Thanks for your reply. Do you know other option?
More background about the reason of checking HTML revision:
We are currently getting every wikipedia revision by monitoring "api.php?action=query&prop=recentchange", and get both wikitext and HTML of the revision. From the comment of code, it seems we want to reduce the number of requests to api.php, so we are fetching HTML without using api.php.
The issue with fetching HTML without using api.php is that it's possible to get HTML at a different revision from the wikitext. So we need to find out a way to detect if the revision.