Clone this repo:
  1. b3fde16 Allow the word threshold parameter to be configurable by Iqbal Ahmed · 5 weeks ago master
  2. b7c32fe Remove presentational HTML attributes (#385) by Taylor Hunt · 2 months ago
  3. 6f0bd81 Provide more useful output when attributes mismatch, r=me,test-only by Gijs Kruitbosch · 2 months ago
  4. c387d12 Fix eslint issue by unpacking ternary into a proper if statement by Gijs Kruitbosch · 3 months ago
  5. bfd1452 Update eslint to try to fix issues on infra by Gijs · 3 months ago


Build Status

A standalone version of the readability library used for Firefox Reader View. Any changes to Readability.js itself should be reviewed by an appropriate Firefox/toolkit peer, such as @gijsk, since these changes will be automatically merged to mozilla-central.


For outstanding issues, see the issue list in this repo, as well as this bug list.

To test local changes to Readability.js, you can use the automated tests. There's a node script to help you create new ones.

Note that because JSDOMParser is restricted to parsing XHTML-compatible input, you will likely need to tweak any input you fetch directly from the internet (e.g. to close <meta> tags). Even if creating a ‘readable’ version fails, the script will leave the input for you to change. You can then re-run the generate-testcase.js script passing only the test page slug, and it will reuse the altered input. Ideally we should fix the generate-testcase.js script to no longer need this manual pre/post-processing. If you have time to help with this, a pull request would be very welcome!

Please make sure to run eslint against any proposed changes when creating a pull request.


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

var loc = document.location;
var uri = {
  spec: loc.href,
  prePath: loc.protocol + "//" +,
  scheme: loc.protocol.substr(0, loc.protocol.indexOf(":")),
  pathBase: loc.protocol + "//" + + loc.pathname.substr(0, loc.pathname.lastIndexOf("/") + 1)
var article = new Readability(uri, document).parse();

This article object will contain the following properties:

  • uri: original uri object that was passed to constructor
  • title: article title
  • content: HTML string of processed article content
  • length: length of article, in characters
  • excerpt: article description, or short excerpt from content
  • byline: author metadata
  • dir: content direction

If you're using Readability on the web, you will likely be able to use a document reference from elsewhere (e.g. fetched via XMLHttpRequest, in a same-origin <iframe> you have access to, etc.). Otherwise, you would need to construct such an object using a DOM parser such as jsdom. While this repository contains a parser of its own (JSDOMParser), that is restricted to reading XML-compatible markup and therefore we do not recommend it for general use.


Readability's parse() works by modifying the DOM. This removes some elements in the web page. You could avoid this by passing the clone of the document object while creating a Readability object.

var documentClone = document.cloneNode(true); 
var article = new Readability(uri, documentClone).parse();   


Please run eslint as a first check that your changes adhere to our style guidelines.

To run the test suite:

$ mocha test/test-*.js

To run a specific test page by its name:

$ mocha test/test-*.js -g 001

To run the test suite in TDD mode:

$ mocha test/test-*.js -w

Combo time:

$ mocha test/test-*.js -w -g 001


Benchmarks for all test pages:

$ npm run perf

Reference benchmark:

$ npm run perf-reference


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

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.