Original sentence "The most convenient way to do this is:" is not ended before starting next paragraph at the beginning.
See https://www.mediawiki.org/w/index.php?title=OOUI/Using_OOUI_in_MediaWiki&diff=prev&oldid=5999649
Assuming "The most convenient way to do this is using the following." --Christian 🇫🇷 FR (talk) 12:46, 23 June 2023 (UTC)
I think it was a very big mistake to mark this page up for translation. It's now impossible to edit it properly, and so this page will be (even more) abandoned. Please consider reverting your changes, and ask first in future.
It was in translation before I came, so i trust people are responsible enough in what they do here. Now I can hardly accept to revert my changes since it represents days/weeks of work for the community and it cannot be blown out in three sentences. Wish a solution be adopted through consensus if my proposal is not satisfying -- Christian 🇫🇷 FR (talk) 19:05, 23 June 2023 (UTC)
trying to ping the author @Matma Rex
https://www.mediawiki.org/w/index.php?title=OOUI/Using_OOUI_in_MediaWiki&diff=next&oldid=2237275
@Wladek92 Yes, I think that's what I meant. Thanks for clarifying it.
@Jdforrester (WMF) I don't mind the translation. It's true that the markup is annoying, but sometimes we must suffer for greatness. The page hasn't really seen changes since 2019, because nothing has changed about how OOUI is used, so I don't think anyone will be annoyed in practice.
I see an anomaly using examples of scripts from OOUI/Widgets/Buttons_and_Switches and others on this site – not all Wikimedia wikis appear to export the “OO.ui” thing to me. On some pages var btn = new OO.ui.ButtonWidget( { ⋯ } ); (in Scratchpad) runs fine, whereas others (including those from www.mediawiki.org) produce /* Exception: TypeError: OO.ui is undefined @Scratchpad/1:10:5 */
What is the difference?
You need to load OOUI. On some pages the page happens to already be using OOUI, but you shouldn't rely on this, and should run:
$this->getOutput()->enableOOUI();
Clear as for “the page happens to already be using OOUI”, but for “should run”… hey, am I looking like a person who can run anything on a production Wikimedia server? Let alone inside any of MediaWiki installations there. Scratchpad is a client-side tool for JavaScript, not a thing that generates HTML pages.
Oh, if you're writing a user script or gadget, you should read the gadget-specific instructions.
You'll want to wrap your code in:
mw.loader.using( 'oojs-ui-core' ).done( function () {
// …
}