Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 3632 insertions, 0 deletions

diff --git a/toolkit/components/reader/readability/JSDOMParser.js b/toolkit/components/reader/readability/JSDOMParser.js
new file mode 100644
index 0000000000..7b6d241b43
--- /dev/null
+++ b/toolkit/components/reader/readability/JSDOMParser.js
@@ -0,0 +1,1197 @@
+/* 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/. */
+
+/**
+ * This is a relatively lightweight DOMParser that is safe to use in a web
+ * worker. This is far from a complete DOM implementation; however, it should
+ * contain the minimal set of functionality necessary for Readability.js.
+ *
+ * Aside from not implementing the full DOM API, there are other quirks to be
+ * aware of when using the JSDOMParser:
+ *
+ *   1) Properly formed HTML/XML must be used. This means you should be extra
+ *      careful when using this parser on anything received directly from an
+ *      XMLHttpRequest. Providing a serialized string from an XMLSerializer,
+ *      however, should be safe (since the browser's XMLSerializer should
+ *      generate valid HTML/XML). Therefore, if parsing a document from an XHR,
+ *      the recommended approach is to do the XHR in the main thread, use
+ *      XMLSerializer.serializeToString() on the responseXML, and pass the
+ *      resulting string to the worker.
+ *
+ *   2) Live NodeLists are not supported. DOM methods and properties such as
+ *      getElementsByTagName() and childNodes return standard arrays. If you
+ *      want these lists to be updated when nodes are removed or added to the
+ *      document, you must take care to manually update them yourself.
+ */
+(function (global) {
+
+  // XML only defines these and the numeric ones:
+
+  var entityTable = {
+    "lt": "<",
+    "gt": ">",
+    "amp": "&",
+    "quot": '"',
+    "apos": "'",
+  };
+
+  var reverseEntityTable = {
+    "<": "&lt;",
+    ">": "&gt;",
+    "&": "&amp;",
+    '"': "&quot;",
+    "'": "&apos;",
+  };
+
+  function encodeTextContentHTML(s) {
+    return s.replace(/[&<>]/g, function(x) {
+      return reverseEntityTable[x];
+    });
+  }
+
+  function encodeHTML(s) {
+    return s.replace(/[&<>'"]/g, function(x) {
+      return reverseEntityTable[x];
+    });
+  }
+
+  function decodeHTML(str) {
+    return str.replace(/&(quot|amp|apos|lt|gt);/g, function(match, tag) {
+      return entityTable[tag];
+    }).replace(/&#(?:x([0-9a-z]{1,4})|([0-9]{1,4}));/gi, function(match, hex, numStr) {
+      var num = parseInt(hex || numStr, hex ? 16 : 10); // read num
+      return String.fromCharCode(num);
+    });
+  }
+
+  // When a style is set in JS, map it to the corresponding CSS attribute
+  var styleMap = {
+    "alignmentBaseline": "alignment-baseline",
+    "background": "background",
+    "backgroundAttachment": "background-attachment",
+    "backgroundClip": "background-clip",
+    "backgroundColor": "background-color",
+    "backgroundImage": "background-image",
+    "backgroundOrigin": "background-origin",
+    "backgroundPosition": "background-position",
+    "backgroundPositionX": "background-position-x",
+    "backgroundPositionY": "background-position-y",
+    "backgroundRepeat": "background-repeat",
+    "backgroundRepeatX": "background-repeat-x",
+    "backgroundRepeatY": "background-repeat-y",
+    "backgroundSize": "background-size",
+    "baselineShift": "baseline-shift",
+    "border": "border",
+    "borderBottom": "border-bottom",
+    "borderBottomColor": "border-bottom-color",
+    "borderBottomLeftRadius": "border-bottom-left-radius",
+    "borderBottomRightRadius": "border-bottom-right-radius",
+    "borderBottomStyle": "border-bottom-style",
+    "borderBottomWidth": "border-bottom-width",
+    "borderCollapse": "border-collapse",
+    "borderColor": "border-color",
+    "borderImage": "border-image",
+    "borderImageOutset": "border-image-outset",
+    "borderImageRepeat": "border-image-repeat",
+    "borderImageSlice": "border-image-slice",
+    "borderImageSource": "border-image-source",
+    "borderImageWidth": "border-image-width",
+    "borderLeft": "border-left",
+    "borderLeftColor": "border-left-color",
+    "borderLeftStyle": "border-left-style",
+    "borderLeftWidth": "border-left-width",
+    "borderRadius": "border-radius",
+    "borderRight": "border-right",
+    "borderRightColor": "border-right-color",
+    "borderRightStyle": "border-right-style",
+    "borderRightWidth": "border-right-width",
+    "borderSpacing": "border-spacing",
+    "borderStyle": "border-style",
+    "borderTop": "border-top",
+    "borderTopColor": "border-top-color",
+    "borderTopLeftRadius": "border-top-left-radius",
+    "borderTopRightRadius": "border-top-right-radius",
+    "borderTopStyle": "border-top-style",
+    "borderTopWidth": "border-top-width",
+    "borderWidth": "border-width",
+    "bottom": "bottom",
+    "boxShadow": "box-shadow",
+    "boxSizing": "box-sizing",
+    "captionSide": "caption-side",
+    "clear": "clear",
+    "clip": "clip",
+    "clipPath": "clip-path",
+    "clipRule": "clip-rule",
+    "color": "color",
+    "colorInterpolation": "color-interpolation",
+    "colorInterpolationFilters": "color-interpolation-filters",
+    "colorProfile": "color-profile",
+    "colorRendering": "color-rendering",
+    "content": "content",
+    "counterIncrement": "counter-increment",
+    "counterReset": "counter-reset",
+    "cursor": "cursor",
+    "direction": "direction",
+    "display": "display",
+    "dominantBaseline": "dominant-baseline",
+    "emptyCells": "empty-cells",
+    "enableBackground": "enable-background",
+    "fill": "fill",
+    "fillOpacity": "fill-opacity",
+    "fillRule": "fill-rule",
+    "filter": "filter",
+    "cssFloat": "float",
+    "floodColor": "flood-color",
+    "floodOpacity": "flood-opacity",
+    "font": "font",
+    "fontFamily": "font-family",
+    "fontSize": "font-size",
+    "fontStretch": "font-stretch",
+    "fontStyle": "font-style",
+    "fontVariant": "font-variant",
+    "fontWeight": "font-weight",
+    "glyphOrientationHorizontal": "glyph-orientation-horizontal",
+    "glyphOrientationVertical": "glyph-orientation-vertical",
+    "height": "height",
+    "imageRendering": "image-rendering",
+    "kerning": "kerning",
+    "left": "left",
+    "letterSpacing": "letter-spacing",
+    "lightingColor": "lighting-color",
+    "lineHeight": "line-height",
+    "listStyle": "list-style",
+    "listStyleImage": "list-style-image",
+    "listStylePosition": "list-style-position",
+    "listStyleType": "list-style-type",
+    "margin": "margin",
+    "marginBottom": "margin-bottom",
+    "marginLeft": "margin-left",
+    "marginRight": "margin-right",
+    "marginTop": "margin-top",
+    "marker": "marker",
+    "markerEnd": "marker-end",
+    "markerMid": "marker-mid",
+    "markerStart": "marker-start",
+    "mask": "mask",
+    "maxHeight": "max-height",
+    "maxWidth": "max-width",
+    "minHeight": "min-height",
+    "minWidth": "min-width",
+    "opacity": "opacity",
+    "orphans": "orphans",
+    "outline": "outline",
+    "outlineColor": "outline-color",
+    "outlineOffset": "outline-offset",
+    "outlineStyle": "outline-style",
+    "outlineWidth": "outline-width",
+    "overflow": "overflow",
+    "overflowX": "overflow-x",
+    "overflowY": "overflow-y",
+    "padding": "padding",
+    "paddingBottom": "padding-bottom",
+    "paddingLeft": "padding-left",
+    "paddingRight": "padding-right",
+    "paddingTop": "padding-top",
+    "page": "page",
+    "pageBreakAfter": "page-break-after",
+    "pageBreakBefore": "page-break-before",
+    "pageBreakInside": "page-break-inside",
+    "pointerEvents": "pointer-events",
+    "position": "position",
+    "quotes": "quotes",
+    "resize": "resize",
+    "right": "right",
+    "shapeRendering": "shape-rendering",
+    "size": "size",
+    "speak": "speak",
+    "src": "src",
+    "stopColor": "stop-color",
+    "stopOpacity": "stop-opacity",
+    "stroke": "stroke",
+    "strokeDasharray": "stroke-dasharray",
+    "strokeDashoffset": "stroke-dashoffset",
+    "strokeLinecap": "stroke-linecap",
+    "strokeLinejoin": "stroke-linejoin",
+    "strokeMiterlimit": "stroke-miterlimit",
+    "strokeOpacity": "stroke-opacity",
+    "strokeWidth": "stroke-width",
+    "tableLayout": "table-layout",
+    "textAlign": "text-align",
+    "textAnchor": "text-anchor",
+    "textDecoration": "text-decoration",
+    "textIndent": "text-indent",
+    "textLineThrough": "text-line-through",
