#save $var->content as html file (to match with next day's file) in the normal manner (not shown here)

$var=$user_agent->get('url') ;
$parsed_html=parse_html($var->content);
$txt_on_the_page=$parsed_html->format;

#for the earlier saved html 
$old_parsed_html=parse_html($oldfile->content);
$txt_on_the_old_page=$old_parsed_html->format;


# now compare $txt_on_the_page & $txt_on_the_old_page. I have put very less code with very optimistic approach. But with little effort you will get what you need.