertRelativeURIs("img", "src");
   },
   /**
    * Get the article title as an H1.
    *
    * @return void
    **/
   _getArticleTitle: function() {
     let doc = this._doc;
     let curTitle = "";
     let origTitle = "";
     try {
       curTitle = origTitle = doc.title;
       // 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) {}
     if (curTitle.match(/ [\|\-] /)) {
       curTitle = origTitle.replace(/(.*)[\|\-] .*/gi,'$1');
       if (curTitle.split(' ').length < 3)
         curTitle = origTitle.replace(/[^\|\-]*[\|\-](.*)/gi,'$1');
     } else if (curTitle.indexOf(': ') !== -1) {
       curTitle = origTitle.replace(/.*:(.*)/gi, '$1');
       if (curTitle.split(' ').length < 3)
         curTitle = origTitle.replace(/[^:]*[:](.*)/gi,'$1');
     } else if (curTitle.length > 150 || curTitle.length < 15) {
       let hOnes = doc.getElementsByTagName('h1');
       if (hOnes.length === 1)
         curTitle = this._getInnerText(hOnes[0]);
     }
     curTitle = curTitle.replace(this.REGEXPS.trim, "");
     if (curTitle.split(' ').length <= 4)
       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() {
     let doc = this._doc;
     // In some cases a body element can't be found (if the HTML is
     // totally hosed for example) so we create a new body node and
     // append it to the document.
     if (doc.body === null) {
       let body = doc.createElement("body");
       try {
         doc.body = body;
       } catch(e) {
         doc.documentElement.appendChild(body);
         this.log(e);
       }
     }
     // Remove all style tags in head
     let styleTags = doc.getElementsByTagName("style");
     for (let st = 0; st < styleTags.length; st += 1) {
       styleTags[st].textContent = "";
     }
     this._replaceBrs(doc.body);
     let fonts = doc.getElementsByTagName("FONT");
     for (let i = fonts.length; --i >=0;) {
       this._setNodeTag(fonts[i], "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) {
     let next = node;
     while (next
         && (next.nodeType != Node.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) {
     let brs = elem.getElementsByTagName("br");
     for (let i = 0; i < brs.length; i++) {
       let br = brs[i];
       let next = br.nextSibling;
       // Whether 2 or more <br> elements have been found and replaced with a
       // <p> block.
       let 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;
         let sibling = next.nextSibling;
         next.parentNode.removeChild(next);
         next = sibling;
       }
       // 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) {
         let 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") {
             let nextElem = this._nextElement(next);
             if (nextElem && nextElem.tagName == "BR")
               break;
           }
           // Otherwise, make this node a child of the new <p>.
           let sibling = next.nextSibling;
           p.appendChild(next);
           next = sibling;
         }
       }
     }
   },
   _setNodeTag: function (node, tag) {
     node.localName = tag.toLowerCase();
     node.tagName = tag.toUpperCase();
   },
   /**
    * 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);
     // Clean out junk from the article content
     this._cleanConditionally(articleContent, "form");
     this._clean(articleContent, "object");
     this._clean(articleContent, "h1");
     // If there is only one h2, they are probably using it as a header
     // and not a subheader, so remove it since we already have a header.
     if (articleContent.getElementsByTagName('h2').length === 1)
       this._clean(articleContent, "h2");
     this._clean(articleContent, "iframe");
     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
     let articleParagraphs = articleContent.getElementsByTagName('p');
     for (let i = articleParagraphs.length - 1; i >= 0; i -= 1) {
       let imgCount = articleParagraphs[i].getElementsByTagName('img').length;
       let embedCount = articleParagraphs[i].getElementsByTagName('embed').length;
       let objectCount = articleParagraphs[i].getElementsByTagName('object').length;
       if (imgCount === 0 &&
         embedCount === 0 &&
         objectCount === 0 &&
         this._getInnerText(articleParagraphs[i], false) === '')
         articleParagraphs[i].parentNode.removeChild(articleParagraphs[i]);
     }
     let brs = articleContent.getElementsByTagName("BR");
     for (let i = brs.length; --i >= 0;) {
       let br = brs[i];
       let next = this._nextElement(br.nextSibling);
       if (next && next.tagName == "P")
         br.parentNode.removeChild(br);
     }
   },
   /**
    * 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);
   },
   /***
    * 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) {
     let doc = this._doc;
     let isPaging = (page !== null ? true: false);
     page = page ? page : this._doc.body;
     let pageCacheHtml = page.innerHTML;
     // Check if any "dir" is set on the toplevel document element
     this._articleDir = doc.documentElement.getAttribute("dir");
     while (true) {
       let stripUnlikelyCandidates = this._flagIsActive(this.FLAG_STRIP_UNLIKELYS);
       let allElements = page.getElementsByTagName('*');
       // 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.)