+    "textLineThroughColor": "text-line-through-color",
+    "textLineThroughMode": "text-line-through-mode",
+    "textLineThroughStyle": "text-line-through-style",
+    "textLineThroughWidth": "text-line-through-width",
+    "textOverflow": "text-overflow",
+    "textOverline": "text-overline",
+    "textOverlineColor": "text-overline-color",
+    "textOverlineMode": "text-overline-mode",
+    "textOverlineStyle": "text-overline-style",
+    "textOverlineWidth": "text-overline-width",
+    "textRendering": "text-rendering",
+    "textShadow": "text-shadow",
+    "textTransform": "text-transform",
+    "textUnderline": "text-underline",
+    "textUnderlineColor": "text-underline-color",
+    "textUnderlineMode": "text-underline-mode",
+    "textUnderlineStyle": "text-underline-style",
+    "textUnderlineWidth": "text-underline-width",
+    "top": "top",
+    "unicodeBidi": "unicode-bidi",
+    "unicodeRange": "unicode-range",
+    "vectorEffect": "vector-effect",
+    "verticalAlign": "vertical-align",
+    "visibility": "visibility",
+    "whiteSpace": "white-space",
+    "widows": "widows",
+    "width": "width",
+    "wordBreak": "word-break",
+    "wordSpacing": "word-spacing",
+    "wordWrap": "word-wrap",
+    "writingMode": "writing-mode",
+    "zIndex": "z-index",
+    "zoom": "zoom",
+  };
+
+  // Elements that can be self-closing
+  var voidElems = {
+    "area": true,
+    "base": true,
+    "br": true,
+    "col": true,
+    "command": true,
+    "embed": true,
+    "hr": true,
+    "img": true,
+    "input": true,
+    "link": true,
+    "meta": true,
+    "param": true,
+    "source": true,
+    "wbr": true
+  };
+
+  var whitespace = [" ", "\t", "\n", "\r"];
+
+  // See https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType
+  var nodeTypes = {
+    ELEMENT_NODE: 1,
+    ATTRIBUTE_NODE: 2,
+    TEXT_NODE: 3,
+    CDATA_SECTION_NODE: 4,
+    ENTITY_REFERENCE_NODE: 5,
+    ENTITY_NODE: 6,
+    PROCESSING_INSTRUCTION_NODE: 7,
+    COMMENT_NODE: 8,
+    DOCUMENT_NODE: 9,
+    DOCUMENT_TYPE_NODE: 10,
+    DOCUMENT_FRAGMENT_NODE: 11,
+    NOTATION_NODE: 12
+  };
+
+  function getElementsByTagName(tag) {
+    tag = tag.toUpperCase();
+    var elems = [];
+    var allTags = (tag === "*");
+    function getElems(node) {
+      var length = node.children.length;
+      for (var i = 0; i < length; i++) {
+        var child = node.children[i];
+        if (allTags || (child.tagName === tag))
+          elems.push(child);
+        getElems(child);
+      }
+    }
+    getElems(this);
+    elems._isLiveNodeList = true;
+    return elems;
+  }
+
+  var Node = function () {};
+
+  Node.prototype = {
+    attributes: null,
+    childNodes: null,
+    localName: null,
+    nodeName: null,
+    parentNode: null,
+    textContent: null,
+    nextSibling: null,
+    previousSibling: null,
+
+    get firstChild() {
+      return this.childNodes[0] || null;
+    },
+
+    get firstElementChild() {
+      return this.children[0] || null;
+    },
+
+    get lastChild() {
+      return this.childNodes[this.childNodes.length - 1] || null;
+    },
+
+    get lastElementChild() {
+      return this.children[this.children.length - 1] || null;
+    },
+
+    appendChild: function (child) {
+      if (child.parentNode) {
+        child.parentNode.removeChild(child);
+      }
+
+      var last = this.lastChild;
+      if (last)
+        last.nextSibling = child;
+      child.previousSibling = last;
+
+      if (child.nodeType === Node.ELEMENT_NODE) {
+        child.previousElementSibling = this.children[this.children.length - 1] || null;
+        this.children.push(child);
+        child.previousElementSibling && (child.previousElementSibling.nextElementSibling = child);
+      }
+      this.childNodes.push(child);
+      child.parentNode = this;
+    },
+
+    removeChild: function (child) {
+      var childNodes = this.childNodes;
+      var childIndex = childNodes.indexOf(child);
+      if (childIndex === -1) {
+        throw "removeChild: node not found";
+      } else {
+        child.parentNode = null;
+        var prev = child.previousSibling;
+        var next = child.nextSibling;
+        if (prev)
+          prev.nextSibling = next;
+        if (next)
+          next.previousSibling = prev;
+
+        if (child.nodeType === Node.ELEMENT_NODE) {
+          prev = child.previousElementSibling;
+          next = child.nextElementSibling;
+          if (prev)
+            prev.nextElementSibling = next;
+          if (next)
+            next.previousElementSibling = prev;
+          this.children.splice(this.children.indexOf(child), 1);
+        }
+
+        child.previousSibling = child.nextSibling = null;
+        child.previousElementSibling = child.nextElementSibling = null;
+
+        return childNodes.splice(childIndex, 1)[0];
+      }
+    },
+
+    replaceChild: function (newNode, oldNode) {
+      var childNodes = this.childNodes;
+      var childIndex = childNodes.indexOf(oldNode);
+      if (childIndex === -1) {
+        throw "replaceChild: node not found";
+      } else {
+        // This will take care of updating the new node if it was somewhere else before:
+        if (newNode.parentNode)
+          newNode.parentNode.removeChild(newNode);
+
+        childNodes[childIndex] = newNode;
+
+        // update the new node's sibling properties, and its new siblings' sibling properties
+        newNode.nextSibling = oldNode.nextSibling;
+        newNode.previousSibling = oldNode.previousSibling;
+        if (newNode.nextSibling)
+          newNode.nextSibling.previousSibling = newNode;
+        if (newNode.previousSibling)
+          newNode.previousSibling.nextSibling = newNode;
+
+        newNode.parentNode = this;
+
+        // Now deal with elements before we clear out those values for the old node,
+        // because it can help us take shortcuts here:
+        if (newNode.nodeType === Node.ELEMENT_NODE) {
+          if (oldNode.nodeType === Node.ELEMENT_NODE) {
+            // Both were elements, which makes this easier, we just swap things out:
+            newNode.previousElementSibling = oldNode.previousElementSibling;
+            newNode.nextElementSibling = oldNode.nextElementSibling;
+            if (newNode.previousElementSibling)
+              newNode.previousElementSibling.nextElementSibling = newNode;
+            if (newNode.nextElementSibling)
+              newNode.nextElementSibling.previousElementSibling = newNode;
+            this.children[this.children.indexOf(oldNode)] = newNode;
+          } else {
+            // Hard way:
+            newNode.previousElementSibling = (function() {
+              for (var i = childIndex - 1; i >= 0; i--) {
+                if (childNodes[i].nodeType === Node.ELEMENT_NODE)
+                  return childNodes[i];
+              }
+              return null;
+            })();
+            if (newNode.previousElementSibling) {
+              newNode.nextElementSibling = newNode.previousElementSibling.nextElementSibling;
+            } else {
+              newNode.nextElementSibling = (function() {
+                for (var i = childIndex + 1; i < childNodes.length; i++) {
+                  if (childNodes[i].nodeType === Node.ELEMENT_NODE)
+                    return childNodes[i];
+                }
+                return null;
+              })();
+            }
+            if (newNode.previousElementSibling)
+              newNode.previousElementSibling.nextElementSibling = newNode;
+            if (newNode.nextElementSibling)
+              newNode.nextElementSibling.previousElementSibling = newNode;
+
+            if (newNode.nextElementSibling)
+              this.children.splice(this.children.indexOf(newNode.nextElementSibling), 0, newNode);
+            else
+              this.children.push(newNode);
+          }
+        } else if (oldNode.nodeType === Node.ELEMENT_NODE) {
+          // new node is not an element node.
+          // if the old one was, update its element siblings:
+          if (oldNode.previousElementSibling)
+            oldNode.previousElementSibling.nextElementSibling = oldNode.nextElementSibling;
+          if (oldNode.nextElementSibling)
+            oldNode.nextElementSibling.previousElementSibling = oldNode.previousElementSibling;
+          this.children.splice(this.children.indexOf(oldNode), 1);
+
+          // If the old node wasn't an element, neither the new nor the old node was an element,
+          // and the children array and its members shouldn't need any updating.
