Hi, basically, HTML comments are currently handled like elements in html.diff's flatten_el, which leads to interesting results:

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from lxml.html.diff import htmldiff

a = '<p>test</p>' b = '<p>test<!-- Hey --></p>'

print(htmldiff(a,b)) <p>test <ins><<cyfunction comment at>>Hey <cyfunction comment at>></cyfunction></cyfunction></ins> </p>

I added a check to not include comments in the generated token list, which effectively strips all comments from the diff: diff --git a/src/lxml/html/diff.py b/src/lxml/html/diff.py index 5d143bd2..9d4a4f72 100644 --- a/src/lxml/html/diff.py +++ b/src/lxml/html/diff.py @@ -4,7 +4,7 @@ from __future__ import absolute_import import difflib from lxml import etree -from lxml.html import fragment_fromstring +from lxml.html import fragment_fromstring, HtmlComment import re __all__ = ['html_annotate', 'htmldiff'] @@ -688,6 +688,14 @@ def flatten_el(el, include_hrefs, skip_tag=False): If skip_tag is true, then the outermost container tag is not returned (just its contents).""" + + if isinstance(el, HtmlComment): + if el.tail: + end_words = split_words(el.tail) + for word in end_words: + yield html_escape(word) + return + if not skip_tag: if el.tag == 'img': yield ('img', el.get('src'), start_tag(el)) jens