[web] Warn user about pending requests when attempting to close the browser(-tab)

[kulmann]

Description

When a user attempts to close the browser(-tab) we should warn them about pending requests (e.g. from batch operations) that would be aborted by closing.

User Stories

• As a user who started a batch operation for deleting a large number of files, I'd be annoyed if closing the browser aborted my batch operation, because I expect the process to finish.

Value

Educate users about batch operations being orchestrated by the web ui. -> less bug reports.

Acceptance Criteria

• if the loadingService has any unfinished process and the user attempts to close the browser(-tab), show a warning that closing the browser(-tab) would abort pending requests.
• Closing the browser while an upload is running already has such a message. There should not be two after this story is done (i.e. a: have a new concept and also use it for uploads or b: make an exception for uploads so that we continue to use the already existing mechanism there, slightly preferring a, but might not be feasible. needs to be checked.)
• Closing the browser while a document editing session is in a dirty state (i.e. file not saved) also already has such a message. see above.

Definition of ready

• Everybody needs to understand the value written in the user story
• Acceptance criteria have to be defined
• All dependencies of the user story need to be identified
• Feature should be seen from an end user perspective
• Story has to be estimated
• Story points need to be less than 20

Definition of done

• Functional requirements
  • Functionality described in the user story works
  • Acceptance criteria are fulfilled
• Quality
  • Code review happened
  • CI is green (that includes new and existing automated tests)
  • Critical code received unit tests by the developer
• Non-functional requirements
  • No sonar cloud issues

Additional context

This was pointed out by @mbuonaccorsi in #9182 (comment) - thanks for the input.

[AlexAndBear]

Maybe some kind of axios http interceptor possible

[JammingBen]

I guess this is what we're looking for: https://developer.mozilla.org/en-US/docs/Web/API/Window/beforeunload_event. Then just check for loadingService.isLoading() and show the user some prompt.

[kulmann]

I guess this is what we're looking for: https://developer.mozilla.org/en-US/docs/Web/API/Window/beforeunload_event. Then just check for loadingService.isLoading() and show the user some prompt.

We're already using exactly that in the AppWrapper and for active upload queues :-)