+        }
+
+
+        oldNode.parentNode = null;
+        oldNode.previousSibling = null;
+        oldNode.nextSibling = null;
+        if (oldNode.nodeType === Node.ELEMENT_NODE) {
+          oldNode.previousElementSibling = null;
+          oldNode.nextElementSibling = null;
+        }
+        return oldNode;
+      }
+    },
+
+    __JSDOMParser__: true,
+  };
+
+  for (var nodeType in nodeTypes) {
+    Node[nodeType] = Node.prototype[nodeType] = nodeTypes[nodeType];
+  }
+
+  var Attribute = function (name, value) {
+    this.name = name;
+    this._value = value;
+  };
+
+  Attribute.prototype = {
+    get value() {
+      return this._value;
+    },
+    setValue: function(newValue) {
+      this._value = newValue;
+    },
+    getEncodedValue: function() {
+      return encodeHTML(this._value);
+    },
+  };
+
+  var Comment = function () {
+    this.childNodes = [];
+  };
+
+  Comment.prototype = {
+    __proto__: Node.prototype,
+
+    nodeName: "#comment",
+    nodeType: Node.COMMENT_NODE
+  };
+
+  var Text = function () {
+    this.childNodes = [];
+  };
+
+  Text.prototype = {
+    __proto__: Node.prototype,
+
+    nodeName: "#text",
+    nodeType: Node.TEXT_NODE,
+    get textContent() {
+      if (typeof this._textContent === "undefined") {
+        this._textContent = decodeHTML(this._innerHTML || "");
+      }
+      return this._textContent;
+    },
+    get innerHTML() {
+      if (typeof this._innerHTML === "undefined") {
+        this._innerHTML = encodeTextContentHTML(this._textContent || "");
+      }
+      return this._innerHTML;
+    },
+
+    set innerHTML(newHTML) {
+      this._innerHTML = newHTML;
+      delete this._textContent;
+    },
+    set textContent(newText) {
+      this._textContent = newText;
+      delete this._innerHTML;
+    },
+  };
+
+  var Document = function (url) {
+    this.documentURI = url;
+    this.styleSheets = [];
+    this.childNodes = [];
+    this.children = [];
+  };
+
+  Document.prototype = {
+    __proto__: Node.prototype,
+
+    nodeName: "#document",
+    nodeType: Node.DOCUMENT_NODE,
+    title: "",
+
+    getElementsByTagName: getElementsByTagName,
+
+    getElementById: function (id) {
+      function getElem(node) {
+        var length = node.children.length;
+        if (node.id === id)
+          return node;
+        for (var i = 0; i < length; i++) {
+          var el = getElem(node.children[i]);
+          if (el)
+            return el;
+        }
+        return null;
+      }
+      return getElem(this);
+    },
+
+    createElement: function (tag) {
+      var node = new Element(tag);
+      return node;
+    },
+
+    createTextNode: function (text) {
+      var node = new Text();
+      node.textContent = text;
+      return node;
+    },
+
+    get baseURI() {
+      if (!this.hasOwnProperty("_baseURI")) {
+        this._baseURI = this.documentURI;
+        var baseElements = this.getElementsByTagName("base");
+        var href = baseElements[0] && baseElements[0].getAttribute("href");
+        if (href) {
+          try {
+            this._baseURI = (new URL(href, this._baseURI)).href;
+          } catch (ex) {/* Just fall back to documentURI */}
+        }
+      }
+      return this._baseURI;
+    },
+  };
+
+  var Element = function (tag) {
+    // We use this to find the closing tag.
+    this._matchingTag = tag;
+    // We're explicitly a non-namespace aware parser, we just pretend it's all HTML.
+    var lastColonIndex = tag.lastIndexOf(":");
+    if (lastColonIndex != -1) {
+      tag = tag.substring(lastColonIndex + 1);
+    }
+    this.attributes = [];
+    this.childNodes = [];
+    this.children = [];
+    this.nextElementSibling = this.previousElementSibling = null;
+    this.localName = tag.toLowerCase();
+    this.tagName = tag.toUpperCase();
+    this.style = new Style(this);
+  };
+
+  Element.prototype = {
+    __proto__: Node.prototype,
+
+    nodeType: Node.ELEMENT_NODE,
+
+    getElementsByTagName: getElementsByTagName,
+
+    get className() {
+      return this.getAttribute("class") || "";
+    },
+
+    set className(str) {
+      this.setAttribute("class", str);
+    },
+
+    get id() {
+      return this.getAttribute("id") || "";
+    },
+
+    set id(str) {
+      this.setAttribute("id", str);
+    },
+
+    get href() {
+      return this.getAttribute("href") || "";
+    },
+
+    set href(str) {
+      this.setAttribute("href", str);
+    },
+
+    get src() {
+      return this.getAttribute("src") || "";
+    },
+
+    set src(str) {
+      this.setAttribute("src", str);
+    },
+
+    get srcset() {
+      return this.getAttribute("srcset") || "";
+    },
+
+    set srcset(str) {
+      this.setAttribute("srcset", str);
+    },
+
+    get nodeName() {
+      return this.tagName;
+    },
+
+    get innerHTML() {
+      function getHTML(node) {
+        var i = 0;
+        for (i = 0; i < node.childNodes.length; i++) {
+          var child = node.childNodes[i];
+          if (child.localName) {
+            arr.push("<" + child.localName);
+
+            // serialize attribute list
+            for (var j = 0; j < child.attributes.length; j++) {
+              var attr = child.attributes[j];
+              // the attribute value will be HTML escaped.
+              var val = attr.getEncodedValue();
+              var quote = (val.indexOf('"') === -1 ? '"' : "'");
+              arr.push(" " + attr.name + "=" + quote + val + quote);
+            }
+
+            if (child.localName in voidElems && !child.childNodes.length) {
+              // if this is a self-closing element, end it here
+              arr.push("/>");
+            } else {
+              // otherwise, add its children
+              arr.push(">");
+              getHTML(child);
+              arr.push("</" + child.localName + ">");
+            }
+          } else {
+            // This is a text node, so asking for innerHTML won't recurse.
+            arr.push(child.innerHTML);
+          }
+        }
+      }
+
+      // Using Array.join() avoids the overhead from lazy string concatenation.
+      var arr = [];
+      getHTML(this);
+      return arr.join("");
+    },
+
+    set innerHTML(html) {
+      var parser = new JSDOMParser();
+      var node = parser.parse(html);
+      var i;
+      for (i = this.childNodes.length; --i >= 0;) {
+        this.childNodes[i].parentNode = null;
+      }
+      this.childNodes = node.childNodes;
+      this.children = node.children;
+      for (i = this.childNodes.length; --i >= 0;) {
+        this.childNodes[i].parentNode = this;
+      }
+    },
+
+    set textContent(text) {
+      // clear parentNodes for existing children
+      for (var i = this.childNodes.length; --i >= 0;) {
+        this.childNodes[i].parentNode = null;
+      }
+
+      var node = new Text();
+      this.childNodes = [ node ];
+      this.children = [];
+      node.textContent = text;
+      node.parentNode = this;
+    },
+
+    get textContent() {
+      function getText(node) {
+        var nodes = node.childNodes;
+        for (var i = 0; i < nodes.length; i++) {
+          var child = nodes[i];
+          if (child.nodeType === 3) {
+            text.push(child.textContent);
+          } else {
+            getText(child);
+          }
+        }
+      }
+
+      // Using Array.join() avoids the overhead from lazy string concatenation.
+      // See http://blog.cdleary.com/2012/01/string-representation-in-spidermonkey/#ropes
+      var text = [];
+      getText(this);
+      return text.join("");
+    },
+
+    getAttribute: function (name) {
+      for (var i = this.attributes.length; --i >= 0;) {
+        var attr = this.attributes[i];
+        if (attr.name === name) {
+          return attr.value;
+        }
+      }
+      return undefined;
+    },
+
+    setAttribute: function (name, value) {
+      for (var i = this.attributes.length; --i >= 0;) {
+        var attr = this.attributes[i];
+        if (attr.name === name) {
+          attr.setValue(value);
+          return;
+        }
+      }
+      this.attributes.push(new Attribute(name, value));
+    },
+
+    removeAttribute: function (name) {
+      for (var i = this.attributes.length; --i >= 0;) {
+        var attr = this.attributes[i];
+        if (attr.name === name) {
+          this.attributes.splice(i, 1);
+          break;
+        }
+      }
+    },
+
+    hasAttribute: function (name) {
+      return this.attributes.some(function (attr) {
+        return attr.name == name;
+      });
+    },
+  };
+
+  var Style = function (node) {
+    this.node = node;
+  };
+
+  // getStyle() and setStyle() use the style attribute string directly. This
+  // won't be very efficient if there are a lot of style manipulations, but
+  // it's the easiest way to make sure the style attribute string and the JS
+  // style property stay in sync. Readability.js doesn't do many style
+  // manipulations, so this should be okay.
+  Style.prototype = {
+    getStyle: function (styleName) {
+      var attr = this.node.getAttribute("style");
+      if (!attr)
+        return undefined;
+
+      var styles = attr.split(";");
+      for (var i = 0; i < styles.length; i++) {
+        var style = styles[i].split(":");
+        var name = style[0].trim();
+        if (name === styleName)
+          return style[1].trim();
+      }
+
+      return undefined;
+    },
+
+    setStyle: function (styleName, styleValue) {
+      var value = this.node.getAttribute("style") || "";
+      var index = 0;
+      do {
+        var next = value.indexOf(";", index) + 1;
+        var length = next - index - 1;
+        var style = (length > 0 ? value.substr(index, length) : value.substr(index));
+        if (style.substr(0, style.indexOf(":")).trim() === styleName) {
+          value = value.substr(0, index).trim() + (next ? " " + value.substr(next).trim() : "");
+          break;
+        }
+        index = next;
+      } while (index);
+
+      value += " " + styleName + ": " + styleValue + ";";
+      this.node.setAttribute("style", value.trim());
+    }
+  };
+
+  // For each item in styleMap, define a getter and setter on the style
+  // property.
+  for (var jsName in styleMap) {
+    (function (cssName) {
+      Style.prototype.__defineGetter__(jsName, function () {
+        return this.getStyle(cssName);
+      });
+      Style.prototype.__defineSetter__(jsName, function (value) {
+        this.setStyle(cssName, value);
+      });
+    })(styleMap[jsName]);
+  }
+
+  var JSDOMParser = function () {
+    this.currentChar = 0;
+
+    // In makeElementNode() we build up many strings one char at a time. Using
+    // += for this results in lots of short-lived intermediate strings. It's
+    // better to build an array of single-char strings and then join() them
+    // together at the end. And reusing a single array (i.e. |this.strBuf|)
+    // over and over for this purpose uses less memory than using a new array
+    // for each string.
