addToolbarButtons.js simplifies adding buttons to the edit toolbar above the text area when editing the source of wiki pages.
The "Enhanced editing toolbar" (part of the WikiEditor MediaWiki extension) is now the default toolbar when editing the source code of articles, but some users are still using the original toolbar.
addToolbarButtons.js adds your buttons to whichever of the two toolbars appears above the text area when editing an article. (You can turn on and off the Enhanced editing toolbar from your preferences >> Editing tab >> Editor section >> "Enable enhanced editing toolbar" checkbox.) This script can not add buttons to the VisualEditor's toolbar.
Please comment on the talk page if you find this script useful and if you have any questions or suggestions. Also, please see my other useful scripts.
The source code of the script is here: User:V111P/js/addToolbarButtons.js
You can edit this page. If I don't like or understand something you wrote, I will correct it. ;)