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

Witchcraft is another Google Chrome extension for loading custom Javascript and CSS, and it is supposedly for more avanced users. The older dotjs project repository lists Witchcraft as its successor.