Note: After saving, you have to bypass your browser's cache to see the changes. Google Chrome, Firefox, Microsoft Edge and Safari: Hold down the ⇧ Shift key and click the Reload toolbar button. For details and instructions about other browsers, see Wikipedia:Bypass your cache.
mw.loader.load('//en.wikipedia.org/w/index.php?title=User%3ATheopolisme%2FScripts%2FajaxWatchlist.js&action=raw&ctype=text/javascript'); // [[User:Theopolisme/Scripts/ajaxWatchlist.js]]