Topic on Talk:OOUI/Widgets/Popups

Hello, I made a browser extension for the internet archive that adds a link to cited books that includes a little detail popup. I am working to port this over as a gadget, but I am getting "Uncaught TypeError: Cannot read property 'PopupWidget' of undefined" when I call "OO.ui.PopupWidget({...})."

You need to declare your dependency on the relevant bits of OOUI and get MediaWiki to load it via mw.loader.using( [ 'oojs-ui-core' ], function () { … } ).