gecko-dev/mobile/android/chrome/content/Readability.js

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/*
* Copyright (c) 2010 Arc90 Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This code is heavily based on Arc90's readability.js (1.7.1) script
* available at: http://code.google.com/p/arc90labs-readability
*/
var Readability = function(uri, doc) {
const ENABLE_LOGGING = false;
this._uri = uri;
this._doc = doc;
this._biggestFrame = false;
this._articleByline = null;
this._articleDir = null;
// Start with all flags set
this._flags = this.FLAG_STRIP_UNLIKELYS |
this.FLAG_WEIGHT_CLASSES |
this.FLAG_CLEAN_CONDITIONALLY;
// The list of pages we've parsed in this call of readability,
// for autopaging. As a key store for easier searching.
this._parsedPages = {};
// A list of the ETag headers of pages we've parsed, in case they happen to match,
// we'll know it's a duplicate.
this._pageETags = {};
// Make an AJAX request for each page and append it to the document.
this._curPageNum = 1;
// Control whether log messages are sent to the console
if (ENABLE_LOGGING) {
this.log = function (msg) {
dump("Reader: (Readability) " + msg);
};
} else {
this.log = function () {};
}
}
Readability.prototype = {
FLAG_STRIP_UNLIKELYS: 0x1,
FLAG_WEIGHT_CLASSES: 0x2,
FLAG_CLEAN_CONDITIONALLY: 0x4,
// The number of top candidates to consider when analysing how
// tight the competition is among candidates.
N_TOP_CANDIDATES: 5,
// The maximum number of pages to loop through before we call
// it quits and just show a link.
MAX_PAGES: 5,
// All of the regular expressions in use within readability.
// Defined up here so we don't instantiate them repeatedly in loops.
REGEXPS: {
unlikelyCandidates: /combx|comment|community|disqus|extra|foot|header|menu|remark|rss|shoutbox|sidebar|sponsor|ad-break|agegate|pagination|pager|popup|tweet|twitter/i,
okMaybeItsACandidate: /and|article|body|column|main|shadow/i,
positive: /article|body|content|entry|hentry|main|page|pagination|post|text|blog|story/i,
negative: /hidden|combx|comment|com-|contact|foot|footer|footnote|masthead|media|meta|outbrain|promo|related|scroll|shoutbox|sidebar|sponsor|shopping|tags|tool|widget/i,
extraneous: /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,
byline: /byline|author|dateline|writtenby/i,
replaceFonts: /<(\/?)font[^>]*>/gi,
trim: /^\s+|\s+$/g,
normalize: /\s{2,}/g,
videos: /http:\/\/(www\.)?(youtube|vimeo)\.com/i,
nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
prevLink: /(prev|earl|old|new|<|«)/i,
whitespace: /^\s*$/
},
DIV_TO_P_ELEMS: [ "A", "BLOCKQUOTE", "DL", "DIV", "IMG", "OL", "P", "PRE", "TABLE", "UL", "SELECT" ],
/**
* Run any post-process modifications to article content as necessary.
*
* @param Element
* @return void
**/
_postProcessContent: function(articleContent) {
// Readability cannot open relative uris so we convert them to absolute uris.
this._fixRelativeUris(articleContent);
},
/**
* Converts each <a> and <img> uri in the given element to an absolute URI.
*
* @param Element
* @return void
*/
_fixRelativeUris: function(articleContent) {
let scheme = this._uri.scheme;
let prePath = this._uri.prePath;
let pathBase = this._uri.pathBase;
function toAbsoluteURI(uri) {
// If this is already an absolute URI, return it.
if (/^[a-zA-Z][a-zA-Z0-9\+\-\.]*:/.test(uri))
return uri;
// Scheme-rooted relative URI.
if (uri.substr(0, 2) == "//")
return scheme + "://" + uri.substr(2);
// Prepath-rooted relative URI.
if (uri[0] == "/")
return prePath + uri;
// Standard relative URI; add entire path. pathBase already includes a
// trailing "/".
return pathBase + uri;
}
function convertRelativeURIs(tagName, propName) {
let elems = articleContent.getElementsByTagName(tagName);
for (let i = elems.length; --i >= 0;) {
let elem = elems[i];
let relativeURI = elem.getAttribute(propName);
if (relativeURI != null)
elems[i].setAttribute(propName, toAbsoluteURI(relativeURI));
}
}
// Fix links.
convertRelativeURIs("a", "href");
// Fix images.
convertRelativeURIs("img", "src");
},
/**
* Get the article title as an H1.
*
* @return void
**/
_getArticleTitle: function() {
let doc = this._doc;
let curTitle = "";
let origTitle = "";
try {
curTitle = origTitle = doc.title;
// If they had an element with id "title" in their HTML
if (typeof curTitle !== "string")
curTitle = origTitle = this._getInnerText(doc.getElementsByTagName('title')[0]);
} catch(e) {}
if (curTitle.match(/ [\|\-] /)) {
curTitle = origTitle.replace(/(.*)[\|\-] .*/gi,'$1');
if (curTitle.split(' ').length < 3)
curTitle = origTitle.replace(/[^\|\-]*[\|\-](.*)/gi,'$1');
} else if (curTitle.indexOf(': ') !== -1) {
curTitle = origTitle.replace(/.*:(.*)/gi, '$1');
if (curTitle.split(' ').length < 3)
curTitle = origTitle.replace(/[^:]*[:](.*)/gi,'$1');
} else if (curTitle.length > 150 || curTitle.length < 15) {
let hOnes = doc.getElementsByTagName('h1');
if (hOnes.length === 1)
curTitle = this._getInnerText(hOnes[0]);
}
curTitle = curTitle.replace(this.REGEXPS.trim, "");
if (curTitle.split(' ').length <= 4)
curTitle = origTitle;
return curTitle;
},
/**
* Prepare the HTML document for readability to scrape it.
