Loofah provides some built-in scrubbers for sanitizing with HTML5lib's whitelist and for accomplishing some common transformation tasks.
:strip removes unknown/unsafe tags, but leaves behind the pristine contents:
unsafe_html = "ohai! <div>div is safe</div> <foo>but foo is <b>not</b></foo>" Loofah.fragment(unsafe_html).scrub!(:strip) => "ohai! <div>div is safe</div> but foo is <b>not</b>"
:prune removes unknown/unsafe tags and their contents (including their subtrees):
unsafe_html = "ohai! <div>div is safe</div> <foo>but foo is <b>not</b></foo>" Loofah.fragment(unsafe_html).scrub!(:prune) => "ohai! <div>div is safe</div> "
:escape performs HTML entity escaping on the unknown/unsafe tags:
unsafe_html = "ohai! <div>div is safe</div> <foo>but foo is <b>not</b></foo>" Loofah.fragment(unsafe_html).scrub!(:escape) => "ohai! <div>div is safe</div> <foo>but foo is <b>not</b></foo>"
:whitewash removes all comments, styling and attributes in addition to doing markup-fixer-uppery and pruning unsafe tags. I like to call this "whitewashing", since it's like putting a new layer of paint on top of the HTML input to make it look nice.
messy_markup = "ohai! <div id='foo' class='bar' style='margin: 10px'>div with attributes</div>" Loofah.fragment(messy_markup).scrub!(:whitewash) => "ohai! <div>div with attributes</div>"
One use case for this scrubber is to clean up HTML that was cut-and-pasted from Microsoft Word into a WYSIWYG editor or a rich text editor. Microsoft’s software is famous for injecting all kinds of cruft into its HTML output. Who needs that crap? Certainly not me.
:nofollow adds a rel="nofollow" attribute to all links
link_farmers_markup = "ohai! <a href='http://www.myswarmysite.com/'>I like your blog post</a>" Loofah.fragment(link_farmers_markup).scrub!(:nofollow) => "ohai! <a href='http://www.myswarmysite.com/' rel="nofollow">I like your blog post</a>"
:unprintable removes unprintable Unicode characters.
markup = "<p>Some text with an unprintable character at the end\u2028</p>" Loofah.fragment(markup).scrub!(:unprintable) => "<p>Some text with an unprintable character at the end</p>"
You may not be able to see the unprintable character in the above example, but there is a U+2028 character right before the closing </p> tag. These characters can cause issues if the content is ever parsed by JavaScript - more information here:
http://timelessrepo.com/json-isnt-a-javascript-subset
A hash that maps a symbol (like :prune) to the appropriate Scrubber (Loofah::Scrubbers::Prune).
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