+    this.strBuf = [];
+
+    // Similarly, we reuse this array to return the two arguments from
+    // makeElementNode(), which saves us from having to allocate a new array
+    // every time.
+    this.retPair = [];
+
+    this.errorState = "";
+  };
+
+  JSDOMParser.prototype = {
+    error: function(m) {
+      if (typeof console !== "undefined") {
+        console.log("JSDOMParser error: " + m + "\n");
+      } else if (typeof dump !== "undefined") {
+        /* global dump */
+        dump("JSDOMParser error: " + m + "\n");
+      }
+      this.errorState += m + "\n";
+    },
+
+    /**
+     * Look at the next character without advancing the index.
+     */
+    peekNext: function () {
+      return this.html[this.currentChar];
+    },
+
+    /**
+     * Get the next character and advance the index.
+     */
+    nextChar: function () {
+      return this.html[this.currentChar++];
+    },
+
+    /**
+     * Called after a quote character is read. This finds the next quote
+     * character and returns the text string in between.
+     */
+    readString: function (quote) {
+      var str;
+      var n = this.html.indexOf(quote, this.currentChar);
+      if (n === -1) {
+        this.currentChar = this.html.length;
+        str = null;
+      } else {
+        str = this.html.substring(this.currentChar, n);
+        this.currentChar = n + 1;
+      }
+
+      return str;
+    },
+
+    /**
+     * Called when parsing a node. This finds the next name/value attribute
+     * pair and adds the result to the attributes list.
+     */
+    readAttribute: function (node) {
+      var name = "";
+
+      var n = this.html.indexOf("=", this.currentChar);
+      if (n === -1) {
+        this.currentChar = this.html.length;
+      } else {
+        // Read until a '=' character is hit; this will be the attribute key
+        name = this.html.substring(this.currentChar, n);
+        this.currentChar = n + 1;
+      }
+
+      if (!name)
+        return;
+
+      // After a '=', we should see a '"' for the attribute value
+      var c = this.nextChar();
+      if (c !== '"' && c !== "'") {
+        this.error("Error reading attribute " + name + ", expecting '\"'");
+        return;
+      }
+
+      // Read the attribute value (and consume the matching quote)
+      var value = this.readString(c);
+
+      node.attributes.push(new Attribute(name, decodeHTML(value)));
+
+      return;
+    },
+
+    /**
+     * Parses and returns an Element node. This is called after a '<' has been
+     * read.
+     *
+     * @returns an array; the first index of the array is the parsed node;
+     *          the second index is a boolean indicating whether this is a void
+     *          Element
+     */
+    makeElementNode: function (retPair) {
+      var c = this.nextChar();
+
+      // Read the Element tag name
+      var strBuf = this.strBuf;
+      strBuf.length = 0;
+      while (whitespace.indexOf(c) == -1 && c !== ">" && c !== "/") {
+        if (c === undefined)
+          return false;
+        strBuf.push(c);
+        c = this.nextChar();
+      }
+      var tag = strBuf.join("");
+
+      if (!tag)
+        return false;
+
+      var node = new Element(tag);
+
+      // Read Element attributes
+      while (c !== "/" && c !== ">") {
+        if (c === undefined)
+          return false;
+        while (whitespace.indexOf(this.html[this.currentChar++]) != -1) {
+          // Advance cursor to first non-whitespace char.
+        }
+        this.currentChar--;
+        c = this.nextChar();
+        if (c !== "/" && c !== ">") {
+          --this.currentChar;
+          this.readAttribute(node);
+        }
+      }
+
+      // If this is a self-closing tag, read '/>'
+      var closed = false;
+      if (c === "/") {
+        closed = true;
+        c = this.nextChar();
+        if (c !== ">") {
+          this.error("expected '>' to close " + tag);
+          return false;
+        }
+      }
+
+      retPair[0] = node;
+      retPair[1] = closed;
+      return true;
+    },
+
+    /**
+     * If the current input matches this string, advance the input index;
+     * otherwise, do nothing.
+     *
+     * @returns whether input matched string
+     */
+    match: function (str) {
+      var strlen = str.length;
+      if (this.html.substr(this.currentChar, strlen).toLowerCase() === str.toLowerCase()) {
+        this.currentChar += strlen;
+        return true;
+      }
+      return false;
+    },
+
+    /**
+     * Searches the input until a string is found and discards all input up to
+     * and including the matched string.
+     */
+    discardTo: function (str) {
+      var index = this.html.indexOf(str, this.currentChar) + str.length;
+      if (index === -1)
+        this.currentChar = this.html.length;
+      this.currentChar = index;
+    },
+
+    /**
+     * Reads child nodes for the given node.
+     */
+    readChildren: function (node) {
+      var child;
+      while ((child = this.readNode())) {
+        // Don't keep Comment nodes
+        if (child.nodeType !== 8) {
+          node.appendChild(child);
+        }
+      }
+    },
+
+    discardNextComment: function() {
+      if (this.match("--")) {
+        this.discardTo("-->");
+      } else {
+        var c = this.nextChar();
+        while (c !== ">") {
+          if (c === undefined)
+            return null;
+          if (c === '"' || c === "'")
+            this.readString(c);
+          c = this.nextChar();
+        }
+      }
+      return new Comment();
+    },
+
+
+    /**
+     * Reads the next child node from the input. If we're reading a closing
+     * tag, or if we've reached the end of input, return null.
+     *
+     * @returns the node
+     */
+    readNode: function () {
+      var c = this.nextChar();
+
+      if (c === undefined)
+        return null;
+
+      // Read any text as Text node
+      var textNode;
+      if (c !== "<") {
+        --this.currentChar;
+        textNode = new Text();
+        var n = this.html.indexOf("<", this.currentChar);
+        if (n === -1) {
+          textNode.innerHTML = this.html.substring(this.currentChar, this.html.length);
+          this.currentChar = this.html.length;
+        } else {
+          textNode.innerHTML = this.html.substring(this.currentChar, n);
+          this.currentChar = n;
+        }
+        return textNode;
+      }
+
+      if (this.match("![CDATA[")) {
+        var endChar = this.html.indexOf("]]>", this.currentChar);
+        if (endChar === -1) {
+          this.error("unclosed CDATA section");
+          return null;
+        }
+        textNode = new Text();
+        textNode.textContent = this.html.substring(this.currentChar, endChar);
+        this.currentChar = endChar + ("]]>").length;
+        return textNode;
+      }
+
+      c = this.peekNext();
+
+      // Read Comment node. Normally, Comment nodes know their inner
+      // textContent, but we don't really care about Comment nodes (we throw
+      // them away in readChildren()). So just returning an empty Comment node
+      // here is sufficient.
+      if (c === "!" || c === "?") {
+        // We're still before the ! or ? that is starting this comment:
+        this.currentChar++;
+        return this.discardNextComment();
+      }
+
+      // If we're reading a closing tag, return null. This means we've reached
+      // the end of this set of child nodes.
+      if (c === "/") {
+        --this.currentChar;
+        return null;
+      }
+
+      // Otherwise, we're looking at an Element node
+      var result = this.makeElementNode(this.retPair);
+      if (!result)
+        return null;
+
+      var node = this.retPair[0];
+      var closed = this.retPair[1];
+      var localName = node.localName;
+
+      // If this isn't a void Element, read its child nodes
+      if (!closed) {
+        this.readChildren(node);
+        var closingTag = "</" + node._matchingTag + ">";
+        if (!this.match(closingTag)) {
+          this.error("expected '" + closingTag + "' and got " + this.html.substr(this.currentChar, closingTag.length));
+          return null;
+        }
+      }
+
+      // Only use the first title, because SVG might have other
+      // title elements which we don't care about (medium.com
+      // does this, at least).
+      if (localName === "title" && !this.doc.title) {
+        this.doc.title = node.textContent.trim();
+      } else if (localName === "head") {
+        this.doc.head = node;
+      } else if (localName === "body") {
+        this.doc.body = node;
+      } else if (localName === "html") {
+        this.doc.documentElement = node;
+      }
+
+      return node;
+    },
+
+    /**
+     * Parses an HTML string and returns a JS implementation of the Document.
+     */
+    parse: function (html, url) {
+      this.html = html;
+      var doc = this.doc = new Document(url);
+      this.readChildren(doc);
+
+      // If this is an HTML document, remove root-level children except for the
+      // <html> node
+      if (doc.documentElement) {
+        for (var i = doc.childNodes.length; --i >= 0;) {
+          var child = doc.childNodes[i];
+          if (child !== doc.documentElement) {
+            doc.removeChild(child);
+          }
+        }
+      }
+
+      return doc;
+    }
+  };
+
+  // Attach the standard DOM types to the global scope
+  global.Node = Node;
+  global.Comment = Comment;
+  global.Document = Document;
+  global.Element = Element;
+  global.Text = Text;
+
+  // Attach JSDOMParser to the global scope
+  global.JSDOMParser = JSDOMParser;
+
+})(this);
+
+if (typeof module === "object") {
+  /* global module */
+  module.exports = this.JSDOMParser;
+}
diff --git a/toolkit/components/reader/readability/LICENSE.md b/toolkit/components/reader/readability/LICENSE.md
new file mode 100644
index 0000000000..ca8e58b203
--- /dev/null
+++ b/toolkit/components/reader/readability/LICENSE.md
@@ -0,0 +1,13 @@
+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.
diff --git a/toolkit/components/reader/readability/Readability-readerable.js b/toolkit/components/reader/readability/Readability-readerable.js
new file mode 100644
index 0000000000..892169fb94
--- /dev/null
+++ b/toolkit/components/reader/readability/Readability-readerable.js
@@ -0,0 +1,108 @@
+/*
+ * 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 REGEXPS = {
+  // NOTE: These two regular expressions are duplicated in
+  // Readability.js. Please keep both copies in sync.