* This includes things like stripping javascript, CSS, and handling terrible markup.
*
* @return void
**/
_prepDocument: function() {
let doc = this._doc;
// In some cases a body element can't be found (if the HTML is
// totally hosed for example) so we create a new body node and
// append it to the document.
if (doc.body === null) {
let body = doc.createElement("body");
try {
doc.body = body;
} catch(e) {
doc.documentElement.appendChild(body);
this.log(e);
}
}
// Remove all style tags in head
let styleTags = doc.getElementsByTagName("style");
for (let st = 0; st < styleTags.length; st += 1) {
styleTags[st].textContent = "";
}
this._replaceBrs(doc.body);
let fonts = doc.getElementsByTagName("FONT");
for (let i = fonts.length; --i >=0;) {
this._setNodeTag(fonts[i], "SPAN");
}
},
/**
* Finds the next element, starting from the given node, and ignoring
* whitespace in between. If the given node is an element, the same node is
* returned.
*/
_nextElement: function (node) {
let next = node;
while (next
&& (next.nodeType != Node.ELEMENT_NODE)
&& this.REGEXPS.whitespace.test(next.textContent)) {
next = next.nextSibling;
}
return next;
},
/**
* Replaces 2 or more successive <br> elements with a single <p>.
* Whitespace between <br> elements are ignored. For example:
* <div>foo<br>bar<br> <br><br>abc</div>
* will become:
* <div>foo<br>bar<p>abc</p></div>
*/
_replaceBrs: function (elem) {
let brs = elem.getElementsByTagName("br");
for (let i = 0; i < brs.length; i++) {
let br = brs[i];
let next = br.nextSibling;
// Whether 2 or more <br> elements have been found and replaced with a
// <p> block.
let replaced = false;
// If we find a <br> chain, remove the <br>s until we hit another element
// or non-whitespace. This leaves behind the first <br> in the chain
// (which will be replaced with a <p> later).
while ((next = this._nextElement(next)) && (next.tagName == "BR")) {
replaced = true;
let sibling = next.nextSibling;
next.parentNode.removeChild(next);
next = sibling;
}
// If we removed a <br> chain, replace the remaining <br> with a <p>. Add
// all sibling nodes as children of the <p> until we hit another <br>
// chain.
if (replaced) {
let p = this._doc.createElement("p");
br.parentNode.replaceChild(p, br);
next = p.nextSibling;
while (next) {
// If we've hit another <br><br>, we're done adding children to this <p>.
if (next.tagName == "BR") {
let nextElem = this._nextElement(next);
if (nextElem && nextElem.tagName == "BR")
break;
}
// Otherwise, make this node a child of the new <p>.
let sibling = next.nextSibling;
p.appendChild(next);
next = sibling;
}
}
}
},
_setNodeTag: function (node, tag) {
node.localName = tag.toLowerCase();
node.tagName = tag.toUpperCase();
},
/**
* Prepare the article node for display. Clean out any inline styles,
* iframes, forms, strip extraneous <p> tags, etc.
*
* @param Element
* @return void
**/
_prepArticle: function(articleContent) {
this._cleanStyles(articleContent);
// Clean out junk from the article content
this._cleanConditionally(articleContent, "form");
this._clean(articleContent, "object");
this._clean(articleContent, "h1");
// If there is only one h2, they are probably using it as a header
// and not a subheader, so remove it since we already have a header.
if (articleContent.getElementsByTagName('h2').length === 1)
this._clean(articleContent, "h2");
this._clean(articleContent, "iframe");
this._cleanHeaders(articleContent);
// Do these last as the previous stuff may have removed junk
// that will affect these
this._cleanConditionally(articleContent, "table");
this._cleanConditionally(articleContent, "ul");
this._cleanConditionally(articleContent, "div");
// Remove extra paragraphs
let articleParagraphs = articleContent.getElementsByTagName('p');
for (let i = articleParagraphs.length - 1; i >= 0; i -= 1) {
let imgCount = articleParagraphs[i].getElementsByTagName('img').length;
let embedCount = articleParagraphs[i].getElementsByTagName('embed').length;
let objectCount = articleParagraphs[i].getElementsByTagName('object').length;
if (imgCount === 0 &&
embedCount === 0 &&
objectCount === 0 &&
this._getInnerText(articleParagraphs[i], false) === '')
articleParagraphs[i].parentNode.removeChild(articleParagraphs[i]);
}
let brs = articleContent.getElementsByTagName("BR");
for (let i = brs.length; --i >= 0;) {
let br = brs[i];
let next = this._nextElement(br.nextSibling);
if (next && next.tagName == "P")
br.parentNode.removeChild(br);
}
},
/**
* Initialize a node with the readability object. Also checks the
* className/id for special names to add to its score.
*
* @param Element
* @return void
**/
_initializeNode: function(node) {
node.readability = {"contentScore": 0};
switch(node.tagName) {
case 'DIV':
node.readability.contentScore += 5;
break;
case 'PRE':
case 'TD':
case 'BLOCKQUOTE':
node.readability.contentScore += 3;
break;
case 'ADDRESS':
case 'OL':
case 'UL':
case 'DL':
case 'DD':
case 'DT':
case 'LI':
case 'FORM':
node.readability.contentScore -= 3;
break;
case 'H1':
case 'H2':
case 'H3':
case 'H4':
case 'H5':
case 'H6':
case 'TH':
node.readability.contentScore -= 5;
break;
}
node.readability.contentScore += this._getClassWeight(node);
},
/***
* grabArticle - Using a variety of metrics (content score, classname, element types), find the content that is
* most likely to be the stuff a user wants to read. Then return it wrapped up in a div.
