Hi,
I am excited to announce that on Tuesday, August 26, we will be deploying the GlobalCssJs extension,[1] which enables per-user JavaScript and CSS across public Wikimedia wikis. Users will be able to create global.js[2] and global.css[3] subpages on Meta-Wiki and these pages will automatically be loaded across all public Wikimedia wikis. There is documentation available[4] if you want to load JavaScript on a subset of all wikis (e.g., all Wikisources, all French language projects, etc.).
Some users currently have manually set up global JavaScript/CSS by creating local user subpages (e.g., monobook.js/css subpages) to load their global scripts. For these users, the deployment of the extension will mean that modules will be loaded twice, and they will no longer be included in global scope[5]. A script has been prepared to delete these page if they were created in the standard format. Users can signup at a Meta-Wiki page[6] to have this done on their behalf once the extension is deployed.
Thanks, -- Legoktm
[1] https://www.mediawiki.org/wiki/Extension:GlobalCssJs [2] https://meta.wikimedia.org/wiki/Special:MyPage/global.js [3] https://meta.wikimedia.org/wiki/Special:MyPage/global.css [4] https://www.mediawiki.org/wiki/Help:Extension:GlobalCssJs [5] https://www.mediawiki.org/wiki/Help:Extension:GlobalCssJs#Variables [6] https://meta.wikimedia.org/wiki/GlobalCssJs