100 lines
3.3 KiB
JavaScript
100 lines
3.3 KiB
JavaScript
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/* eslint-env es6:false */
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/*
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* Copyright (c) 2010 Arc90 Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* This code is heavily based on Arc90's readability.js (1.7.1) script
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* available at: http://code.google.com/p/arc90labs-readability
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*/
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var REGEXPS = {
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// NOTE: These two regular expressions are duplicated in
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// Readability.js. Please keep both copies in sync.
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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,
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okMaybeItsACandidate: /and|article|body|column|content|main|shadow/i,
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};
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function isNodeVisible(node) {
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// Have to null-check node.style and node.className.indexOf to deal with SVG and MathML nodes.
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return (!node.style || node.style.display != "none")
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&& !node.hasAttribute("hidden")
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//check for "fallback-image" so that wikimedia math images are displayed
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&& (!node.hasAttribute("aria-hidden") || node.getAttribute("aria-hidden") != "true" || (node.className && node.className.indexOf && node.className.indexOf("fallback-image") !== -1));
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}
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/**
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* Decides whether or not the document is reader-able without parsing the whole thing.
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*
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* @return boolean Whether or not we suspect Readability.parse() will suceeed at returning an article object.
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*/
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function isProbablyReaderable(doc, isVisible) {
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if (!isVisible) {
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isVisible = isNodeVisible;
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}
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var nodes = doc.querySelectorAll("p, pre");
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// Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
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// Some articles' DOM structures might look like
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// <div>
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// Sentences<br>
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// <br>
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// Sentences<br>
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// </div>
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var brNodes = doc.querySelectorAll("div > br");
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if (brNodes.length) {
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var set = new Set(nodes);
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[].forEach.call(brNodes, function(node) {
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set.add(node.parentNode);
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});
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nodes = Array.from(set);
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}
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var score = 0;
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// This is a little cheeky, we use the accumulator 'score' to decide what to return from
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// this callback:
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return [].some.call(nodes, function(node) {
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if (!isVisible(node))
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return false;
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var matchString = node.className + " " + node.id;
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if (REGEXPS.unlikelyCandidates.test(matchString) &&
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!REGEXPS.okMaybeItsACandidate.test(matchString)) {
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return false;
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}
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if (node.matches("li p")) {
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return false;
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}
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var textContentLength = node.textContent.trim().length;
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if (textContentLength < 140) {
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return false;
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}
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score += Math.sqrt(textContentLength - 140);
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if (score > 20) {
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return true;
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}
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return false;
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});
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}
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if (typeof module === "object") {
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module.exports = isProbablyReaderable;
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}
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