Forum:What makes the Recent Changes page have an auto-refresh option?

I've looked through the system message pages (the MediaWiki namespace — fortunately I know how to get to the index page, and thus view only the customised messages), and if whatever adds this functionality is in there, I can't see it. Is it in one of the .js files?

I would like to know the answer so I can add this functionality to wikis I admin. — RobertATfm (talk) 08:19, July 30, 2013 (UTC)