This library is a port of the readability.js library that uses cheerio instead of native DOM APIs.

The goals of this port are the following:

• Portability: Most runtimes and Web Workers don't support DOM apis. By using cheerio, we ensure that you can run readability wherever you want. If your goal is to run it in the main thread of the browser, you can stick to the original implementation.
• Performance: For non-native runtimes, we rely in JSDOM to simulate native DOM APIs. JSDOM does a lot besides parsing HTML, and is pretty heavy and slow. cheerio instead is lightweight and fast. Overall, I've experienced that this port performs 6-8x times faster and consumes a lot less memory than the original one. You can even use htmlparser2 if you need more performance.
• Compatibility: In order to avoid using JSOM, you could use readability's JSDOMParser, Happy Dom or Linkedom. I had compatibility problems using those alternative implementations, but cheerio worked flawlesly even with the most broken html documents that you can find on the internet. You even have the option to use htmlparser2 instead of cheerio's default parse5 for less strict parsing.
• Extensability: The original implementation is pretty hard to read and maintain. While I didn't deviate much from it, I tried to modernize the code base a little bit. I hope people can help me out, specially with the _grabArticle gigantic method with nested while loops. I also saw a lot of issues on the repo for top pages that didn't seem taken care of. It is my intention to try to fix those as I move forward.

The implementation aims to be the same and it keeps the same test set to ensure backwards compatibility.

Installation

cheer-reader is available on jsr:

npx jsr add @paoramen/cheer-reader

Basic usage

To parse a document, you must create a new Readability object from a DOM document object, and then call the parse() method. Here's an example:

import { Readability } from 'cheer-reader'

const $ = load('html><div>yo</div></html>')
const article = new Readability($).parse()

API Reference

new Readability($, options)

The options object accepts a number of properties, all optional:

• debug (boolean, default false): whether to enable logging.
• maxElemsToParse (number, default 0 i.e. no limit): the maximum number of elements to parse.
• nbTopCandidates (number, default 5): the number of top candidates to consider when analysing how tight the competition is among candidates.
• charThreshold (number, default 500): the number of characters an article must have in order to return a result.
• classesToPreserve (array): a set of classes to preserve on HTML elements when the keepClasses options is set to false.
• keepClasses (boolean, default false): whether to preserve all classes on HTML elements. When set to false only classes specified in the classesToPreserve array are kept.
• disableJSONLD (boolean, default false): when extracting page metadata, cheer-reader gives precedence to Schema.org fields specified in the JSON-LD format. Set this option to true to skip JSON-LD parsing.
• serializer (function, default $el => $el.html()) controls how the content property returned by the parse() method is produced from the root DOM element. It may be useful to specify the serializer as the identity function ($el => $el) to obtain a cheerio element instead of a string for content if you plan to process it further.
• allowedVideoRegex (RegExp, default undefined ): a regular expression that matches video URLs that should be allowed to be included in the article content. If undefined, the default regex is applied.
• linkDensityModifier (number, default 0): a number that is added to the base link density threshold during the shadiness checks. This can be used to penalize nodes with a high link density or vice versa.

Added options from the original implementation:

• extraction (boolean, default true): Some libraries are only interested on the metadata and don't want to pay the price of a full extraction. When you enable this option the content, textContent, length and excerpt will be null.

parse()

Returns an object containing the following properties:

• title: article title;
• content: HTML string of processed article content;
• textContent: text content of the article, with all the HTML tags removed;
• length: length of an article, in characters;
• excerpt: article description, or short excerpt from the content;
• byline: author metadata;
• dir: content direction;
• siteName: name of the site;
• lang: content language;
• publishedTime: published time;

Security

If you're going to use cheer-reader with untrusted input (whether in HTML or DOM form), we strongly recommend you use a sanitizer library like DOMPurify to avoid script injection when you use the output of cheer-reader. We would also recommend using CSP to add further defense-in-depth restrictions to what you allow the resulting content to do. The Firefox integration of reader mode uses both of these techniques itself. Sanitizing unsafe content out of the input is explicitly not something we aim to do as part of cheer-reader itself - there are other good sanitizer libraries out there, use them!

Contributing

Please see our Contributing document.

License

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.