Tweak IE Conditional Comment with Nokogiri without converting entities

Question

I have an XHTML file with an HTML5 Shiv in the head:

<!--[if lt IE 9]>
  <script src='../common/html5.js' type='text/javascript'></script>
<![endif]-->

Using Nokogiri I need to adjust the path in that comment, stripping off the ../. However, any changes to the .content of the comment node results in XML output that converts the > and < to entities:

XML = <<ENDXML
<r><!--[if lt IE 9]>
  <script src='../common/html5.js' type='text/javascript'></script>
<![endif]--></r>
ENDXML

require 'nokogiri'
doc = Nokogiri.XML(XML)
comment = doc.at_xpath('//comment()')
comment.content = comment.content.sub('../','')
puts comment.to_xml
#=> <!--[if lt IE 9]&gt;
#=>   &lt;script src='common/html5.js' type='text/javascript'&gt;&lt;/script&gt;
#=> &lt;![endif]-->

The original source is valid XML/XHTML. How can I get Nokogiri not to convert the entities inside this comment during tweaking?

Answer 1

The Nokogiri docs for content= say:

The string gets XML escaped, not interpreted as markup.

So rather than using that, you could replace the node with a new one, using replace and an explicitly created comment node:

XML = <<ENDXML
<r><!--[if lt IE 9]>
  <script src='../common/html5.js' type='text/javascript'></script>
<![endif]--></r>
ENDXML

require 'nokogiri'
doc = Nokogiri.XML(XML)
comment = doc.at_xpath('//comment()')

# this line is the new one, replacing comment.content= ...
comment.replace Nokogiri::XML::Comment.new(doc, comment.content.sub('../',''))

# note `comment` is the old comment, so to see the changes
# look at the whole document
puts doc.to_xml

Output is:

<?xml version="1.0"?>
<r>
  <!--[if lt IE 9]>
  <script src='common/html5.js' type='text/javascript'></script>
<![endif]-->
</r>