Added upload pending prompt on close/reload

[anastr0]

Description

Added an unload event listener that prompts user if there are pending uploads while user closes/ reloads/ navigates to another URL.

Related Issue

• Fixes Warn leaving users about running uploads #2590

Motivation and Context

The pending uploads are cancelled on closing/reloading window. A prompt is required to warn users of upload cancellation.

How Has This Been Tested?

• tested with the latest changes from owncloud/web master branch
• tested by uploading many files and also with large files
• tested on tab close/ reload/ navigating to another URL
• tested on Chrome 88.0 and Firefox 86.0

Screenshots (if appropriate):

Types of changes

• Detect tab close/ reload/ navigation and prompt if any uploads are pending.

Checklist:

• Added unload event listener
• Remove unload event listener before component destroy

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[CLAassistant]

All committers have signed the CLA.

[pascalwengerter]

Works like a charm locally, I'll do a quick research and see if we can add a test to our suite :)

@anaswaratrajan could you add a changelog item to this PR inside the changelog/unreleased folder? Name of the file should follow the schema of enhancement-your-change (since it's neither a bugfix nor a breaking change), and for the content of the file you can take inspiration from the existing changelog items!

[pascalwengerter]

LGTM 🚀

[pascalwengerter]

@kulmann there seems to be a way to test this behaviour (see SeleniumHQ/selenium#8638), but not sure if we want to have tests for this and if so on which level to add them..

[anastr0]

@pascalwengerter @kulmann Should I look into adding a unit test using jest?

[pascalwengerter]

@pascalwengerter @kulmann Should I look into adding a unit test using jest?

That would be lovely, yeah! Not sure how to handle long-running uploads in there, but perhaps setting the uploadPending somewhere between 0 and 100 manually would be a first step?

[kulmann]

Thanks for your contribution! 🚀