+  unlikelyCandidates: /-ad-|ai2html|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|footer|gdpr|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|content|main|shadow/i,
+};
+
+function isNodeVisible(node) {
+  // Have to null-check node.style and node.className.indexOf to deal with SVG and MathML nodes.
+  return (!node.style || node.style.display != "none")
+    && !node.hasAttribute("hidden")
+    //check for "fallback-image" so that wikimedia math images are displayed
+    && (!node.hasAttribute("aria-hidden") || node.getAttribute("aria-hidden") != "true" || (node.className && node.className.indexOf && node.className.indexOf("fallback-image") !== -1));
+}
+
+/**
+ * Decides whether or not the document is reader-able without parsing the whole thing.
+ * @param {Object} options Configuration object.
+ * @param {number} [options.minContentLength=140] The minimum node content length used to decide if the document is readerable.
+ * @param {number} [options.minScore=20] The minumum cumulated 'score' used to determine if the document is readerable.
+ * @param {Function} [options.visibilityChecker=isNodeVisible] The function used to determine if a node is visible.
+ * @return {boolean} Whether or not we suspect Readability.parse() will suceeed at returning an article object.
+ */
+function isProbablyReaderable(doc, options = {}) {
+  // For backward compatibility reasons 'options' can either be a configuration object or the function used
+  // to determine if a node is visible.
+  if (typeof options == "function") {
+    options = { visibilityChecker: options };
+  }
+
+  var defaultOptions = { minScore: 20, minContentLength: 140, visibilityChecker: isNodeVisible };
+  options = Object.assign(defaultOptions, options);
+
+  var nodes = doc.querySelectorAll("p, pre, article");
+
+  // 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);
+    });
+    nodes = Array.from(set);
+  }
+
+  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 (!options.visibilityChecker(node)) {
+      return false;
+    }
+
+    var matchString = node.className + " " + node.id;
+    if (REGEXPS.unlikelyCandidates.test(matchString) &&
+        !REGEXPS.okMaybeItsACandidate.test(matchString)) {
+      return false;
+    }
+
+    if (node.matches("li p")) {
+      return false;
+    }
+
+    var textContentLength = node.textContent.trim().length;
+    if (textContentLength < options.minContentLength) {
+      return false;
+    }
+
+    score += Math.sqrt(textContentLength - options.minContentLength);
+
+    if (score > options.minScore) {
+      return true;
+    }
+    return false;
+  });
+}
+
+if (typeof module === "object") {
+  /* global module */
+  module.exports = isProbablyReaderable;
+}
diff --git a/toolkit/components/reader/readability/Readability.js b/toolkit/components/reader/readability/Readability.js
new file mode 100644
index 0000000000..b745aa01d8
--- /dev/null
+++ b/toolkit/components/reader/readability/Readability.js
@@ -0,0 +1,2314 @@
+/*
+ * 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
+ */
+
+/**
+ * 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._docJSDOMParser = this._doc.firstChild.__JSDOMParser__;
+  this._articleTitle = null;
+  this._articleByline = null;
+  this._articleDir = null;
+  this._articleSiteName = 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 || []);
+  this._keepClasses = !!options.keepClasses;
+  this._serializer = options.serializer || function(el) {
+    return el.innerHTML;
+  };
+  this._disableJSONLD = !!options.disableJSONLD;
+  this._allowedVideoRegex = options.allowedVideoRegex || this.REGEXPS.videos;
+
+  // Start with all flags set
+  this._flags = this.FLAG_STRIP_UNLIKELYS |
+                this.FLAG_WEIGHT_CLASSES |
+                this.FLAG_CLEAN_CONDITIONALLY;
+
+
+  // Control whether log messages are sent to the console
+  if (this._debug) {
+    let logNode = function(node) {
+      if (node.nodeType == node.TEXT_NODE) {
+        return `${node.nodeName} ("${node.textContent}")`;
+      }
+      let attrPairs = Array.from(node.attributes || [], function(attr) {
+        return `${attr.name}="${attr.value}"`;
+      }).join(" ");
+      return `<${node.localName} ${attrPairs}>`;
+    };
+    this.log = function () {
+      if (typeof console !== "undefined") {
+        let args = Array.from(arguments, arg => {
+          if (arg && arg.nodeType == this.ELEMENT_NODE) {
+            return logNode(arg);
+          }
+          return arg;
+        });
+        args.unshift("Reader: (Readability)");
+        console.log.apply(console, args);
+      } else if (typeof dump !== "undefined") {
+        /* global dump */
+        var msg = Array.prototype.map.call(arguments, function(x) {
+          return (x && x.nodeName) ? logNode(x) : x;
+        }).join(" ");
+        dump("Reader: (Readability) " + msg + "\n");
+      }
+    };
+  } else {
+    this.log = function () {};
+  }
+}
+
+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: {
+    // NOTE: These two regular expressions are duplicated in
+    // Readability-readerable.js. Please keep both copies in sync.
+    unlikelyCandidates: /-ad-|ai2html|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|footer|gdpr|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|content|main|shadow/i,
+
+    positive: /article|body|content|entry|hentry|h-entry|main|page|pagination|post|text|blog|story/i,
+    negative: /-ad-|hidden|^hid$| hid$| hid |^hid |banner|combx|comment|com-|contact|foot|footer|footnote|gdpr|masthead|media|meta|outbrain|promo|related|scroll|share|shoutbox|sidebar|skyscraper|sponsor|shopping|tags|tool|widget/i,
+    extraneous: /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,
+    byline: /byline|author|dateline|writtenby|p-author/i,
+    replaceFonts: /<(\/?)font[^>]*>/gi,
+    normalize: /\s{2,}/g,
+    videos: /\/\/(www\.)?((dailymotion|youtube|youtube-nocookie|player\.vimeo|v\.qq)\.com|(archive|upload\.wikimedia)\.org|player\.twitch\.tv)/i,
+    shareElements: /(\b|_)(share|sharedaddy)(\b|_)/i,
+    nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
+    prevLink: /(prev|earl|old|new|<|«)/i,
+    tokenize: /\W+/g,
+    whitespace: /^\s*$/,
+    hasContent: /\S$/,
+    hashUrl: /^#.+/,
+    srcsetUrl: /(\S+)(\s+[\d.]+[xw])?(\s*(?:,|$))/g,
+    b64DataUrl: /^data:\s*([^\s;,]+)\s*;\s*base64\s*,/i,
+    // Commas as used in Latin, Sindhi, Chinese and various other scripts.
+    // see: https://en.wikipedia.org/wiki/Comma#Comma_variants
+    commas: /\u002C|\u060C|\uFE50|\uFE10|\uFE11|\u2E41|\u2E34|\u2E32|\uFF0C/g,
+    // See: https://schema.org/Article
+    jsonLdArticleTypes: /^Article|AdvertiserContentArticle|NewsArticle|AnalysisNewsArticle|AskPublicNewsArticle|BackgroundNewsArticle|OpinionNewsArticle|ReportageNewsArticle|ReviewNewsArticle|Report|SatiricalArticle|ScholarlyArticle|MedicalScholarlyArticle|SocialMediaPosting|BlogPosting|LiveBlogPosting|DiscussionForumPosting|TechArticle|APIReference$/
+  },
+
+  UNLIKELY_ROLES: [ "menu", "menubar", "complementary", "navigation", "alert", "alertdialog", "dialog" ],
+
+  DIV_TO_P_ELEMS: new Set([ "BLOCKQUOTE", "DL", "DIV", "IMG", "OL", "P", "PRE", "TABLE", "UL" ]),
+
+  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" ],
+
+  // These are the list of HTML entities that need to be escaped.
+  HTML_ESCAPE_MAP: {
+    "lt": "<",
+    "gt": ">",
+    "amp": "&",
+    "quot": '"',
+    "apos": "'",
+  },
+
+  /**
+   * 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);
+
+    this._simplifyNestedElements(articleContent);
+
+    if (!this._keepClasses) {
+      // 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) {
+    // Avoid ever operating on live node lists.
+    if (this._docJSDOMParser && nodeList._isLiveNodeList) {
+      throw new Error("Do not pass live node lists to _removeNodes");
+    }
+    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) {
+    // Avoid ever operating on live node lists.
+    if (this._docJSDOMParser && nodeList._isLiveNodeList) {
+      throw new Error("Do not pass live node lists to _replaceNodeTags");
+    }
+    for (const node of nodeList) {
+      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, and return the first node that passes
+   * the supplied test function
+   *
+   * For convenience, the current object context is applied to the provided
+   * test function.
+   *
+   * @param  NodeList nodeList The NodeList.
+   * @param  Function fn       The test function.
+   * @return void
+   */
+  _findNode: function(nodeList, fn) {
+    return Array.prototype.find.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);
+  },
+
+  /**
+   * 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 = this._getAllNodesWithTag(articleContent, ["a"]);
+    this._forEachNode(links, function(link) {
+      var href = link.getAttribute("href");
+      if (href) {
+        // Remove links with javascript: URIs, since
+        // they won't work after scripts have been removed from the page.
