Prevent page refresh/reload by throwing an alert message

[BaccanoMob]

First Check

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• I have checked the FAQs for a similar question and didn't find it.
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Example Code

class LoadingSpinnerModal(ui.dialog):
    def __init__(self) -> None:
        super().__init__(value=False)
        self.props("persistent backdrop-filter='blur(5px)'")
        with self:
            ui.spinner()

    async def loading_while(self, async_function=None, **kwargs):
        self.open()
        if async_function is not None:
            await async_function(**kwargs)
        self.close()

@ui.page("/")
def some_page():
    ui.add_body_html("""
<script>
window.addEventListener('beforeunload', function (e) {
  e.preventDefault();
});
</script>
""")
    loadingDialog = LoadingSpinnerModal()

    ui.button(
        "Press", on_click=lambda e: loadingDialog.loading_while(asyncio.sleep, delay=15)
    )

Description

I found that

<script>
window.addEventListener('beforeunload', function (e) {
  e.preventDefault();
});
</script>

Shows below alert when trying to refresh/reload the page

Note that script in example code works only if you respond to the alert within like 2-3 seconds. If its longer the connection is lost if I leave the alert for too long and the spinner is also frozen when the alert is active (after cancelling it may loop forever sometimes).

Is there a way to allow the ui to function while the pop up shown? or any other way to prevent refresh?

NiceGUI Version

2.19.0

Python Version

3.12.10

Browser

Chrome

Operating System

Linux

Additional Context

Other possible solutions I thought of were (though it is in case I have to allow refresh to take place)

1. If its form filling, then bind data to user storage
2. If its some async process, then follow global worker example but the example does not allow multiple users.

[thetableman]

Perhaps related to #2286

[BaccanoMob]

Yes, you are right. I guess I need to upvote #2410 to get feature.