I have a script which makes certain DHTML modifications, but don’t know how to make it called after refreshing—such as pushing [↻ newest changes]—in new Special:Watchlist or RecentChanges.
“$( document ).ready( function () … )” doesn’t help. Also, I found no hooks related to Watchlist in https://doc.wikimedia.org/mediawiki-core/master/js/#!/api/mw.hook
I think you can attach your callback to the onclick event of the button in question (now I can't say more, I'm from mobile... apologies).
Pushing [↻ newest changes] isn’t the only way how such pages are updated without reloading. Of course, thought about redefining events manually, but it is crude and error-prone.
I'd also be interested in this. Mainly because I want to get this code which auto-expands grouped-entries, to be triggerable from a new button (which would be useful after clicking the [↻ newest changes] button). (See also phab:T176555 where I filed the above as a suggested feature)