README - nokogiri-1.10.3 Documentation

# Nokogiri¶ ↑

## Description¶ ↑

Nokogiri (鋸) is an HTML, XML, SAX, and Reader parser. Among Nokogiri's many features is the ability to search documents via XPath or CSS3 selectors.

## Links¶ ↑

- nokogiri.org

- Installation Help

- Tutorials

- Cheat Sheet

- GitHub

- Mailing List

- Chat/Gitter

## Status¶ ↑

## Features¶ ↑

- XML/HTML DOM parser which handles broken HTML

- XML/HTML SAX parser

- XML/HTML Push parser

- XPath 1.0 support for document searching

- CSS3 selector support for document searching

- XML/HTML builder

- XSLT transformer

Nokogiri parses and searches XML/HTML using native libraries (either C or Java, depending on your Ruby), which means it's fast and standards-compliant.

## Installation¶ ↑

If this doesn't work:

    gem install nokogiri

then please start troubleshooting here:

> nokogiri.org/tutorials/installing_nokogiri.html

There are currently 1,237 Stack Overflow questions about Nokogiri installation. The vast majority of them are out of date and therefore incorrect. Please do not use Stack Overflow.

Instead, tell us when the above instructions don't work for you. This allows us to both help you directly and improve the documentation.

### Binary packages¶ ↑

Binary packages are available for some distributions.

- Debian: packages.debian.org/sid/ruby-nokogiri

- SuSE: download.opensuse.org/repositories/devel:/languages:/ruby:/extensions/

- Fedora: s390.koji.fedoraproject.org/koji/packageinfo?packageID=6756

## Support¶ ↑

All official documentation is posted at nokogiri.org (the source for which is at github.com/sparklemotion/nokogiri.org/, and we welcome contributions).

- The Nokogiri mailing list is active: groups.google.com/group/nokogiri-talk

- The Nokogiri bug tracker is here: github.com/sparklemotion/nokogiri/issues

- Before filing a bug report, please read our submission guidelines: nokogiri.org/tutorials/getting_help.html

- The IRC channel is `#nokogiri` on freenode.

- The project's GitHub wiki has an excellent community-maintained Cheat Sheet which might be useful.

Consider subscribing to Tidelift which provides license assurances and timely security notifications for your open source dependencies, including Nokogiri. Tidelift subscriptions also help the Nokogiri maintainers fund our automated testing which in turn allows us to ship releases, bugfixes, and security updates more often.

## Security and Vulnerability Reporting¶ ↑

Please report vulnerabilities at hackerone.com/nokogiri

Full information and description of our security policy is in SECURITY.md

## Synopsis¶ ↑

Nokogiri is a large library, but here is example usage for parsing and examining a document:

    #! /usr/bin/env ruby

    require 'nokogiri'
    require 'open-uri'

    # Fetch and parse HTML document
    doc = Nokogiri::HTML(open('https://nokogiri.org/tutorials/installing_nokogiri.html'))

    puts "### Search for nodes by css"
    doc.css('nav ul.menu li a', 'article h2').each do |link|
      puts link.content
    end

    puts "### Search for nodes by xpath"
    doc.xpath('//nav//ul//li/a', '//article//h2').each do |link|
      puts link.content
    end

    puts "### Or mix and match."
    doc.search('nav ul.menu li a', '//article//h2').each do |link|
      puts link.content
    end

## Requirements¶ ↑

- Ruby 2.3.0 or higher, including any development packages necessary to compile native extensions.

- In Nokogiri 1.6.0 and later libxml2 and libxslt are bundled with the gem, but if you want to use the system versions:

- First, check out the long list of fixes and changes between releases before deciding to use any version older than is bundled with Nokogiri.

- At install time, set the environment variable `NOKOGIRI_USE_SYSTEM_LIBRARIES` or else use the `--use-system-libraries` argument. (See nokogiri.org/tutorials/installing_nokogiri.html#install-with-system-libraries for specifics.)

- libxml2 >=2.6.21 with iconv support (libxml2-dev/-devel is also required)

- libxslt, built with and supported by the given libxml2 (libxslt-dev/-devel is also required)

## Encoding¶ ↑

Strings are always stored as UTF-8 internally. Methods that return text values will always return UTF-8 encoded strings. Methods that return a string containing markup (like `to_xml`, `to_html` and `inner_html`) will return a string encoded like the source document.

WARNING

Some documents declare one encoding, but actually use a different one. In these cases, which encoding should the parser choose?

Data is just a stream of bytes. Humans add meaning to that stream. Any particular set of bytes could be valid characters in multiple encodings, so detecting encoding with 100% accuracy is not possible. `libxml2` does its best, but it can't be right all the time.

If you want Nokogiri to handle the document encoding properly, your best bet is to explicitly set the encoding. Here is an example of explicitly setting the encoding to EUC-JP on the parser:

    doc = Nokogiri.XML('<foo><bar /></foo>', nil, 'EUC-JP')

## Development¶ ↑

    bundle install
      bundle exec rake compile test

## Code of Conduct¶ ↑

We've adopted the Contributor Covenant code of conduct, which you can read in full in CODE_OF_CONDUCT.md.

## License¶ ↑

This project is licensed under the terms of the MIT license.

See this license at LICENSE.md.