       //
       // Note: Assignment from index for performance. See http://www.peachpit.com/articles/article.aspx?p=31567&seqNum=5
       // TODO: Shouldn't this be a reverse traversal?
       let node = null;
       let nodesToScore = [];
       // Let each node know its index in the allElements array.
       for (let i = allElements.length; --i >= 0;) {
         allElements[i]._index = i;
       }
       /**
        * JSDOMParser returns static node lists, not live ones. When we remove
        * an element from the document, we need to manually remove it - and all
        * of its children - from the allElements array.
        */
       function purgeNode(node) {
         for (let i = node.childNodes.length; --i >= 0;) {
           purgeNode(node.childNodes[i]);
         }
         if (node._index !== undefined && allElements[node._index] == node)
           delete allElements[node._index];
       }
       for (let nodeIndex = 0; nodeIndex < allElements.length; nodeIndex++) {
         if (!(node = allElements[nodeIndex]))
           continue;
         let matchString = node.className + node.id;
         if (matchString.search(this.REGEXPS.byline) !== -1 && !this._articleByline) {
           this._articleByline = node.textContent;
           node.parentNode.removeChild(node);
           purgeNode(node);
           continue;
         }
         // Remove unlikely candidates
         if (stripUnlikelyCandidates) {
           if (matchString.search(this.REGEXPS.unlikelyCandidates) !== -1 &&
             matchString.search(this.REGEXPS.okMaybeItsACandidate) === -1 &&
             node.tagName !== "BODY") {
             this.log("Removing unlikely candidate - " + matchString);
             node.parentNode.removeChild(node);
             purgeNode(node);
             continue;
           }
         }
         if (node.tagName === "P" || node.tagName === "TD" || node.tagName === "PRE")
           nodesToScore[nodesToScore.length] = node;
         // Turn all divs that don't have children block level elements into p's
         if (node.tagName === "DIV") {
           // 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.
           let pIndex = this._getSinglePIndexInsideDiv(node);
           if (pIndex >= 0 || !this._hasChildBlockElement(node)) {
             if (pIndex >= 0) {
               let newNode = node.childNodes[pIndex];
               node.parentNode.replaceChild(newNode, node);
               purgeNode(node);
             } else {
               this._setNodeTag(node, "P");
               nodesToScore[nodesToScore.length] = node;
             }
           } else {
             // EXPERIMENTAL
             for (let i = 0, il = node.childNodes.length; i < il; i += 1) {
               let childNode = node.childNodes[i];
               if (!childNode)
                 continue;
               if (childNode.nodeType === 3) { // Node.TEXT_NODE
                 let p = doc.createElement('p');
                 p.textContent = childNode.textContent;
                 p.style.display = 'inline';
                 p.className = 'readability-styled';
                 childNode.parentNode.replaceChild(p, childNode);
               }
             }
           }
         }
       }
       /**
        * 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.
       **/
       let candidates = [];
       for (let pt = 0; pt < nodesToScore.length; pt += 1) {
         let parentNode = nodesToScore[pt].parentNode;
         let grandParentNode = parentNode ? parentNode.parentNode : null;
         let innerText = this._getInnerText(nodesToScore[pt]);
         if (!parentNode || typeof(parentNode.tagName) === 'undefined')
           continue;
         // If this paragraph is less than 25 characters, don't even count it.
         if (innerText.length < 25)
           continue;
         // Initialize readability data for the parent.
         if (typeof parentNode.readability === 'undefined') {
           this._initializeNode(parentNode);
           candidates.push(parentNode);
         }
         // Initialize readability data for the grandparent.
         if (grandParentNode &&
           typeof(grandParentNode.readability) === 'undefined' &&
           typeof(grandParentNode.tagName) !== 'undefined') {
           this._initializeNode(grandParentNode);
           candidates.push(grandParentNode);
         }
         let 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);
         // Add the score to the parent. The grandparent gets half.
         parentNode.readability.contentScore += contentScore;
         if (grandParentNode)
           grandParentNode.readability.contentScore += contentScore / 2;
       }
       // After we've calculated scores, loop through all of the possible
       // candidate nodes we found and find the one with the highest score.
       let topCandidates = [];
       for (let c = 0, cl = candidates.length; c < cl; c += 1) {
         let 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.
