This task is about MediaWiki's Popups extension (which is sometimes also called "Page-Previews" or "Hovercards").
The line preview.el.hover( behavior.previewDwell, behavior.previewAbandon ); in the file src/ui/renderer.js causes a warning in the console of your web browser's developer tools:
JQMIGRATE: jQuery.fn.hover() is deprecated
See https://github.com/jquery/jquery-migrate/blob/3.0.1/warnings.md for documentation how to replace it.
For anyone who plans to work on this, https://gerrit.wikimedia.org/r/#/c/381780/ and https://gerrit.wikimedia.org/r/#/c/382196/ are similar merged patches.
The Popups extension uses a build process.
After making your change you'll need to run the following code
npm install npm run build
and commit the dist folder as part of your patch.
Test that page previews:
- appear and disappear normally
- settings open and close
- note any strange behavior
note: for this, it's not necessary to go through the entirety of the test cases