*
* @param page a document to run upon. Needs to be a full document, complete with body.
* @return Element
**/
_grabArticle: function (page) {
let doc = this._doc;
let isPaging = (page !== null ? true: false);
page = page ? page : this._doc.body;
let pageCacheHtml = page.innerHTML;
// Check if any "dir" is set on the toplevel document element
this._articleDir = doc.documentElement.getAttribute("dir");
while (true) {
let stripUnlikelyCandidates = this._flagIsActive(this.FLAG_STRIP_UNLIKELYS);
let allElements = page.getElementsByTagName('*');
// First, node prepping. Trash nodes that look cruddy (like ones with the
// class name "comment", etc), and turn divs into P tags where they have been
// used inappropriately (as in, where they contain no other block level elements.)
//
// Note: Assignment from index for performance. See http://www.peachpit.com/articles/article.aspx?p=31567&seqNum=5
// TODO: Shouldn't this be a reverse traversal?
let node = null;
let nodesToScore = [];
// Let each node know its index in the allElements array.
for (let i = allElements.length; --i >= 0;) {
allElements[i]._index = i;
}
/**
* JSDOMParser returns static node lists, not live ones. When we remove
* an element from the document, we need to manually remove it - and all
* of its children - from the allElements array.
*/
function purgeNode(node) {
for (let i = node.childNodes.length; --i >= 0;) {
purgeNode(node.childNodes[i]);
}
if (node._index !== undefined && allElements[node._index] == node)
delete allElements[node._index];
}
for (let nodeIndex = 0; nodeIndex < allElements.length; nodeIndex++) {
if (!(node = allElements[nodeIndex]))
continue;
let matchString = node.className + node.id;
if (matchString.search(this.REGEXPS.byline) !== -1 && !this._articleByline) {
this._articleByline = node.textContent;
node.parentNode.removeChild(node);
purgeNode(node);
continue;
}
// Remove unlikely candidates
if (stripUnlikelyCandidates) {
if (matchString.search(this.REGEXPS.unlikelyCandidates) !== -1 &&
matchString.search(this.REGEXPS.okMaybeItsACandidate) === -1 &&
node.tagName !== "BODY") {
this.log("Removing unlikely candidate - " + matchString);
node.parentNode.removeChild(node);
purgeNode(node);
continue;
}
}
if (node.tagName === "P" || node.tagName === "TD" || node.tagName === "PRE")
nodesToScore[nodesToScore.length] = node;
// Turn all divs that don't have children block level elements into p's
if (node.tagName === "DIV") {
// Sites like http://mobile.slate.com encloses each paragraph with a DIV
// element. DIVs with only a P element inside and no text content can be
// safely converted into plain P elements to avoid confusing the scoring
// algorithm with DIVs with are, in practice, paragraphs.
let pIndex = this._getSinglePIndexInsideDiv(node);
if (pIndex >= 0 || !this._hasChildBlockElement(node)) {
if (pIndex >= 0) {
let newNode = node.childNodes[pIndex];
node.parentNode.replaceChild(newNode, node);
purgeNode(node);
} else {
this._setNodeTag(node, "P");
nodesToScore[nodesToScore.length] = node;
}
} else {
// EXPERIMENTAL
for (let i = 0, il = node.childNodes.length; i < il; i += 1) {
let childNode = node.childNodes[i];
if (!childNode)
continue;
if (childNode.nodeType === 3) { // Node.TEXT_NODE
let p = doc.createElement('p');
p.textContent = childNode.textContent;
p.style.display = 'inline';
p.className = 'readability-styled';
childNode.parentNode.replaceChild(p, childNode);
}
}
}
}
}
/**
* Loop through all paragraphs, and assign a score to them based on how content-y they look.
* Then add their score to their parent node.
*
* A score is determined by things like number of commas, class names, etc. Maybe eventually link density.
**/
let candidates = [];
for (let pt = 0; pt < nodesToScore.length; pt += 1) {
let parentNode = nodesToScore[pt].parentNode;
let grandParentNode = parentNode ? parentNode.parentNode : null;
let innerText = this._getInnerText(nodesToScore[pt]);
if (!parentNode || typeof(parentNode.tagName) === 'undefined')
continue;
// If this paragraph is less than 25 characters, don't even count it.
if (innerText.length < 25)
continue;
// Initialize readability data for the parent.
if (typeof parentNode.readability === 'undefined') {
this._initializeNode(parentNode);
candidates.push(parentNode);
}
// Initialize readability data for the grandparent.
if (grandParentNode &&
typeof(grandParentNode.readability) === 'undefined' &&
typeof(grandParentNode.tagName) !== 'undefined') {
this._initializeNode(grandParentNode);
candidates.push(grandParentNode);
}
let contentScore = 0;
// Add a point for the paragraph itself as a base.
contentScore += 1;
// Add points for any commas within this paragraph.
contentScore += innerText.split(',').length;
// For every 100 characters in this paragraph, add another point. Up to 3 points.
contentScore += Math.min(Math.floor(innerText.length / 100), 3);
// Add the score to the parent. The grandparent gets half.
parentNode.readability.contentScore += contentScore;
if (grandParentNode)
grandParentNode.readability.contentScore += contentScore / 2;
}
// After we've calculated scores, loop through all of the possible
// candidate nodes we found and find the one with the highest score.
