We use this library on GitHub when rendering your README or any other rich text file.

The following markups are supported. The dependencies listed are required if you wish to run the library. You can also run script/bootstrap to fetch them all.

• .markdown, .mdown, .mkdn, .md -- gem install redcarpet (https://github.com/vmg/redcarpet)
• .textile -- gem install RedCloth
• .rdoc -- gem install rdoc -v 3.6.1
• .org -- gem install org-ruby
• .creole -- gem install creole
• .mediawiki, .wiki -- gem install wikicloth
• .rst -- easy_install docutils
• .asciidoc, .adoc, .asc -- gem install asciidoctor (https://asciidoctor.org)
• .pod -- Pod::Simple::HTML comes with Perl >= 5.10. Lower versions should install Pod::Simple from CPAN.

gem install github-markup

require 'github/markup'
GitHub::Markup.render('README.markdown', "* One\n* Two")

Or, more realistically:

require 'github/markup'
GitHub::Markup.render(file, File.read(file))

HTML rendered by the various markup language processors gets passed through an HTML sanitization filter for security reasons. HTML elements not in the whitelist are removed. HTML attributes not in the whitelist are removed from the preserved elements.

The following HTML elements, organized by category, are whitelisted:

• Headings: h1, h2, h3, h4, h5, h6, h7, h8
• Prose: p, div, blockquote
• Preformatted: pre
• Inline: b, i, strong, em, tt, code, ins, del, sup, sub, kbd, samp, q, var
• Lists: ol, ul, li, dl, dt, dd
• Tables: table, thead, tbody, tfoot, tr, td, th
• Breaks: br, hr
• Ruby (East Asian): ruby, rt, rp

The following attributes, organized by element, are whitelisted:

• a: href (https://, https://, mailto:https://, github-windows:https:// and github-mac:https:// URI schemes and relative paths only)
• img: src (https:// and https::https:// URI schemes and relative paths only)
• div: itemscope, itemtype
• all: abbr, accept, accept-charset, accesskey, action, align, alt, axis, border, cellpadding, cellspacing, char, charoff, charset, checked, cite, clear, cols, colspan, color, compact, coords, datetime, dir, disabled, enctype, for, frame, headers, height, hreflang, hspace, ismap, label, lang, longdesc, maxlength, media, method, multiple, name, nohref, noshade, nowrap, prompt, readonly, rel, rev, rows, rowspan, rules, scope, selected, shape, size, span, start, summary, tabindex, target, title, type, usemap, valign, value, vspace, width, itemprop

Note that the id attribute is not whitelisted.

See Contributing