         let candidateScore = candidate.readability.contentScore * (1 - this._getLinkDensity(candidate));
         candidate.readability.contentScore = candidateScore;
         this.log('Candidate: ' + candidate + " (" + candidate.className + ":" +
           candidate.id + ") with score " + candidateScore);
         for (let t = 0; t < this.N_TOP_CANDIDATES; t++) {
           let aTopCandidate = topCandidates[t];
           if (!aTopCandidate || candidateScore > aTopCandidate.readability.contentScore) {
             topCandidates.splice(t, 0, candidate);
             if (topCandidates.length > this.N_TOP_CANDIDATES)
               topCandidates.pop();
             break;
           }
         }
       }
       let topCandidate = topCandidates[0] || null;
       let lastTopCandidate = (topCandidates.length > 3 ? topCandidates[topCandidates.length - 1] : null);
       // 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");
         let children = page.childNodes;
         for (let i = 0; i < children.length; ++i) {
           topCandidate.appendChild(children[i]);
         }
         page.appendChild(topCandidate);
         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.
       let articleContent = doc.createElement("DIV");
       if (isPaging)
         articleContent.id = "readability-content";
       let siblingScoreThreshold = Math.max(10, topCandidate.readability.contentScore * 0.2);
       let siblingNodes = topCandidate.parentNode.childNodes;
       for (let s = 0, sl = siblingNodes.length; s < sl; s += 1) {
         let siblingNode = siblingNodes[s];
         let append = false;
         this.log("Looking at sibling node: " + siblingNode + " (" + siblingNode.className + ":" + siblingNode.id + ")" + ((typeof siblingNode.readability !== 'undefined') ? (" with score " + siblingNode.readability.contentScore) : ''));
         this.log("Sibling has score " + (siblingNode.readability ? siblingNode.readability.contentScore : 'Unknown'));
         if (siblingNode === topCandidate)
           append = true;
         let contentBonus = 0;
         // Give a bonus if sibling nodes and top candidates have the example same classname
         if (siblingNode.className === topCandidate.className && topCandidate.className !== "")
           contentBonus += topCandidate.readability.contentScore * 0.2;
         if (typeof siblingNode.readability !== 'undefined' &&
           (siblingNode.readability.contentScore+contentBonus) >= siblingScoreThreshold)
           append = true;
         if (siblingNode.nodeName === "P") {
           let linkDensity = this._getLinkDensity(siblingNode);
           let nodeContent = this._getInnerText(siblingNode);
           let nodeLength = nodeContent.length;
           if (nodeLength > 80 && linkDensity < 0.25) {
             append = true;
           } else if (nodeLength < 80 && linkDensity === 0 && nodeContent.search(/\.( |$)/) !== -1) {
             append = true;
           }
         }
         if (append) {
           this.log("Appending node: " + siblingNode);
           // siblingNodes is a reference to the childNodes array, and
           // siblingNode is removed from the array when we call appendChild()
           // below. As a result, we must revisit this index since the nodes
           // have been shifted.
           s -= 1;
           sl -= 1;
           if (siblingNode.nodeName !== "DIV" && siblingNode.nodeName !== "P") {
             // 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 siblingNode of " + siblingNode.nodeName + ' to div.');
             this._setNodeTag(siblingNode, "DIV");
           }
           // To ensure a node does not interfere with readability styles,
           // remove its classnames.
           siblingNode.className = "";
           // Append sibling and subtract from our list because it removes
           // the node when you append to another node.
           articleContent.appendChild(siblingNode);
         }
       }
       // So we have all of the content that we need. Now we clean it up for presentation.
       this._prepArticle(articleContent);
       if (this._curPageNum === 1) {
         let div = doc.createElement("DIV");
         div.id = "readability-page-1";
         div.className = "page";
         let children = articleContent.childNodes;
         for (let i = 0; i < children.length; ++i) {
           div.appendChild(children[i]);
         }
         articleContent.appendChild(div);
       }
       // 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.
       if (this._getInnerText(articleContent, true).length < 500) {
         page.innerHTML = pageCacheHtml;
         if (this._flagIsActive(this.FLAG_STRIP_UNLIKELYS)) {
           this._removeFlag(this.FLAG_STRIP_UNLIKELYS);
         } else if (this._flagIsActive(this.FLAG_WEIGHT_CLASSES)) {
           this._removeFlag(this.FLAG_WEIGHT_CLASSES);
         } else if (this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY)) {
           this._removeFlag(this.FLAG_CLEAN_CONDITIONALLY);
         } else {
           return null;
         }
       } else {
         if (lastTopCandidate !== null) {
           // EXPERIMENTAL: Contrast ratio is how we measure the level of competition between candidates in the
           // readability algorithm. This is to avoid offering reader mode on pages that are more like
           // a list or directory of links with summaries. It takes the score of the last top candidate
           // (see N_TOP_CANDIDATES) and checks how it compares to the top candidate's. On pages that are not
           // actual articles, there will likely be many candidates with similar score (i.e. higher contrast ratio).
           let contrastRatio = lastTopCandidate.readability.contentScore / topCandidate.readability.contentScore;
           if (contrastRatio > 0.45)
             return null;
         }
         return articleContent;
       }
     }
   },
   /**
    * Attempts to get the excerpt from these
    * sources in the following order:
    * - meta description tag
    * - open-graph description
    * - twitter cards description
    * - article's first paragraph
    * If no excerpt is found, an empty string will be
    * returned.