let topCandidates = [];
for (let c = 0, cl = candidates.length; c < cl; c += 1) {
let candidate = candidates[c];
// Scale the final candidates score based on link density. Good content
// should have a relatively small link density (5% or less) and be mostly
// unaffected by this operation.
let candidateScore = candidate.readability.contentScore * (1 - this._getLinkDensity(candidate));
candidate.readability.contentScore = candidateScore;
this.log('Candidate: ' + candidate + " (" + candidate.className + ":" +
candidate.id + ") with score " + candidateScore);
for (let t = 0; t < this.N_TOP_CANDIDATES; t++) {
let aTopCandidate = topCandidates[t];
if (!aTopCandidate || candidateScore > aTopCandidate.readability.contentScore) {
topCandidates.splice(t, 0, candidate);
if (topCandidates.length > this.N_TOP_CANDIDATES)
topCandidates.pop();
break;
}
}
}
let topCandidate = topCandidates[0] || null;
let lastTopCandidate = (topCandidates.length > 3 ? topCandidates[topCandidates.length - 1] : null);
// If we still have no top candidate, just use the body as a last resort.
// We also have to copy the body node so it is something we can modify.
if (topCandidate === null || topCandidate.tagName === "BODY") {
// Move all of the page's children into topCandidate
topCandidate = doc.createElement("DIV");
let children = page.childNodes;
for (let i = 0; i < children.length; ++i) {
topCandidate.appendChild(children[i]);
}
page.appendChild(topCandidate);
this._initializeNode(topCandidate);
}
// Now that we have the top candidate, look through its siblings for content
// that might also be related. Things like preambles, content split by ads
// that we removed, etc.
let articleContent = doc.createElement("DIV");
if (isPaging)
articleContent.id = "readability-content";
let siblingScoreThreshold = Math.max(10, topCandidate.readability.contentScore * 0.2);
let siblingNodes = topCandidate.parentNode.childNodes;
for (let s = 0, sl = siblingNodes.length; s < sl; s += 1) {
let siblingNode = siblingNodes[s];
let append = false;
this.log("Looking at sibling node: " + siblingNode + " (" + siblingNode.className + ":" + siblingNode.id + ")" + ((typeof siblingNode.readability !== 'undefined') ? (" with score " + siblingNode.readability.contentScore) : ''));
this.log("Sibling has score " + (siblingNode.readability ? siblingNode.readability.contentScore : 'Unknown'));
if (siblingNode === topCandidate)
append = true;
let contentBonus = 0;
// Give a bonus if sibling nodes and top candidates have the example same classname
if (siblingNode.className === topCandidate.className && topCandidate.className !== "")
contentBonus += topCandidate.readability.contentScore * 0.2;
if (typeof siblingNode.readability !== 'undefined' &&
(siblingNode.readability.contentScore+contentBonus) >= siblingScoreThreshold)
append = true;
if (siblingNode.nodeName === "P") {
let linkDensity = this._getLinkDensity(siblingNode);
let nodeContent = this._getInnerText(siblingNode);
let nodeLength = nodeContent.length;
if (nodeLength > 80 && linkDensity < 0.25) {
append = true;
} else if (nodeLength < 80 && linkDensity === 0 && nodeContent.search(/\.( |$)/) !== -1) {
append = true;
}
}
if (append) {
this.log("Appending node: " + siblingNode);
// siblingNodes is a reference to the childNodes array, and
// siblingNode is removed from the array when we call appendChild()
// below. As a result, we must revisit this index since the nodes
// have been shifted.
s -= 1;
sl -= 1;
if (siblingNode.nodeName !== "DIV" && siblingNode.nodeName !== "P") {
// We have a node that isn't a common block level element, like a form or td tag.
// Turn it into a div so it doesn't get filtered out later by accident. */
this.log("Altering siblingNode of " + siblingNode.nodeName + ' to div.');
this._setNodeTag(siblingNode, "DIV");
}
// To ensure a node does not interfere with readability styles,
// remove its classnames.
siblingNode.className = "";
// Append sibling and subtract from our list because it removes
// the node when you append to another node.
articleContent.appendChild(siblingNode);
}
}
// So we have all of the content that we need. Now we clean it up for presentation.
this._prepArticle(articleContent);
if (this._curPageNum === 1) {
let div = doc.createElement("DIV");
div.id = "readability-page-1";
div.className = "page";
let children = articleContent.childNodes;
for (let i = 0; i < children.length; ++i) {
div.appendChild(children[i]);
}
articleContent.appendChild(div);
}
// Now that we've gone through the full algorithm, check to see if
// we got any meaningful content. If we didn't, we may need to re-run
// grabArticle with different flags set. This gives us a higher likelihood of
// finding the content, and the sieve approach gives us a higher likelihood of
// finding the -right- content.
if (this._getInnerText(articleContent, true).length < 500) {
page.innerHTML = pageCacheHtml;
if (this._flagIsActive(this.FLAG_STRIP_UNLIKELYS)) {
this._removeFlag(this.FLAG_STRIP_UNLIKELYS);
} else if (this._flagIsActive(this.FLAG_WEIGHT_CLASSES)) {
this._removeFlag(this.FLAG_WEIGHT_CLASSES);
} else if (this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY)) {
this._removeFlag(this.FLAG_CLEAN_CONDITIONALLY);
} else {
return null;
}
} else {
if (lastTopCandidate !== null) {
// EXPERIMENTAL: Contrast ratio is how we measure the level of competition between candidates in the
// readability algorithm. This is to avoid offering reader mode on pages that are more like
// a list or directory of links with summaries. It takes the score of the last top candidate
// (see N_TOP_CANDIDATES) and checks how it compares to the top candidate's. On pages that are not
// actual articles, there will likely be many candidates with similar score (i.e. higher contrast ratio).
let contrastRatio = lastTopCandidate.readability.contentScore / topCandidate.readability.contentScore;
if (contrastRatio > 0.45)
return null;
}
return articleContent;
}
}
},
/**
* Removes script tags from the document.
