gistfile1.rb

# Allow for the HTML elements / attributes to be custom specified
# Used like so:
# scrubber = WhitelistScrubber.new(:whitelist_elements => %w(span div) , :whitelist_attributes => %w(style class) )
# cleaned = Loofah.fragment(input).scrub!(scrubber).to_s
# This scrubber does not have graceful degradation when the elements/attributes are NOT set.
class WhitelistScrubber < Loofah::Scrubber
  attr_accessor :whitelist_elements, :whitelist_attributes
  
  def initialize(options = {}, &block)
    if options[:whitelist_elements]
      @whitelist_elements = options[:whitelist_elements]
    end
    if options[:whitelist_attributes]
      @whitelist_attributes = options[:whitelist_attributes]
    end
    super(options, &block)
  end
  def scrub(node)
    case node.type
    when Nokogiri::XML::Node::ELEMENT_NODE
      node.remove unless @whitelist_elements.include?(node.name)
      node.attributes.each do |attr|
        unless @whitelist_attributes.include?(attr.first)
          node.remove_attribute(attr.first)
        end
      end
    when Nokogiri::XML::Node::TEXT_NODE, Nokogiri::XML::Node::CDATA_SECTION_NODE
      return Loofah::Scrubber::CONTINUE
    end
    Loofah::Scrubber::STOP     
  end
end

Thanks for sharing this. Given that it's 4 years old, have you made any observations/seen any issues since? Or does it work as it it should?