    *
    * @param Element - root element of the processed version page
    * @return String - excerpt of the article
   **/
   _getExcerpt: function(articleContent) {
     let values = {};
     let metaElements = this._doc.getElementsByTagName("meta");
     // Match "description", or Twitter's "twitter:description" (Cards)
     // in name attribute.
     let namePattern = /^\s*((twitter)\s*:\s*)?description\s*$/gi;
     // Match Facebook's og:description (Open Graph) in property attribute.
     let propertyPattern = /^\s*og\s*:\s*description\s*$/gi;
     // Find description tags.
     for (let i = 0; i < metaElements.length; i++) {
       let element = metaElements[i];
       let elementName = element.getAttribute("name");
       let elementProperty = element.getAttribute("property");
       let name;
       if (namePattern.test(elementName)) {
         name = elementName;
       } else if (propertyPattern.test(elementProperty)) {
         name = elementProperty;
       }
       if (name) {
         let content = element.getAttribute("content");
         if (content) {
           // Convert to lowercase and remove any whitespace
           // so we can match below.
           name = name.toLowerCase().replace(/\s/g, '');
           values[name] = content.trim();
         }
       }
     }
     if ("description" in values) {
       return values["description"];
     }
     if ("og:description" in values) {
       // Use facebook open graph description.
       return values["og:description"];
     }
     if ("twitter:description" in values) {
       // Use twitter cards description.
       return values["twitter:description"];
     }
     // No description meta tags, use the article's first paragraph.
     let paragraphs = articleContent.getElementsByTagName("p");
     if (paragraphs.length > 0) {
       return paragraphs[0].textContent;
     }
     return "";
   },
   /**
    * Removes script tags from the document.
    *
    * @param Element
   **/
   _removeScripts: function(doc) {
     let scripts = doc.getElementsByTagName('script');
     for (let i = scripts.length - 1; i >= 0; i -= 1) {
       scripts[i].nodeValue="";
       scripts[i].removeAttribute('src');
       if (scripts[i].parentNode)
           scripts[i].parentNode.removeChild(scripts[i]);
     }
   },
   /**
    * Get child index of the only P element inside a DIV with no
    * text content. Returns -1 if the DIV node contains non-empty
    * text nodes or if it contains other element nodes.
    *
    * @param Element
   **/
   _getSinglePIndexInsideDiv: function(e) {
     let childNodes = e.childNodes;
     let pIndex = -1;
     for (let i = childNodes.length; --i >= 0;) {
       let node = childNodes[i];
       if (node.nodeType === Node.ELEMENT_NODE) {
         if (node.tagName !== "P")
           return -1;
         if (pIndex >= 0)
           return -1;
         pIndex = i;
       } else if (node.nodeType == Node.TEXT_NODE && this._getInnerText(node, false)) {
         return -1;
       }
     }
     return pIndex;
   },
   /**
    * Determine whether element has any children block level elements.
    *
    * @param Element
    */
   _hasChildBlockElement: function (e) {
     let length = e.childNodes.length;
     for (let i = 0; i < length; i++) {
       let child = e.childNodes[i];
       if (child.nodeType != 1)
         continue;
       if (this.DIV_TO_P_ELEMS.indexOf(child.tagName) !== -1 || this._hasChildBlockElement(child))
         return true;
     }
     return false;
   },
   /**
    * Get the inner text of a node - cross browser compatibly.
    * This also strips out any excess whitespace to be found.
    *
    * @param Element
    * @return string
   **/
   _getInnerText: function(e, normalizeSpaces) {
     let textContent = e.textContent.replace(this.REGEXPS.trim, "");
     normalizeSpaces = (typeof normalizeSpaces === 'undefined') ? true : normalizeSpaces;
     if (normalizeSpaces) {
       return textContent.replace(this.REGEXPS.normalize, " ");
     } else {
       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) {
     e = e || this._doc;
     let cur = e.firstChild;
     if (!e)
       return;
     // Remove any root styles, if we're able.
     if (typeof e.removeAttribute === 'function' && e.className !== 'readability-styled')
       e.removeAttribute('style');
     // Go until there are no more child nodes
     while (cur !== null) {
       if (cur.nodeType === 1) {
         // Remove style attribute(s) :
         if (cur.className !== "readability-styled")
           cur.removeAttribute("style");
         this._cleanStyles(cur);
       }
       cur = cur.nextSibling;
     }
   },
   /**
    * 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(e) {
     let links = e.getElementsByTagName("a");
     let textLength = this._getInnerText(e).length;
     let linkLength = 0;
     for (let i = 0, il = links.length; i < il; i += 1) {
       linkLength += this._getInnerText(links[i]).length;
     }
     return linkLength / textLength;
   },
   /**
    * Find a cleaned up version of the current URL, to use for comparing links for possible next-pageyness.