*
* @param Element
**/
_removeScripts: function(doc) {
let scripts = doc.getElementsByTagName('script');
for (let i = scripts.length - 1; i >= 0; i -= 1) {
scripts[i].nodeValue="";
scripts[i].removeAttribute('src');
if (scripts[i].parentNode)
scripts[i].parentNode.removeChild(scripts[i]);
}
},
/**
* Get child index of the only P element inside a DIV with no
* text content. Returns -1 if the DIV node contains non-empty
* text nodes or if it contains other element nodes.
*
* @param Element
**/
_getSinglePIndexInsideDiv: function(e) {
let childNodes = e.childNodes;
let pIndex = -1;
for (let i = childNodes.length; --i >= 0;) {
let node = childNodes[i];
if (node.nodeType === Node.ELEMENT_NODE) {
if (node.tagName !== "P")
return -1;
if (pIndex >= 0)
return -1;
pIndex = i;
} else if (node.nodeType == Node.TEXT_NODE && this._getInnerText(node, false)) {
return -1;
}
}
return pIndex;
},
/**
* Determine whether element has any children block level elements.
*
* @param Element
*/
_hasChildBlockElement: function (e) {
let length = e.childNodes.length;
for (let i = 0; i < length; i++) {
let child = e.childNodes[i];
if (child.nodeType != 1)
continue;
if (this.DIV_TO_P_ELEMS.indexOf(child.tagName) !== -1 || this._hasChildBlockElement(child))
return true;
}
return false;
},
/**
* Get the inner text of a node - cross browser compatibly.
* This also strips out any excess whitespace to be found.
*
* @param Element
* @return string
**/
_getInnerText: function(e, normalizeSpaces) {
let textContent = e.textContent.replace(this.REGEXPS.trim, "");
normalizeSpaces = (typeof normalizeSpaces === 'undefined') ? true : normalizeSpaces;
if (normalizeSpaces) {
return textContent.replace(this.REGEXPS.normalize, " ");
} else {
return textContent;
}
},
/**
* Get the number of times a string s appears in the node e.
*
* @param Element
* @param string - what to split on. Default is ","
* @return number (integer)
**/
_getCharCount: function(e,s) {
s = s || ",";
return this._getInnerText(e).split(s).length - 1;
},
/**
* Remove the style attribute on every e and under.
* TODO: Test if getElementsByTagName(*) is faster.
*
* @param Element
* @return void
**/
_cleanStyles: function(e) {
e = e || this._doc;
let cur = e.firstChild;
if (!e)
return;
// Remove any root styles, if we're able.
if (typeof e.removeAttribute === 'function' && e.className !== 'readability-styled')
e.removeAttribute('style');
// Go until there are no more child nodes
while (cur !== null) {
if (cur.nodeType === 1) {
// Remove style attribute(s) :
if (cur.className !== "readability-styled")
cur.removeAttribute("style");
this._cleanStyles(cur);
}
cur = cur.nextSibling;
}
},
/**
* Get the density of links as a percentage of the content
* This is the amount of text that is inside a link divided by the total text in the node.
*
* @param Element
* @return number (float)
**/
_getLinkDensity: function(e) {
let links = e.getElementsByTagName("a");
let textLength = this._getInnerText(e).length;
let linkLength = 0;
for (let i = 0, il = links.length; i < il; i += 1) {
linkLength += this._getInnerText(links[i]).length;
}
return linkLength / textLength;
},
/**
* Find a cleaned up version of the current URL, to use for comparing links for possible next-pageyness.
*
* @author Dan Lacy
* @return string the base url
**/
_findBaseUrl: function() {
let uri = this._uri;
let noUrlParams = uri.path.split("?")[0];
let urlSlashes = noUrlParams.split("/").reverse();
let cleanedSegments = [];
let possibleType = "";
for (let i = 0, slashLen = urlSlashes.length; i < slashLen; i += 1) {
let segment = urlSlashes[i];
// Split off and save anything that looks like a file type.
if (segment.indexOf(".") !== -1) {
possibleType = segment.split(".")[1];
// If the type isn't alpha-only, it's probably not actually a file extension.
if (!possibleType.match(/[^a-zA-Z]/))
segment = segment.split(".")[0];
}
// EW-CMS specific segment replacement. Ugly.
// Example: http://www.ew.com/ew/article/0,,20313460_20369436,00.html
if (segment.indexOf(',00') !== -1)
segment = segment.replace(',00', '');
// If our first or second segment has anything looking like a page number, remove it.
if (segment.match(/((_|-)?p[a-z]*|(_|-))[0-9]{1,2}$/i) && ((i === 1) || (i === 0)))
segment = segment.replace(/((_|-)?p[a-z]*|(_|-))[0-9]{1,2}$/i, "");
let del = false;
// If this is purely a number, and it's the first or second segment,
// it's probably a page number. Remove it.
if (i < 2 && segment.match(/^\d{1,2}$/))
del = true;
// If this is the first segment and it's just "index", remove it.
if (i === 0 && segment.toLowerCase() === "index")
del = true;
// If our first or second segment is smaller than 3 characters,
// and the first segment was purely alphas, remove it.
if (i < 2 && segment.length < 3 && !urlSlashes[0].match(/[a-z]/i))
del = true;
// If it's not marked for deletion, push it to cleanedSegments.
if (!del)
cleanedSegments.push(segment);
}
// This is our final, cleaned, base article URL.
return uri.scheme + "://" + uri.host + cleanedSegments.reverse().join("/");
},
/**
* Look for any paging links that may occur within the document.