+        if (href.indexOf("javascript:") === 0) {
+          // if the link only contains simple text content, it can be converted to a text node
+          if (link.childNodes.length === 1 && link.childNodes[0].nodeType === this.TEXT_NODE) {
+            var text = this._doc.createTextNode(link.textContent);
+            link.parentNode.replaceChild(text, link);
+          } else {
+            // if the link has multiple children, they should all be preserved
+            var container = this._doc.createElement("span");
+            while (link.firstChild) {
+              container.appendChild(link.firstChild);
+            }
+            link.parentNode.replaceChild(container, link);
+          }
+        } else {
+          link.setAttribute("href", toAbsoluteURI(href));
+        }
+      }
+    });
+
+    var medias = this._getAllNodesWithTag(articleContent, [
+      "img", "picture", "figure", "video", "audio", "source"
+    ]);
+
+    this._forEachNode(medias, function(media) {
+      var src = media.getAttribute("src");
+      var poster = media.getAttribute("poster");
+      var srcset = media.getAttribute("srcset");
+
+      if (src) {
+        media.setAttribute("src", toAbsoluteURI(src));
+      }
+
+      if (poster) {
+        media.setAttribute("poster", toAbsoluteURI(poster));
+      }
+
+      if (srcset) {
+        var newSrcset = srcset.replace(this.REGEXPS.srcsetUrl, function(_, p1, p2, p3) {
+          return toAbsoluteURI(p1) + (p2 || "") + p3;
+        });
+
+        media.setAttribute("srcset", newSrcset);
+      }
+    });
+  },
+
+  _simplifyNestedElements: function(articleContent) {
+    var node = articleContent;
+
+    while (node) {
+      if (node.parentNode && ["DIV", "SECTION"].includes(node.tagName) && !(node.id && node.id.startsWith("readability"))) {
+        if (this._isElementWithoutContent(node)) {
+          node = this._removeAndGetNext(node);
+          continue;
+        } else if (this._hasSingleTagInsideElement(node, "DIV") || this._hasSingleTagInsideElement(node, "SECTION")) {
+          var child = node.children[0];
+          for (var i = 0; i < node.attributes.length; i++) {
+            child.setAttribute(node.attributes[i].name, node.attributes[i].value);
+          }
+          node.parentNode.replaceChild(child, node);
+          node = child;
+          continue;
+        }
+      }
+
+      node = this._getNextNode(node);
+    }
+  },
+
+  /**
+   * Get the article title as an H1.
+   *
+   * @return string
+   **/
+  _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);
+
+        // 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().replace(this.REGEXPS.normalize, " ");
+    // 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(this._getAllNodesWithTag(doc, ["style"]));
+
+    if (doc.body) {
+      this._replaceBrs(doc.body);
+    }
+
+    this._replaceNodeTags(this._getAllNodesWithTag(doc, ["font"]), "SPAN");
+  },
+
+  /**
+   * Finds the next node, starting from the given node, and ignoring
+   * whitespace in between. If the given node is an element, the same node is
+   * returned.
+   */
+  _nextNode: 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 node
+      // or non-whitespace. This leaves behind the first <br> in the chain
+      // (which will be replaced with a <p> later).
+      while ((next = this._nextNode(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._nextNode(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");
+      }
+    });
+  },
+
+  _setNodeTag: function (node, tag) {
+    this.log("_setNodeTag", node, tag);
+    if (this._docJSDOMParser) {
+      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++) {
+      try {
+        replacement.setAttribute(node.attributes[i].name, node.attributes[i].value);
+      } catch (ex) {
+        /* it's possible for setAttribute() to throw if the attribute name
+         * isn't a valid XML Name. Such attributes can however be parsed from
+         * source in HTML docs, see https://github.com/whatwg/html/issues/4275,
+         * so we can hit them here and then throw. We don't care about such
+         * attributes so we ignore them.
+         */
+      }
+    }
+    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);
+
+    // 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);
+
+    this._fixLazyImages(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, "footer");
+    this._clean(articleContent, "link");
+    this._clean(articleContent, "aside");
+
+    // Clean out elements with little content that have "share" in their id/class combinations from final top candidates,
+    // which means we don't remove the top candidates even they have "share".
+
+    var shareElementThreshold = this.DEFAULT_CHAR_THRESHOLD;
+
+    this._forEachNode(articleContent.children, function (topCandidate) {
+      this._cleanMatchedNodes(topCandidate, function (node, matchString) {
+        return this.REGEXPS.shareElements.test(matchString) && node.textContent.length < shareElementThreshold;
+      });
+    });
+
+    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");
+
+    // replace H1 with H2 as H1 should be only title that is displayed separately
+    this._replaceNodeTags(this._getAllNodesWithTag(articleContent, ["h1"]), "h2");
+
+    // Remove extra paragraphs
+    this._removeNodes(this._getAllNodesWithTag(articleContent, ["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._nextNode(br.nextSibling);
+      if (next && next.tagName == "P")
+        br.parentNode.removeChild(br);
+    });
+
+    // 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;
+  },
+
+  // compares second text to first one
+  // 1 = same text, 0 = completely different text
+  // works the way that it splits both texts into words and then finds words that are unique in second text
+  // the result is given by the lower length of unique parts
+  _textSimilarity: function(textA, textB) {
+    var tokensA = textA.toLowerCase().split(this.REGEXPS.tokenize).filter(Boolean);
+    var tokensB = textB.toLowerCase().split(this.REGEXPS.tokenize).filter(Boolean);
+    if (!tokensA.length || !tokensB.length) {
+      return 0;
+    }
+    var uniqTokensB = tokensB.filter(token => !tokensA.includes(token));
+    var distanceB = uniqTokensB.join(" ").length / tokensB.join(" ").length;
+    return 1 - distanceB;
+  },
+
+  _checkByline: function(node, matchString) {
+    if (this._articleByline) {
+      return false;
+    }
+
+    if (node.getAttribute !== undefined) {
+      var rel = node.getAttribute("rel");
+      var itemprop = node.getAttribute("itemprop");
+    }
+
+    if ((rel === "author" || (itemprop && itemprop.indexOf("author") !== -1) || 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;
+    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;
+    }
+
+    var pageCacheHtml = page.innerHTML;
+
+    while (true) {
+      this.log("Starting grabArticle loop");
+      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;
+
+      let shouldRemoveTitleHeader = true;
+
+      while (node) {
+
+        if (node.tagName === "HTML") {
+          this._articleLang = node.getAttribute("lang");
+        }
+
+        var matchString = node.className + " " + node.id;
+
+        if (!this._isProbablyVisible(node)) {
+          this.log("Removing hidden node - " + matchString);
+          node = this._removeAndGetNext(node);
+          continue;
+        }
+
+        // User is not able to see elements applied with both "aria-modal = true" and "role = dialog"
+        if (node.getAttribute("aria-modal") == "true" && node.getAttribute("role") == "dialog") {
+          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;
+        }
+
+        if (shouldRemoveTitleHeader && this._headerDuplicatesTitle(node)) {
+          this.log("Removing header: ", node.textContent.trim(), this._articleTitle.trim());
+          shouldRemoveTitleHeader = false;
+          node = this._removeAndGetNext(node);
+          continue;
+        }
+
+        // Remove unlikely candidates
+        if (stripUnlikelyCandidates) {
+          if (this.REGEXPS.unlikelyCandidates.test(matchString) &&
+              !this.REGEXPS.okMaybeItsACandidate.test(matchString) &&
+              !this._hasAncestorTag(node, "table") &&
+              !this._hasAncestorTag(node, "code") &&
+              node.tagName !== "BODY" &&
+              node.tagName !== "A") {
+            this.log("Removing unlikely candidate - " + matchString);
+            node = this._removeAndGetNext(node);
+            continue;
+          }
+
+          if (this.UNLIKELY_ROLES.includes(node.getAttribute("role"))) {
+            this.log("Removing content with role " + node.getAttribute("role") + " - " + 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, 5);
+        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(this.REGEXPS.commas).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:
+        while (page.firstChild) {
+          this.log("Moving child out:", page.firstChild);
+          topCandidate.appendChild(page.firstChild);
+        }
+
+        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);
+          // Fetch children again to make it compatible
+          // with DOM parsers without live collection support.
+          siblings = parentOfTopCandidate.children;
+          // 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";
+        while (articleContent.firstChild) {
+          div.appendChild(articleContent.firstChild);
+        }
+        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 b.textLength - a.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;
+  },
+
+  /**
+   * Converts some of the common HTML entities in string to their corresponding characters.
+   *
+   * @param str {string} - a string to unescape.
+   * @return string without HTML entity.
+   */
+  _unescapeHtmlEntities: function(str) {
+    if (!str) {
+      return str;
+    }
+
+    var htmlEscapeMap = this.HTML_ESCAPE_MAP;
+    return str.replace(/&(quot|amp|apos|lt|gt);/g, function(_, tag) {
+      return htmlEscapeMap[tag];
+    }).replace(/&#(?:x([0-9a-z]{1,4})|([0-9]{1,4}));/gi, function(_, hex, numStr) {
+      var num = parseInt(hex || numStr, hex ? 16 : 10);
+      return String.fromCharCode(num);
+    });
+  },
+
+  /**
+   * Try to extract metadata from JSON-LD object.
+   * For now, only Schema.org objects of type Article or its subtypes are supported.
