testing a website after making changes to many pages on the site

I have a lot of .php and/or .php files on my site. Is there a way to go through each site/page and work out which ones(if any) have errors in the console in the broswer?

More generally, I am looking at making a change to many pages on my site and I am just wondering what is the best way to automate the test process to see that I did not break anything with the changes I made.

Note: the errors in the console in the broswer, will give me errors, but it would not show errors that only the human eye could detect.