*
* @param body
* @return object (array)
**/
_findNextPageLink: function(elem) {
let uri = this._uri;
let possiblePages = {};
let allLinks = elem.getElementsByTagName('a');
let articleBaseUrl = this._findBaseUrl();
// Loop through all links, looking for hints that they may be next-page links.
// Things like having "page" in their textContent, className or id, or being a child
// of a node with a page-y className or id.
//
// Also possible: levenshtein distance? longest common subsequence?
//
// After we do that, assign each page a score, and
for (let i = 0, il = allLinks.length; i < il; i += 1) {
let link = allLinks[i];
let linkHref = allLinks[i].href.replace(/#.*$/, '').replace(/\/$/, '');
// If we've already seen this page, ignore it.
if (linkHref === "" ||
linkHref === articleBaseUrl ||
linkHref === uri.spec ||
linkHref in this._parsedPages) {
continue;
}
// If it's on a different domain, skip it.
if (uri.host !== linkHref.split(/\/+/g)[1])
continue;
let linkText = this._getInnerText(link);
// If the linkText looks like it's not the next page, skip it.
if (linkText.match(this.REGEXPS.extraneous) || linkText.length > 25)
continue;
// If the leftovers of the URL after removing the base URL don't contain
// any digits, it's certainly not a next page link.
let linkHrefLeftover = linkHref.replace(articleBaseUrl, '');
if (!linkHrefLeftover.match(/\d/))
continue;
if (!(linkHref in possiblePages)) {
possiblePages[linkHref] = {"score": 0, "linkText": linkText, "href": linkHref};
} else {
possiblePages[linkHref].linkText += ' | ' + linkText;
}
let linkObj = possiblePages[linkHref];
// If the articleBaseUrl isn't part of this URL, penalize this link. It could
// still be the link, but the odds are lower.
// Example: http://www.actionscript.org/resources/articles/745/1/JavaScript-and-VBScript-Injection-in-ActionScript-3/Page1.html
if (linkHref.indexOf(articleBaseUrl) !== 0)
linkObj.score -= 25;
let linkData = linkText + ' ' + link.className + ' ' + link.id;
if (linkData.match(this.REGEXPS.nextLink))
linkObj.score += 50;
if (linkData.match(/pag(e|ing|inat)/i))
linkObj.score += 25;
if (linkData.match(/(first|last)/i)) {
// -65 is enough to negate any bonuses gotten from a > or » in the text,
// If we already matched on "next", last is probably fine.
// If we didn't, then it's bad. Penalize.
if (!linkObj.linkText.match(this.REGEXPS.nextLink))
linkObj.score -= 65;
}
if (linkData.match(this.REGEXPS.negative) || linkData.match(this.REGEXPS.extraneous))
linkObj.score -= 50;
if (linkData.match(this.REGEXPS.prevLink))
linkObj.score -= 200;
// If a parentNode contains page or paging or paginat
let parentNode = link.parentNode;
let positiveNodeMatch = false;
let negativeNodeMatch = false;
while (parentNode) {
let parentNodeClassAndId = parentNode.className + ' ' + parentNode.id;
if (!positiveNodeMatch && parentNodeClassAndId && parentNodeClassAndId.match(/pag(e|ing|inat)/i)) {
positiveNodeMatch = true;
linkObj.score += 25;
}
if (!negativeNodeMatch && parentNodeClassAndId && parentNodeClassAndId.match(this.REGEXPS.negative)) {
// If this is just something like "footer", give it a negative.
// If it's something like "body-and-footer", leave it be.
if (!parentNodeClassAndId.match(this.REGEXPS.positive)) {
linkObj.score -= 25;
negativeNodeMatch = true;
}
}
parentNode = parentNode.parentNode;
}
// If the URL looks like it has paging in it, add to the score.
// Things like /page/2/, /pagenum/2, ?p=3, ?page=11, ?pagination=34
if (linkHref.match(/p(a|g|ag)?(e|ing|ination)?(=|\/)[0-9]{1,2}/i) || linkHref.match(/(page|paging)/i))
linkObj.score += 25;
// If the URL contains negative values, give a slight decrease.
if (linkHref.match(this.REGEXPS.extraneous))
linkObj.score -= 15;
/**
* Minor punishment to anything that doesn't match our current URL.
* NOTE: I'm finding this to cause more harm than good where something is exactly 50 points.
* Dan, can you show me a counterexample where this is necessary?
* if (linkHref.indexOf(window.location.href) !== 0) {
* linkObj.score -= 1;
* }
**/
// If the link text can be parsed as a number, give it a minor bonus, with a slight
// bias towards lower numbered pages. This is so that pages that might not have 'next'
// in their text can still get scored, and sorted properly by score.
let linkTextAsNumber = parseInt(linkText, 10);
if (linkTextAsNumber) {
// Punish 1 since we're either already there, or it's probably
// before what we want anyways.
if (linkTextAsNumber === 1) {
linkObj.score -= 10;
} else {
linkObj.score += Math.max(0, 10 - linkTextAsNumber);
}
}
}
// Loop thrugh all of our possible pages from above and find our top
// candidate for the next page URL. Require at least a score of 50, which
// is a relatively high confidence that this page is the next link.
