Fully document which HTML tags are allowed in GitHub flavored Markdown

[nvkelso]

In the related issue #119 (comment) @bkeepers mentioned "unsafe" HTML tags and attributes aren't allowed. Please clearly document which tags and attributes are safe and supported.

[bkeepers]

Here is the exact code we run: https://github.com/jch/html-pipeline/blob/master/lib/html/pipeline/sanitization_filter.rb

Feel free to submit pull requests to make changes.

[nvkelso]

Sorry, unless that link is provided in the main Readme file, this doesn't count.

[forivall]

I love how https://help.github.com/articles/github-flavored-markdown/ says to refer to github/markup for the list of tags, but it's not mentioned anywhere. And by love, I mean that it's pretty damn annoying.

[pchaigno]

@forivall You should report it to support@github.com ;)

[bishopb]

Highlighting the relative lines from @bkeepers link:

https://github.com/jch/html-pipeline/blob/master/lib/html/pipeline/sanitization_filter.rb#L44-L106

Code is speech, after all.

[gregglind]

Is there some reason that span isn't allowed?

PROTECT ME FROM THE INTERNETS, PLZ.

[nektro]

h1 h2 h3 h4 h5 h6 h7 h8 br b i strong em a pre code img tt div ins del sup sub p ol ul table thead tbody tfoot blockquote dl dt dd kbd q samp var hr ruby rt rp li tr td th s strike summary details

[nektro]

why isn't <style> allowed?

[kivikakk]

@nektro it would allow you to change the styling of the entire page, compromising the usability of the website. GitHub isn't a web host.

[nektro]

@kivikakk this is slightly off-topic, but in response, this is why whatwg/html#1226 should not have gone though