Determining A Significant Change In A Web Page

The problem with many web pages today is that they include useless hidden pieces of constantly changing information that serves no purpose to the general web or anything else besides debugging. A pretty good example of this is one that I found on my own blog, and removed, as I was experimenting with the code in this post: view source print? 1 <!-- 12 queries. 0.274 seconds. --> This really serves no purpose to anybody but the the few debuggers who might be looking at the code for performance reasons once every so often. You may be saying what’s the big deal, it is a comment and it is not seen by the user, so who cares? Well you are right nobody does care, and this post isn’t going to change that fact, this type of debugging flair is going to continue on for the entire lifespan of the web. But it does cause problems for any service that wants to figure out if your webpage has been changed overtime. Like search engines, proxy caches, and the service I am working on that inspired this post.