let topPage = null;
for (let page in possiblePages) {
if (possiblePages.hasOwnProperty(page)) {
if (possiblePages[page].score >= 50 &&
(!topPage || topPage.score < possiblePages[page].score))
topPage = possiblePages[page];
}
}
if (topPage) {
let nextHref = topPage.href.replace(/\/$/,'');
this.log('NEXT PAGE IS ' + nextHref);
this._parsedPages[nextHref] = true;
return nextHref;
} else {
return null;
}
},
_successfulRequest: function(request) {
return (request.status >= 200 && request.status < 300) ||
request.status === 304 ||
(request.status === 0 && request.responseText);
},
_ajax: function(url, options) {
let request = new XMLHttpRequest();
function respondToReadyState(readyState) {
if (request.readyState === 4) {
if (this._successfulRequest(request)) {
if (options.success)
options.success(request);
} else {
if (options.error)
options.error(request);
}
}
}
if (typeof options === 'undefined')
options = {};
request.onreadystatechange = respondToReadyState;
request.open('get', url, true);
request.setRequestHeader('Accept', 'text/html');
try {
request.send(options.postBody);
} catch (e) {
if (options.error)
options.error();
}
return request;
},
_appendNextPage: function(nextPageLink) {
let doc = this._doc;
this._curPageNum += 1;
let articlePage = doc.createElement("DIV");
articlePage.id = 'readability-page-' + this._curPageNum;
articlePage.className = 'page';
articlePage.innerHTML = '<p class="page-separator" title="Page ' + this._curPageNum + '">&sect;</p>';
doc.getElementById("readability-content").appendChild(articlePage);
if (this._curPageNum > this.MAX_PAGES) {
let nextPageMarkup = "<div style='text-align: center'><a href='" + nextPageLink + "'>View Next Page</a></div>";
articlePage.innerHTML = articlePage.innerHTML + nextPageMarkup;
return;
}
// Now that we've built the article page DOM element, get the page content
// asynchronously and load the cleaned content into the div we created for it.
(function(pageUrl, thisPage) {
this._ajax(pageUrl, {
success: function(r) {
// First, check to see if we have a matching ETag in headers - if we do, this is a duplicate page.
let eTag = r.getResponseHeader('ETag');
if (eTag) {
if (eTag in this._pageETags) {
this.log("Exact duplicate page found via ETag. Aborting.");
articlePage.style.display = 'none';
return;
} else {
this._pageETags[eTag] = 1;
}
}
// TODO: this ends up doubling up page numbers on NYTimes articles. Need to generically parse those away.
let page = doc.createElement("DIV");
// Do some preprocessing to our HTML to make it ready for appending.
// - Remove any script tags. Swap and reswap newlines with a unicode
// character because multiline regex doesn't work in javascript.
// - Turn any noscript tags into divs so that we can parse them. This
// allows us to find any next page links hidden via javascript.
// - Turn all double br's into p's - was handled by prepDocument in the original view.
// Maybe in the future abstract out prepDocument to work for both the original document
// and AJAX-added pages.
let responseHtml = r.responseText.replace(/\n/g,'\uffff').replace(/<script.*?>.*?<\/script>/gi, '');
responseHtml = responseHtml.replace(/\n/g,'\uffff').replace(/<script.*?>.*?<\/script>/gi, '');
responseHtml = responseHtml.replace(/\uffff/g,'\n').replace(/<(\/?)noscript/gi, '<$1div');
responseHtml = responseHtml.replace(this.REGEXPS.replaceFonts, '<$1span>');
page.innerHTML = responseHtml;
this._replaceBrs(page);
// Reset all flags for the next page, as they will search through it and
// disable as necessary at the end of grabArticle.
this._flags = 0x1 | 0x2 | 0x4;
let nextPageLink = this._findNextPageLink(page);
// NOTE: if we end up supporting _appendNextPage(), we'll need to
// change this call to be async
let content = this._grabArticle(page);
if (!content) {
this.log("No content found in page to append. Aborting.");
return;
}
// Anti-duplicate mechanism. Essentially, get the first paragraph of our new page.
// Compare it against all of the the previous document's we've gotten. If the previous
// document contains exactly the innerHTML of this first paragraph, it's probably a duplicate.
let firstP = content.getElementsByTagName("P").length ? content.getElementsByTagName("P")[0] : null;
if (firstP && firstP.innerHTML.length > 100) {
for (let i = 1; i <= this._curPageNum; i += 1) {
let rPage = doc.getElementById('readability-page-' + i);
if (rPage && rPage.innerHTML.indexOf(firstP.innerHTML) !== -1) {
this.log('Duplicate of page ' + i + ' - skipping.');
articlePage.style.display = 'none';
this._parsedPages[pageUrl] = true;
return;
}
}
}
this._removeScripts(content);
thisPage.innerHTML = thisPage.innerHTML + content.innerHTML;
// After the page has rendered, post process the content. This delay is necessary because,
// in webkit at least, offsetWidth is not set in time to determine image width. We have to
// wait a little bit for reflow to finish before we can fix floating images.
setTimeout((function() {
this._postProcessContent(thisPage);
}).bind(this), 500);
if (nextPageLink)
this._appendNextPage(nextPageLink);
}
});
}).bind(this)(nextPageLink, articlePage);
},
/**
* Get an elements class/id weight. Uses regular expressions to tell if this
* element looks good or bad.
*
* @param Element
* @return number (Integer)
**/
_getClassWeight: function(e) {
if (!this._flagIsActive(this.FLAG_WEIGHT_CLASSES))
return 0;
let weight = 0;
// Look for a special classname
if (typeof(e.className) === 'string' && e.className !== '') {
if (e.className.search(this.REGEXPS.negative) !== -1)
weight -= 25;
if (e.className.search(this.REGEXPS.positive) !== -1)
weight += 25;
}
// Look for a special ID
if (typeof(e.id) === 'string' && e.id !== '') {
if (e.id.search(this.REGEXPS.negative) !== -1)
weight -= 25;
if (e.id.search(this.REGEXPS.positive) !== -1)
weight += 25;
}
return weight;
},
/**
* Clean a node of all elements of type "tag".
