Didn't work for me with both Monobook and Vector. Paradoctor (talk)
It might be an idea to have the script at User:Paradoctor/CatVisor.js then if someone want to include it they can simple add
importScript('User:Paradoctor/CatVisor.js');
Having a .js file extension will also mean you get a better code editor. Also have a look at jQuery it will make your code a lot cleaner.--Salix alba (talk): 06:25, 15 August 2014 (UTC)