+   * @return Object with any metadata that could be extracted (possibly none)
+   */
+  _getJSONLD: function (doc) {
+    var scripts = this._getAllNodesWithTag(doc, ["script"]);
+
+    var metadata;
+
+    this._forEachNode(scripts, function(jsonLdElement) {
+      if (!metadata && jsonLdElement.getAttribute("type") === "application/ld+json") {
+        try {
+          // Strip CDATA markers if present
+          var content = jsonLdElement.textContent.replace(/^\s*<!\[CDATA\[|\]\]>\s*$/g, "");
+          var parsed = JSON.parse(content);
+          if (
+            !parsed["@context"] ||
+            !parsed["@context"].match(/^https?\:\/\/schema\.org$/)
+          ) {
+            return;
+          }
+
+          if (!parsed["@type"] && Array.isArray(parsed["@graph"])) {
+            parsed = parsed["@graph"].find(function(it) {
+              return (it["@type"] || "").match(
+                this.REGEXPS.jsonLdArticleTypes
+              );
+            });
+          }
+
+          if (
+            !parsed ||
+            !parsed["@type"] ||
+            !parsed["@type"].match(this.REGEXPS.jsonLdArticleTypes)
+          ) {
+            return;
+          }
+
+          metadata = {};
+
+          if (typeof parsed.name === "string" && typeof parsed.headline === "string" && parsed.name !== parsed.headline) {
+            // we have both name and headline element in the JSON-LD. They should both be the same but some websites like aktualne.cz
+            // put their own name into "name" and the article title to "headline" which confuses Readability. So we try to check if either
+            // "name" or "headline" closely matches the html title, and if so, use that one. If not, then we use "name" by default.
+
+            var title = this._getArticleTitle();
+            var nameMatches = this._textSimilarity(parsed.name, title) > 0.75;
+            var headlineMatches = this._textSimilarity(parsed.headline, title) > 0.75;
+
+            if (headlineMatches && !nameMatches) {
+              metadata.title = parsed.headline;
+            } else {
+              metadata.title = parsed.name;
+            }
+          } else if (typeof parsed.name === "string") {
+            metadata.title = parsed.name.trim();
+          } else if (typeof parsed.headline === "string") {
+            metadata.title = parsed.headline.trim();
+          }
+          if (parsed.author) {
+            if (typeof parsed.author.name === "string") {
+              metadata.byline = parsed.author.name.trim();
+            } else if (Array.isArray(parsed.author) && parsed.author[0] && typeof parsed.author[0].name === "string") {
+              metadata.byline = parsed.author
+                .filter(function(author) {
+                  return author && typeof author.name === "string";
+                })
+                .map(function(author) {
+                  return author.name.trim();
+                })
+                .join(", ");
+            }
+          }
+          if (typeof parsed.description === "string") {
+            metadata.excerpt = parsed.description.trim();
+          }
+          if (
+            parsed.publisher &&
+            typeof parsed.publisher.name === "string"
+          ) {
+            metadata.siteName = parsed.publisher.name.trim();
+          }
+          if (typeof parsed.datePublished === "string") {
+            metadata.datePublished = parsed.datePublished.trim();
+          }
+          return;
+        } catch (err) {
+          this.log(err.message);
+        }
+      }
+    });
+    return metadata ? metadata : {};
+  },
+
+  /**
+   * Attempts to get excerpt and byline metadata for the article.
+   *
+   * @param {Object} jsonld — object containing any metadata that
+   * could be extracted from JSON-LD object.
+   *
+   * @return Object with optional "excerpt" and "byline" properties
+   */
+  _getArticleMetadata: function(jsonld) {
+    var metadata = {};
+    var values = {};
+    var metaElements = this._doc.getElementsByTagName("meta");
+
+    // property is a space-separated list of values
+    var propertyPattern = /\s*(article|dc|dcterm|og|twitter)\s*:\s*(author|creator|description|published_time|title|site_name)\s*/gi;
+
+    // name is a single value
+    var namePattern = /^\s*(?:(dc|dcterm|og|twitter|weibo:(article|webpage))\s*[\.:]\s*)?(author|creator|description|title|site_name)\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");
+      if (!content) {
+        return;
+      }
+      var matches = null;
+      var name = null;
+
+      if (elementProperty) {
+        matches = elementProperty.match(propertyPattern);
+        if (matches) {
+          // Convert to lowercase, and remove any whitespace
+          // so we can match below.
+          name = matches[0].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 = jsonld.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 = jsonld.byline ||
+                      values["dc:creator"] ||
+                      values["dcterm:creator"] ||
+                      values["author"];
+
+    // get description
+    metadata.excerpt = jsonld.excerpt ||
+                       values["dc:description"] ||
+                       values["dcterm:description"] ||
+                       values["og:description"] ||
+                       values["weibo:article:description"] ||
+                       values["weibo:webpage:description"] ||
+                       values["description"] ||
+                       values["twitter:description"];
+
+    // get site name
+    metadata.siteName = jsonld.siteName ||
+                        values["og:site_name"];
+
+    // get article published time
+    metadata.publishedTime = jsonld.datePublished ||
+      values["article:published_time"] || null;
+
+    // in many sites the meta value is escaped with HTML entities,
+    // so here we need to unescape it
+    metadata.title = this._unescapeHtmlEntities(metadata.title);
+    metadata.byline = this._unescapeHtmlEntities(metadata.byline);
+    metadata.excerpt = this._unescapeHtmlEntities(metadata.excerpt);
+    metadata.siteName = this._unescapeHtmlEntities(metadata.siteName);
+    metadata.publishedTime = this._unescapeHtmlEntities(metadata.publishedTime);
+
+    return metadata;
+  },
+
+  /**
+   * Check if node is image, or if node contains exactly only one image
+   * whether as a direct child or as its descendants.
+   *
+   * @param Element
+  **/
+  _isSingleImage: function(node) {
+    if (node.tagName === "IMG") {
+      return true;
+    }
+
+    if (node.children.length !== 1 || node.textContent.trim() !== "") {
+      return false;
+    }
+
+    return this._isSingleImage(node.children[0]);
+  },
+
+  /**
+   * Find all <noscript> that are located after <img> nodes, and which contain only one
+   * <img> element. Replace the first image with the image from inside the <noscript> tag,
+   * and remove the <noscript> tag. This improves the quality of the images we use on
+   * some sites (e.g. Medium).
+   *
+   * @param Element
+  **/
+  _unwrapNoscriptImages: function(doc) {
+    // Find img without source or attributes that might contains image, and remove it.
+    // This is done to prevent a placeholder img is replaced by img from noscript in next step.
+    var imgs = Array.from(doc.getElementsByTagName("img"));
+    this._forEachNode(imgs, function(img) {
+      for (var i = 0; i < img.attributes.length; i++) {
+        var attr = img.attributes[i];
+        switch (attr.name) {
+          case "src":
+          case "srcset":
+          case "data-src":
+          case "data-srcset":
+            return;
+        }
+
+        if (/\.(jpg|jpeg|png|webp)/i.test(attr.value)) {
+          return;
+        }
+      }
+
+      img.parentNode.removeChild(img);
+    });
+
+    // Next find noscript and try to extract its image
+    var noscripts = Array.from(doc.getElementsByTagName("noscript"));
+    this._forEachNode(noscripts, function(noscript) {
+      // Parse content of noscript and make sure it only contains image
+      var tmp = doc.createElement("div");
+      tmp.innerHTML = noscript.innerHTML;
+      if (!this._isSingleImage(tmp)) {
+        return;
+      }
+
+      // If noscript has previous sibling and it only contains image,
+      // replace it with noscript content. However we also keep old
+      // attributes that might contains image.
+      var prevElement = noscript.previousElementSibling;
+      if (prevElement && this._isSingleImage(prevElement)) {
+        var prevImg = prevElement;
+        if (prevImg.tagName !== "IMG") {
+          prevImg = prevElement.getElementsByTagName("img")[0];
+        }
+
+        var newImg = tmp.getElementsByTagName("img")[0];
+        for (var i = 0; i < prevImg.attributes.length; i++) {
+          var attr = prevImg.attributes[i];
+          if (attr.value === "") {
+            continue;
+          }
+
+          if (attr.name === "src" || attr.name === "srcset" || /\.(jpg|jpeg|png|webp)/i.test(attr.value)) {
+            if (newImg.getAttribute(attr.name) === attr.value) {
+              continue;
+            }
+
+            var attrName = attr.name;
+            if (newImg.hasAttribute(attrName)) {
+              attrName = "data-old-" + attrName;
+            }
+
+            newImg.setAttribute(attrName, attr.value);
+          }
+        }
+
+        noscript.parentNode.replaceChild(tmp.firstElementChild, prevElement);
+      }
+    });
+  },
+
+  /**
+   * Removes script tags from the document.
+   *
+   * @param Element
+  **/
+  _removeScripts: function(doc) {
+    this._removeNodes(this._getAllNodesWithTag(doc, ["script", "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) {
+      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.has(node.tagName) ||
+             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;
+    }
+  },
+
+  /**
+   * 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) {
+      var href = linkNode.getAttribute("href");
+      var coefficient = href && this.REGEXPS.hashUrl.test(href) ? 0.3 : 1;
+      linkLength += this._getInnerText(linkNode).length * coefficient;
+    });
+
+    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(this._getAllNodesWithTag(e, [tag]), function(element) {
+      // Allow youtube and vimeo videos through as people usually want to see those.
+      if (isEmbed) {
+        // First, check the elements attributes to see if any of them contain youtube or vimeo
+        for (var i = 0; i < element.attributes.length; i++) {
+          if (this._allowedVideoRegex.test(element.attributes[i].value)) {
+            return false;
+          }
+        }
+
+        // For embed with <object> tag, check inner HTML as well.
