MediaWiki:Common.js

Note: After publishing, you may have to bypass your browser's cache to see the changes.

Firefox / Safari: Hold Shift while clicking Reload, or press either Ctrl-F5 or Ctrl-R (⌘-R on a Mac)
Google Chrome: Press Ctrl-Shift-R (⌘-Shift-R on a Mac)
Edge: Hold Ctrl while clicking Refresh, or press Ctrl-F5.

mw.loader.using('mediawiki.util').then(function() {
    document.body.classList.add('is-menu-expanded');
});