    *
    * @author Dan Lacy
    * @return string the base url
   **/
   _findBaseUrl: function() {
     let uri = this._uri;
     let noUrlParams = uri.path.split("?")[0];
     let urlSlashes = noUrlParams.split("/").reverse();
     let cleanedSegments = [];
     let possibleType = "";
     for (let i = 0, slashLen = urlSlashes.length; i < slashLen; i += 1) {
       let segment = urlSlashes[i];
       // Split off and save anything that looks like a file type.
       if (segment.indexOf(".") !== -1) {
         possibleType = segment.split(".")[1];
         // If the type isn't alpha-only, it's probably not actually a file extension.
         if (!possibleType.match(/[^a-zA-Z]/))
           segment = segment.split(".")[0];
       }
       // EW-CMS specific segment replacement. Ugly.
       // Example: http://www.ew.com/ew/article/0,,20313460_20369436,00.html
       if (segment.indexOf(',00') !== -1)
         segment = segment.replace(',00', '');
       // If our first or second segment has anything looking like a page number, remove it.
       if (segment.match(/((_|-)?p[a-z]*|(_|-))[0-9]{1,2}$/i) && ((i === 1) || (i === 0)))
         segment = segment.replace(/((_|-)?p[a-z]*|(_|-))[0-9]{1,2}$/i, "");
       let del = false;
       // If this is purely a number, and it's the first or second segment,
       // it's probably a page number. Remove it.
       if (i < 2 && segment.match(/^\d{1,2}$/))
         del = true;
       // If this is the first segment and it's just "index", remove it.
       if (i === 0 && segment.toLowerCase() === "index")
         del = true;
       // If our first or second segment is smaller than 3 characters,
       // and the first segment was purely alphas, remove it.
       if (i < 2 && segment.length < 3 && !urlSlashes[0].match(/[a-z]/i))
         del = true;
       // If it's not marked for deletion, push it to cleanedSegments.
       if (!del)
         cleanedSegments.push(segment);
     }
     // This is our final, cleaned, base article URL.
     return uri.scheme + "://" + uri.host + cleanedSegments.reverse().join("/");
   },
   /**
    * Look for any paging links that may occur within the document.
    *
    * @param body
    * @return object (array)
   **/
   _findNextPageLink: function(elem) {
     let uri = this._uri;
     let possiblePages = {};
     let allLinks = elem.getElementsByTagName('a');
     let articleBaseUrl = this._findBaseUrl();
     // Loop through all links, looking for hints that they may be next-page links.
     // Things like having "page" in their textContent, className or id, or being a child
     // of a node with a page-y className or id.
     //
     // Also possible: levenshtein distance? longest common subsequence?
     //
     // After we do that, assign each page a score, and
     for (let i = 0, il = allLinks.length; i < il; i += 1) {
       let link = allLinks[i];
       let linkHref = allLinks[i].href.replace(/#.*$/, '').replace(/\/$/, '');
       // If we've already seen this page, ignore it.
       if (linkHref === "" ||
         linkHref === articleBaseUrl ||
         linkHref === uri.spec ||
         linkHref in this._parsedPages) {
         continue;
       }
       // If it's on a different domain, skip it.
       if (uri.host !== linkHref.split(/\/+/g)[1])
         continue;
       let linkText = this._getInnerText(link);
       // If the linkText looks like it's not the next page, skip it.
       if (linkText.match(this.REGEXPS.extraneous) || linkText.length > 25)
         continue;
       // If the leftovers of the URL after removing the base URL don't contain
       // any digits, it's certainly not a next page link.
       let linkHrefLeftover = linkHref.replace(articleBaseUrl, '');
       if (!linkHrefLeftover.match(/\d/))
         continue;
       if (!(linkHref in possiblePages)) {
         possiblePages[linkHref] = {"score": 0, "linkText": linkText, "href": linkHref};
       } else {
         possiblePages[linkHref].linkText += ' | ' + linkText;
       }
       let linkObj = possiblePages[linkHref];
       // If the articleBaseUrl isn't part of this URL, penalize this link. It could
       // still be the link, but the odds are lower.
       // Example: http://www.actionscript.org/resources/articles/745/1/JavaScript-and-VBScript-Injection-in-ActionScript-3/Page1.html
       if (linkHref.indexOf(articleBaseUrl) !== 0)
         linkObj.score -= 25;
       let linkData = linkText + ' ' + link.className + ' ' + link.id;
       if (linkData.match(this.REGEXPS.nextLink))
         linkObj.score += 50;
       if (linkData.match(/pag(e|ing|inat)/i))
         linkObj.score += 25;
       if (linkData.match(/(first|last)/i)) {
         // -65 is enough to negate any bonuses gotten from a > or » in the text,
         // If we already matched on "next", last is probably fine.
