What's a simple way in Google Chrome to insert Javascript into sites?

Question

I would like to be able to add custom snippets of javascript to any site that matches a regex. This is mostly because of sites that I use daily because of specialized content, b

Answer 1

The answer was Tampermonkey.

https://chrome.google.com/webstore/detail/dhdgffkkebhmkfjojejmpbldmpobfkfo