This task is about MediaWiki's [Popups extension](https://www.mediawiki.org/wiki/Extension:Popups) (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.
= Developer notes
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.
== Testing criteria
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