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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 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;
}
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