         // If we didn't, then it's bad. Penalize.
         if (!linkObj.linkText.match(this.REGEXPS.nextLink))
           linkObj.score -= 65;
       }
       if (linkData.match(this.REGEXPS.negative) || linkData.match(this.REGEXPS.extraneous))
         linkObj.score -= 50;
       if (linkData.match(this.REGEXPS.prevLink))
         linkObj.score -= 200;
       // If a parentNode contains page or paging or paginat
       let parentNode = link.parentNode;
       let positiveNodeMatch = false;
       let negativeNodeMatch = false;
       while (parentNode) {
         let parentNodeClassAndId = parentNode.className + ' ' + parentNode.id;
         if (!positiveNodeMatch && parentNodeClassAndId && parentNodeClassAndId.match(/pag(e|ing|inat)/i)) {
           positiveNodeMatch = true;
           linkObj.score += 25;
         }
         if (!negativeNodeMatch && parentNodeClassAndId && parentNodeClassAndId.match(this.REGEXPS.negative)) {
           // If this is just something like "footer", give it a negative.
           // If it's something like "body-and-footer", leave it be.
           if (!parentNodeClassAndId.match(this.REGEXPS.positive)) {
             linkObj.score -= 25;
             negativeNodeMatch = true;
           }
         }
         parentNode = parentNode.parentNode;
       }
       // If the URL looks like it has paging in it, add to the score.
       // Things like /page/2/, /pagenum/2, ?p=3, ?page=11, ?pagination=34
       if (linkHref.match(/p(a|g|ag)?(e|ing|ination)?(=|\/)[0-9]{1,2}/i) || linkHref.match(/(page|paging)/i))
         linkObj.score += 25;
       // If the URL contains negative values, give a slight decrease.
       if (linkHref.match(this.REGEXPS.extraneous))
         linkObj.score -= 15;
       /**
        * Minor punishment to anything that doesn't match our current URL.
        * NOTE: I'm finding this to cause more harm than good where something is exactly 50 points.
        *     Dan, can you show me a counterexample where this is necessary?
        * if (linkHref.indexOf(window.location.href) !== 0) {
        *  linkObj.score -= 1;
        * }
       **/
       // If the link text can be parsed as a number, give it a minor bonus, with a slight
       // bias towards lower numbered pages. This is so that pages that might not have 'next'
       // in their text can still get scored, and sorted properly by score.
       let linkTextAsNumber = parseInt(linkText, 10);
       if (linkTextAsNumber) {
         // Punish 1 since we're either already there, or it's probably
         // before what we want anyways.
         if (linkTextAsNumber === 1) {
           linkObj.score -= 10;
         } else {
           linkObj.score += Math.max(0, 10 - linkTextAsNumber);
         }
       }
     }
     // Loop thrugh all of our possible pages from above and find our top
     // candidate for the next page URL. Require at least a score of 50, which
     // is a relatively high confidence that this page is the next link.
     let topPage = null;
     for (let page in possiblePages) {
       if (possiblePages.hasOwnProperty(page)) {
         if (possiblePages[page].score >= 50 &&
           (!topPage || topPage.score < possiblePages[page].score))
           topPage = possiblePages[page];
       }
     }
     if (topPage) {
       let nextHref = topPage.href.replace(/\/$/,'');
       this.log('NEXT PAGE IS ' + nextHref);
       this._parsedPages[nextHref] = true;
       return nextHref;
     } else {
       return null;
     }
   },
   _successfulRequest: function(request) {
     return (request.status >= 200 && request.status < 300) ||
         request.status === 304 ||
          (request.status === 0 && request.responseText);
   },
   _ajax: function(url, options) {
     let request = new XMLHttpRequest();
     function respondToReadyState(readyState) {
       if (request.readyState === 4) {
         if (this._successfulRequest(request)) {
           if (options.success)
             options.success(request);
         } else {
           if (options.error)
             options.error(request);
         }
       }
     }
     if (typeof options === 'undefined')
       options = {};
     request.onreadystatechange = respondToReadyState;
     request.open('get', url, true);
     request.setRequestHeader('Accept', 'text/html');
     try {
       request.send(options.postBody);
     } catch (e) {
       if (options.error)
         options.error();
     }
     return request;
   },
   _appendNextPage: function(nextPageLink) {
     let doc = this._doc;
     this._curPageNum += 1;
     let articlePage = doc.createElement("DIV");
     articlePage.id = 'readability-page-' + this._curPageNum;
     articlePage.className = 'page';
     articlePage.innerHTML = '<p class="page-separator" title="Page ' + this._curPageNum + '">&sect;</p>';
     doc.getElementById("readability-content").appendChild(articlePage);
     if (this._curPageNum > this.MAX_PAGES) {
       let nextPageMarkup = "<div style='text-align: center'><a href='" + nextPageLink + "'>View Next Page</a></div>";
       articlePage.innerHTML = articlePage.innerHTML + nextPageMarkup;
       return;
     }
     // Now that we've built the article page DOM element, get the page content
     // asynchronously and load the cleaned content into the div we created for it.
