How to tell which action and filter hooks are available in a particular version of WordPress
If you ever need to know if a particular hook is available in the latest version of WordPress, Adam Brown has got you covered. If you ever need to know if a hook is available in a version of WordPress from – gasp – years ago….. Adam Brown has got you covered. Brown maintains a database of the hooks that have been added, removed, renamed or remain unchanged in each WordPress release going all the way back to 1.2.1. His code also scrapes the documentation for the hooks and filters so you can contribute by adding to the documentation over at the official WordPress codex.