+        if (element.tagName === "object" && this._allowedVideoRegex.test(element.innerHTML)) {
+          return false;
+        }
+      }
+
+      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://searchfox.org/mozilla-central/rev/f82d5c549f046cb64ce5602bfd894b7ae807c8f8/accessible/generic/TableAccessible.cpp#19
+   */
+  _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;
+    }
+  },
+
+  /* convert images and figures that have properties like data-src into images that can be loaded without JS */
+  _fixLazyImages: function (root) {
+    this._forEachNode(this._getAllNodesWithTag(root, ["img", "picture", "figure"]), function (elem) {
+      // In some sites (e.g. Kotaku), they put 1px square image as base64 data uri in the src attribute.
+      // So, here we check if the data uri is too short, just might as well remove it.
+      if (elem.src && this.REGEXPS.b64DataUrl.test(elem.src)) {
+        // Make sure it's not SVG, because SVG can have a meaningful image in under 133 bytes.
+        var parts = this.REGEXPS.b64DataUrl.exec(elem.src);
+        if (parts[1] === "image/svg+xml") {
+          return;
+        }
+
+        // Make sure this element has other attributes which contains image.
+        // If it doesn't, then this src is important and shouldn't be removed.
+        var srcCouldBeRemoved = false;
+        for (var i = 0; i < elem.attributes.length; i++) {
+          var attr = elem.attributes[i];
+          if (attr.name === "src") {
+            continue;
+          }
+
+          if (/\.(jpg|jpeg|png|webp)/i.test(attr.value)) {
+            srcCouldBeRemoved = true;
+            break;
+          }
+        }
+
+        // Here we assume if image is less than 100 bytes (or 133B after encoded to base64)
+        // it will be too small, therefore it might be placeholder image.
+        if (srcCouldBeRemoved) {
+          var b64starts = elem.src.search(/base64\s*/i) + 7;
+          var b64length = elem.src.length - b64starts;
+          if (b64length < 133) {
+            elem.removeAttribute("src");
+          }
+        }
+      }
+
+      // also check for "null" to work around https://github.com/jsdom/jsdom/issues/2580
+      if ((elem.src || (elem.srcset && elem.srcset != "null")) && elem.className.toLowerCase().indexOf("lazy") === -1) {
+        return;
+      }
+
+      for (var j = 0; j < elem.attributes.length; j++) {
+        attr = elem.attributes[j];
+        if (attr.name === "src" || attr.name === "srcset" || attr.name === "alt") {
+          continue;
+        }
+        var copyTo = null;
+        if (/\.(jpg|jpeg|png|webp)\s+\d/.test(attr.value)) {
+          copyTo = "srcset";
+        } else if (/^\s*\S+\.(jpg|jpeg|png|webp)\S*\s*$/.test(attr.value)) {
+          copyTo = "src";
+        }
+        if (copyTo) {
+          //if this is an img or picture, set the attribute directly
+          if (elem.tagName === "IMG" || elem.tagName === "PICTURE") {
+            elem.setAttribute(copyTo, attr.value);
+          } else if (elem.tagName === "FIGURE" && !this._getAllNodesWithTag(elem, ["img", "picture"]).length) {
+            //if the item is a <figure> that does not contain an image or picture, create one and place it inside the figure
+            //see the nytimes-3 testcase for an example
+            var img = this._doc.createElement("img");
+            img.setAttribute(copyTo, attr.value);
+            elem.appendChild(img);
+          }
+        }
+      }
+    });
+  },
+
+  _getTextDensity: function(e, tags) {
+    var textLength = this._getInnerText(e, true).length;
+    if (textLength === 0) {
+      return 0;
+    }
+    var childrenLength = 0;
+    var children = this._getAllNodesWithTag(e, tags);
+    this._forEachNode(children, (child) => childrenLength += this._getInnerText(child, true).length);
+    return childrenLength / textLength;
+  },
+
+  /**
+   * 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;
+
+    // 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(this._getAllNodesWithTag(e, [tag]), function(node) {
+      // First check if this node IS data table, in which case don't remove it.
+      var isDataTable = function(t) {
+        return t._readabilityDataTable;
+      };
+
+      var isList = tag === "ul" || tag === "ol";
+      if (!isList) {
+        var listLength = 0;
+        var listNodes = this._getAllNodesWithTag(node, ["ul", "ol"]);
+        this._forEachNode(listNodes, (list) => listLength += this._getInnerText(list).length);
+        isList = listLength / this._getInnerText(node).length > 0.9;
+      }
+
+      if (tag === "table" && isDataTable(node)) {
+        return false;
+      }
+
+      // Next check if we're inside a data table, in which case don't remove it as well.
+      if (this._hasAncestorTag(node, "table", -1, isDataTable)) {
+        return false;
+      }
+
+      if (this._hasAncestorTag(node, "code")) {
+        return false;
+      }
+
+      var weight = this._getClassWeight(node);
+
+      this.log("Cleaning Conditionally", node);
+
+      var contentScore = 0;
+
+      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 headingDensity = this._getTextDensity(node, ["h1", "h2", "h3", "h4", "h5", "h6"]);
+
+        var embedCount = 0;
+        var embeds = this._getAllNodesWithTag(node, ["object", "embed", "iframe"]);
+
+        for (var i = 0; i < embeds.length; i++) {
+          // If this embed has attribute that matches video regex, don't delete it.
+          for (var j = 0; j < embeds[i].attributes.length; j++) {
+            if (this._allowedVideoRegex.test(embeds[i].attributes[j].value)) {
+              return false;
+            }
+          }
+
+          // For embed with <object> tag, check inner HTML as well.
+          if (embeds[i].tagName === "object" && this._allowedVideoRegex.test(embeds[i].innerHTML)) {
+            return false;
+          }
+
+          embedCount++;
+        }
+
+        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 && headingDensity < 0.9 && 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);
+        // Allow simple lists of images to remain in pages
+        if (isList && haveToRemove) {
+          for (var x = 0; x < node.children.length; x++) {
+            let child = node.children[x];
+            // Don't filter in lists with li's that contain more than one child
+            if (child.children.length > 1) {
+              return haveToRemove;
+            }
+          }
+          let li_count = node.getElementsByTagName("li").length;
+          // Only allow the list to remain if every li contains an image
+          if (img == li_count) {
+            return false;
+          }
+        }
+        return haveToRemove;
+      }
+      return false;
+    });
+  },
+
+  /**
+   * Clean out elements that match the specified conditions
+   *
+   * @param Element
+   * @param Function determines whether a node should be removed
+   * @return void
+   **/
+  _cleanMatchedNodes: function(e, filter) {
+    var endOfSearchMarkerNode = this._getNextNode(e, true);
+    var next = this._getNextNode(e);
+    while (next && next != endOfSearchMarkerNode) {
+      if (filter.call(this, next, next.className + " " + next.id)) {
+        next = this._removeAndGetNext(next);
+      } else {
+        next = this._getNextNode(next);
+      }
+    }
+  },
+
+  /**
+   * Clean out spurious headers from an Element.
+   *
+   * @param Element
+   * @return void
+  **/
+  _cleanHeaders: function(e) {
+    let headingNodes = this._getAllNodesWithTag(e, ["h1", "h2"]);
+    this._removeNodes(headingNodes, function(node) {
+      let shouldRemove = this._getClassWeight(node) < 0;
+      if (shouldRemove) {
+        this.log("Removing header with low class weight:", node);
+      }
+      return shouldRemove;
+    });
+  },
+
+  /**
+   * Check if this node is an H1 or H2 element whose content is mostly
+   * the same as the article title.
+   *
+   * @param Element  the node to check.
+   * @return boolean indicating whether this is a title-like header.
+   */
+  _headerDuplicatesTitle: function(node) {
+    if (node.tagName != "H1" && node.tagName != "H2") {
+      return false;
+    }
+    var heading = this._getInnerText(node, false);
+    this.log("Evaluating similarity of header:", heading, this._articleTitle);
+    return this._textSimilarity(this._articleTitle, heading) > 0.75;
+  },
+
+  _flagIsActive: function(flag) {
+    return (this._flags & flag) > 0;
+  },
+
+  _removeFlag: function(flag) {
+    this._flags = this._flags & ~flag;
+  },
+
+  _isProbablyVisible: function(node) {
+    // Have to null-check node.style and node.className.indexOf to deal with SVG and MathML nodes.
+    return (!node.style || node.style.display != "none")
+      && (!node.style || node.style.visibility != "hidden")
+      && !node.hasAttribute("hidden")
+      //check for "fallback-image" so that wikimedia math images are displayed
+      && (!node.hasAttribute("aria-hidden") || node.getAttribute("aria-hidden") != "true" || (node.className && node.className.indexOf && node.className.indexOf("fallback-image") !== -1));
+  },
+
+  /**
+   * 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");
+      }
+    }
+
+    // Unwrap image from noscript
+    this._unwrapNoscriptImages(this._doc);
+
+    // Extract JSON-LD metadata before removing scripts
+    var jsonLd = this._disableJSONLD ? {} : this._getJSONLD(this._doc);
+
+    // Remove script tags from the document.
+    this._removeScripts(this._doc);
+
+    this._prepDocument();
+
+    var metadata = this._getArticleMetadata(jsonLd);
+    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,
+      lang: this._articleLang,
+      content: this._serializer(articleContent),
+      textContent: textContent,
+      length: textContent.length,
+      excerpt: metadata.excerpt,
+      siteName: metadata.siteName || this._articleSiteName,
+      publishedTime: metadata.publishedTime
+    };
+  }
+};
+
+if (typeof module === "object") {
+  /* global module */
+  module.exports = Readability;
+}