     (function(pageUrl, thisPage) {
       this._ajax(pageUrl, {
         success: function(r) {
           // First, check to see if we have a matching ETag in headers - if we do, this is a duplicate page.
           let eTag = r.getResponseHeader('ETag');
           if (eTag) {
             if (eTag in this._pageETags) {
               this.log("Exact duplicate page found via ETag. Aborting.");
               articlePage.style.display = 'none';
               return;
             } else {
               this._pageETags[eTag] = 1;
             }
           }
           // TODO: this ends up doubling up page numbers on NYTimes articles. Need to generically parse those away.
           let page = doc.createElement("DIV");
           // Do some preprocessing to our HTML to make it ready for appending.
           // - Remove any script tags. Swap and reswap newlines with a unicode
           //   character because multiline regex doesn't work in javascript.
           // - Turn any noscript tags into divs so that we can parse them. This
           //   allows us to find any next page links hidden via javascript.
           // - Turn all double br's into p's - was handled by prepDocument in the original view.
           //   Maybe in the future abstract out prepDocument to work for both the original document
           //   and AJAX-added pages.
           let responseHtml = r.responseText.replace(/\n/g,'\uffff').replace(/<script.*?>.*?<\/script>/gi, '');
           responseHtml = responseHtml.replace(/\n/g,'\uffff').replace(/<script.*?>.*?<\/script>/gi, '');
           responseHtml = responseHtml.replace(/\uffff/g,'\n').replace(/<(\/?)noscript/gi, '<$1div');
           responseHtml = responseHtml.replace(this.REGEXPS.replaceFonts, '<$1span>');
           page.innerHTML = responseHtml;
           this._replaceBrs(page);
           // Reset all flags for the next page, as they will search through it and
           // disable as necessary at the end of grabArticle.
           this._flags = 0x1 | 0x2 | 0x4;
           let nextPageLink = this._findNextPageLink(page);
           // NOTE: if we end up supporting _appendNextPage(), we'll need to
           // change this call to be async
           let content = this._grabArticle(page);
           if (!content) {
             this.log("No content found in page to append. Aborting.");
             return;
           }
           // Anti-duplicate mechanism. Essentially, get the first paragraph of our new page.
           // Compare it against all of the the previous document's we've gotten. If the previous
           // document contains exactly the innerHTML of this first paragraph, it's probably a duplicate.
           let firstP = content.getElementsByTagName("P").length ? content.getElementsByTagName("P")[0] : null;
           if (firstP && firstP.innerHTML.length > 100) {
             for (let i = 1; i <= this._curPageNum; i += 1) {
               let rPage = doc.getElementById('readability-page-' + i);
               if (rPage && rPage.innerHTML.indexOf(firstP.innerHTML) !== -1) {
                 this.log('Duplicate of page ' + i + ' - skipping.');
                 articlePage.style.display = 'none';
                 this._parsedPages[pageUrl] = true;
                 return;
               }
             }
           }
           this._removeScripts(content);
           thisPage.innerHTML = thisPage.innerHTML + content.innerHTML;
           // After the page has rendered, post process the content. This delay is necessary because,
           // in webkit at least, offsetWidth is not set in time to determine image width. We have to
           // wait a little bit for reflow to finish before we can fix floating images.
           setTimeout((function() {
             this._postProcessContent(thisPage);
           }).bind(this), 500);
           if (nextPageLink)
             this._appendNextPage(nextPageLink);
         }
       });
     }).bind(this)(nextPageLink, articlePage);
   },
   /**
    * 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;
     let weight = 0;
     // Look for a special classname
     if (typeof(e.className) === 'string' && e.className !== '') {
       if (e.className.search(this.REGEXPS.negative) !== -1)
         weight -= 25;
       if (e.className.search(this.REGEXPS.positive) !== -1)
         weight += 25;
     }
     // Look for a special ID
     if (typeof(e.id) === 'string' && e.id !== '') {
       if (e.id.search(this.REGEXPS.negative) !== -1)
         weight -= 25;
       if (e.id.search(this.REGEXPS.positive) !== -1)
         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) {
     let targetList = e.getElementsByTagName(tag);
     let isEmbed = (tag === 'object' || tag === 'embed');
     for (let y = targetList.length - 1; y >= 0; y -= 1) {
       // Allow youtube and vimeo videos through as people usually want to see those.
