Awesome
readabilitySAX
a fast and platform independent readability port
About
This is a port of the algorithm used by the Readability bookmarklet to extract relevant pieces of information from websites, using a SAX parser.
The advantage over other ports, e.g. arrix/node-readability, is a smaller memory footprint and a much faster execution. In my tests, most pages, even large ones, were finished within 15ms (on node, see below for more information). It works with Rhino, so it runs on YQL, which may have interesting uses. And it works within a browser.
The Readability extraction algorithm was completely ported, but some adjustments were made:
-
<article>
and<section>
tags are recognized and gain a higher value -
If a heading is part of the pages
<title>
, it is removed (Readability removed any single<h2>
, and ignored other tags) -
henry
andinstapaper-body
are classes to show an algorithm like this where the content is. readabilitySAX recognizes them and adds additional points -
Every bit of code that was taken from the original algorithm was optimized, eg. RegExps should now perform faster (they were optimized & use
RegExp#test
instead ofString#match
, which doesn't force the interpreter to build an array) -
Some improvements made by GGReadability (an Obj-C port of Readability) were adopted
- Images get additional scores when their
height
orwidth
attributes are high - icon sized images (<= 32px) get skipped - Additional classes & ids are checked
- Images get additional scores when their
How To
Install readabilitySAX
npm install readabilitySAX
CLI
A command line interface (CLI) may be installed via
npm install -g readabilitySAX
It's then available via
readability <domain> [<format>]
To get this readme, just run
readability https://github.com/FB55/readabilitySAX
The format is optional (it's either text
or html
, the default value is
text
).
Usage
Node
Just run require("readabilitySAX")
. You'll get an object containing three
methods:
-
Readability(settings)
: The readability constructor. It works as a handler forhtmlparser2
. Read more about it in the wiki! -
WritableStream(settings, cb)
: A constructor that uniteshtmlparser2
and theReadability
constructor. It's a writable stream, so simply.write
all your data to it. Your callback will be called once.end
was called. Bonus: You can also.pipe
data into it! -
createWritableStream(settings, cb)
: Returns a new instance of theWritableStream
. (It's a simple factory method.)
There are two methods available that are deprecated and will be removed in a future version:
-
get(link, [settings], callback)
: Gets a webpage and process it. -
process(data)
: Takes a string, runs readabilitySAX and returns the page.
Please don't use those two methods anymore. Streams are the way you should build interfaces in node, and that's what I want encourage people to use.
Browsers
I started to implement simplified SAX-"parsers" for Rhino/YQL (using E4X) and
the browser (using the DOM) to increase the overall performance on those
platforms. The DOM version is inside the /browsers
dir.
A demo of how to use readabilitySAX inside a browser may be found at
jsFiddle. Some basic example files are
inside the /browsers
directory.
YQL
A table using E4X-based events is available as the community table
redabilitySAX
, as well as
here.
Parsers (on node)
Most SAX parsers (as sax.js) fail when a document is malformed XML, even if it's
correct HTML. readabilitySAX should be used with
htmlparser2, my fork of the htmlparser
-module
(used by eg. jsdom
), which corrects most faults. It's listed as a dependency,
so npm should install it with readabilitySAX.
Performance
Speed
Using a package of 724 pages from CleanEval (their website seems to be down, try to google it), readabilitySAX processed all of them in 5768 ms, that's an average of 7.97 ms per page.
The benchmark was done using tests/benchmark.js
on a MacBook (late 2010) and
is probably far from perfect.
Performance is the main goal of this project. The current speed should be good enough to run readabilitySAX on a singe-threaded web server with an average number of requests. That's an accomplishment!
Accuracy
The main goal of CleanEval is to evaluate the accuracy of an algorithm.
// TODO
Todo
- Add documentation & examples
- Add support for URLs containing hash-bangs (
#!
) - Allow fetching articles with more than one page
- Don't remove all images inside
<a>
tags