There are some issues with the new feature from MDL-76242 that we can improve before it's released (as this is still brand new, we might as well improve it now rather than wait for random errors/bugs in the future)

Javascript

1. The whole AJAX request should be replaced with repository method to achieve the same;
2. Undefined this.userId property;
3. Incorrect (jQuery style) promise handling, it should use native then/catch
   • Catch is missing
4. Copy/pasted docs (also line 27)

Index page

1. Unreachable code here [*];
2. There are no tests

[*] To see the problem with this code, try visiting WWWROOT/contentbank/index.php?displayunlisted=0 and using the toggle to "Show unlisted content" - it will turn the preference on, but then reload the page and turn the preference off again (but the checkbox shows the wrong value)