       if (isEmbed) {
         let attributeValues = "";
         for (let i = 0, il = targetList[y].attributes.length; i < il; i += 1) {
           attributeValues += targetList[y].attributes[i].value + '|';
         }
         // First, check the elements attributes to see if any of them contain youtube or vimeo
         if (attributeValues.search(this.REGEXPS.videos) !== -1)
           continue;
         // Then check the elements inside this element for the same.
         if (targetList[y].innerHTML.search(this.REGEXPS.videos) !== -1)
           continue;
       }
       targetList[y].parentNode.removeChild(targetList[y]);
     }
   },
   /**
    * 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;
     let tagsList = e.getElementsByTagName(tag);
     let curTagsLength = tagsList.length;
     // 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.
     for (let i = curTagsLength-1; i >= 0; i -= 1) {
       let weight = this._getClassWeight(tagsList[i]);
       let contentScore = 0;
       this.log("Cleaning Conditionally " + tagsList[i] + " (" + tagsList[i].className + ":" + tagsList[i].id + ")");
       if (weight + contentScore < 0) {
         tagsList[i].parentNode.removeChild(tagsList[i]);
       } else if (this._getCharCount(tagsList[i],',') < 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.
         let p = tagsList[i].getElementsByTagName("p").length;
         let img = tagsList[i].getElementsByTagName("img").length;
         let li = tagsList[i].getElementsByTagName("li").length-100;
         let input = tagsList[i].getElementsByTagName("input").length;
         let embedCount = 0;
         let embeds = tagsList[i].getElementsByTagName("embed");
         for (let ei = 0, il = embeds.length; ei < il; ei += 1) {
           if (embeds[ei].src.search(this.REGEXPS.videos) === -1)
             embedCount += 1;
         }
         let linkDensity = this._getLinkDensity(tagsList[i]);
         let contentLength = this._getInnerText(tagsList[i]).length;
         let toRemove = false;
         if (img > p) {
           toRemove = true;
         } else if (li > p && tag !== "ul" && tag !== "ol") {
           toRemove = true;
         } else if ( input > Math.floor(p/3) ) {
           toRemove = true;
         } else if (contentLength < 25 && (img === 0 || img > 2) ) {
           toRemove = true;
         } else if (weight < 25 && linkDensity > 0.2) {
           toRemove = true;
         } else if (weight >= 25 && linkDensity > 0.5) {
           toRemove = true;
         } else if ((embedCount === 1 && contentLength < 75) || embedCount > 1) {
           toRemove = true;
         }
         if (toRemove)
           tagsList[i].parentNode.removeChild(tagsList[i]);
       }
     }
   },
   /**
    * Clean out spurious headers from an Element. Checks things like classnames and link density.
    *
    * @param Element
    * @return void
   **/
   _cleanHeaders: function(e) {
     for (let headerIndex = 1; headerIndex < 3; headerIndex += 1) {
       let headers = e.getElementsByTagName('h' + headerIndex);
       for (let i = headers.length - 1; i >= 0; i -= 1) {
         if (this._getClassWeight(headers[i]) < 0 || this._getLinkDensity(headers[i]) > 0.33)
           headers[i].parentNode.removeChild(headers[i]);
       }
     }
   },
   _flagIsActive: function(flag) {
     return (this._flags & flag) > 0;
   },
   _addFlag: function(flag) {
     this._flags = this._flags | flag;
   },
   _removeFlag: function(flag) {
     this._flags = this._flags & ~flag;
   },
   /**
    * 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 () {
     // Remove script tags from the document.
     this._removeScripts(this._doc);
     // FIXME: Disabled multi-page article support for now as it
     // needs more work on infrastructure.
     // Make sure this document is added to the list of parsed pages first,
     // so we don't double up on the first page.
     // this._parsedPages[uri.spec.replace(/\/$/, '')] = true;
     // Pull out any possible next page link first.
     // let nextPageLink = this._findNextPageLink(doc.body);
     this._prepDocument();
     let articleTitle = this._getArticleTitle();
     let articleContent = this._grabArticle();
     if (!articleContent)
       return null;
     this._postProcessContent(articleContent);
     // if (nextPageLink) {
     //   // Append any additional pages after a small timeout so that people
     //   // can start reading without having to wait for this to finish processing.
     //   setTimeout((function() {
     //     this._appendNextPage(nextPageLink);
     //   }).bind(this), 500);
     // }
     let excerpt = this._getExcerpt(articleContent);
     return { title: articleTitle,
              byline: this._articleByline,
              dir: this._articleDir,
              content: articleContent.innerHTML,
              length: articleContent.textContent.length,
              excerpt: excerpt };
   }
 };