* (Unless it's a youtube/vimeo video. People love movies.)
*
* @param Element
* @param string tag to clean
* @return void
**/
_clean: function(e, tag) {
let targetList = e.getElementsByTagName(tag);
let isEmbed = (tag === 'object' || tag === 'embed');
for (let y = targetList.length - 1; y >= 0; y -= 1) {
// Allow youtube and vimeo videos through as people usually want to see those.
if (isEmbed) {
let attributeValues = "";
for (let i = 0, il = targetList[y].attributes.length; i < il; i += 1) {
attributeValues += targetList[y].attributes[i].value + '|';
}
// First, check the elements attributes to see if any of them contain youtube or vimeo
if (attributeValues.search(this.REGEXPS.videos) !== -1)
continue;
// Then check the elements inside this element for the same.
if (targetList[y].innerHTML.search(this.REGEXPS.videos) !== -1)
continue;
}
targetList[y].parentNode.removeChild(targetList[y]);
}
},
/**
* Clean an element of all tags of type "tag" if they look fishy.
* "Fishy" is an algorithm based on content length, classnames, link density, number of images & embeds, etc.
*
* @return void
**/
_cleanConditionally: function(e, tag) {
if (!this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY))
return;
let tagsList = e.getElementsByTagName(tag);
let curTagsLength = tagsList.length;
// Gather counts for other typical elements embedded within.
// Traverse backwards so we can remove nodes at the same time
// without effecting the traversal.
//
// TODO: Consider taking into account original contentScore here.
for (let i = curTagsLength-1; i >= 0; i -= 1) {
let weight = this._getClassWeight(tagsList[i]);
let contentScore = 0;
this.log("Cleaning Conditionally " + tagsList[i] + " (" + tagsList[i].className + ":" + tagsList[i].id + ")");
if (weight + contentScore < 0) {
tagsList[i].parentNode.removeChild(tagsList[i]);
} else if (this._getCharCount(tagsList[i],',') < 10) {
// If there are not very many commas, and the number of
// non-paragraph elements is more than paragraphs or other
// ominous signs, remove the element.
let p = tagsList[i].getElementsByTagName("p").length;
let img = tagsList[i].getElementsByTagName("img").length;
let li = tagsList[i].getElementsByTagName("li").length-100;
let input = tagsList[i].getElementsByTagName("input").length;
let embedCount = 0;
let embeds = tagsList[i].getElementsByTagName("embed");
for (let ei = 0, il = embeds.length; ei < il; ei += 1) {
if (embeds[ei].src.search(this.REGEXPS.videos) === -1)
embedCount += 1;
}
let linkDensity = this._getLinkDensity(tagsList[i]);
let contentLength = this._getInnerText(tagsList[i]).length;
let toRemove = false;
if (img > p) {
toRemove = true;
} else if (li > p && tag !== "ul" && tag !== "ol") {
toRemove = true;
} else if ( input > Math.floor(p/3) ) {
toRemove = true;
} else if (contentLength < 25 && (img === 0 || img > 2) ) {
toRemove = true;
} else if (weight < 25 && linkDensity > 0.2) {
toRemove = true;
} else if (weight >= 25 && linkDensity > 0.5) {
toRemove = true;
} else if ((embedCount === 1 && contentLength < 75) || embedCount > 1) {
toRemove = true;
}
if (toRemove)
tagsList[i].parentNode.removeChild(tagsList[i]);
}
}
},
/**
* Clean out spurious headers from an Element. Checks things like classnames and link density.
*
* @param Element
* @return void
**/
_cleanHeaders: function(e) {
for (let headerIndex = 1; headerIndex < 3; headerIndex += 1) {
let headers = e.getElementsByTagName('h' + headerIndex);
for (let i = headers.length - 1; i >= 0; i -= 1) {
if (this._getClassWeight(headers[i]) < 0 || this._getLinkDensity(headers[i]) > 0.33)
headers[i].parentNode.removeChild(headers[i]);
}
}
},
_flagIsActive: function(flag) {
return (this._flags & flag) > 0;
},
_addFlag: function(flag) {
this._flags = this._flags | flag;
},
_removeFlag: function(flag) {
this._flags = this._flags & ~flag;
},
/**
* Runs readability.
*
* Workflow:
* 1. Prep the document by removing script tags, css, etc.
* 2. Build readability's DOM tree.
* 3. Grab the article content from the current dom tree.
* 4. Replace the current DOM tree with the new one.
* 5. Read peacefully.
*
* @return void
**/
parse: function () {
// Remove script tags from the document.
this._removeScripts(this._doc);
// FIXME: Disabled multi-page article support for now as it
// needs more work on infrastructure.
// Make sure this document is added to the list of parsed pages first,
// so we don't double up on the first page.
// this._parsedPages[uri.spec.replace(/\/$/, '')] = true;
// Pull out any possible next page link first.
// let nextPageLink = this._findNextPageLink(doc.body);
this._prepDocument();
let articleTitle = this._getArticleTitle();
let articleContent = this._grabArticle();
if (!articleContent)
return null;
this._postProcessContent(articleContent);
// if (nextPageLink) {
// // Append any additional pages after a small timeout so that people
// // can start reading without having to wait for this to finish processing.
// setTimeout((function() {
// this._appendNextPage(nextPageLink);
// }).bind(this), 500);
// }
return { title: articleTitle,
byline: this._articleByline,
dir: this._articleDir,
content: articleContent.innerHTML };
}
};