Handling exceptions for writeText()

Riproducete il problema con gli esempi HTML forniti, confrontando il comando writeText() con la chiamata a navigator.clipboard.writeText(). Tracciate il modo in cui la promise degli appunti rifiutata viene gestita da catch e on exception, quindi verificate che l'errore raggiunga il gestore senza segnalare il successo né registrare un rifiuto non gestito.

I'm unable to handle exception while a coping text to a clipboard idiomatically. Maybe it's not the only place for such behavior but it's the only one I've found.

I'm using qutebrowser and I've blocked programmatic access to a clipboard for websites.
Unfortunately, I don't know how to block access the same way for other browses =\

Use case: I want to show a notification that user has successfully copied text to the clipboard or if there is an error. To do so I have to handle exception that writeText() might throw.

I expect the following code to work:

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       writeText('text to copy') into the navigator's clipboard
       then put 'Success' into the next <output/>
     catch e
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

Output shows Success and console logs Uncaught (in promise) DOMException: Write permission denied.. catch doesn't seem to work.

There is another way to catch exceptions for an element (on exception):

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       writeText('text to copy') into the navigator's clipboard
       then put 'Success' into the next <output/>
     on exception(e)
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

The same result: output shows Success and console logs Uncaught (in promise) DOMException: Write permission denied..

Feels like exception isn't related to the element in any way.

Sanity check

Just to make sure that exceptions are catchable:

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       throw 'I am thrown manually'
       then put 'Success' into the next <output/>
     catch e
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

Shows Error: I am thrown manually in output and console is clean.

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       throw 'I am thrown manually'
       then put 'Success' into the next <output/>
     on exception(e)
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

This one is interesting. It shows Error: in output and picrelated in console

Workaround

I've managed to get it working by calling writeText() in a more traditional way:

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       call navigator.clipboard.writeText('text to copy')
       then put 'Success' into the next <output/>
     catch e
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

Output has Error: NotAllowedError: Write permission denied. and a clean console.

<script src="https://unpkg.com/hyperscript.org@0.9.12"></script>

<button
  _="on click
       call navigator.clipboard.writeText('text to copy')
       then put 'Success' into the next <output/>
     on exception(e)
       put `Error: $e` into the next <output/>">
    Copy
</button>
<output>--</output>

This one behaves the same way it does in sanity check. In catches the exception but error is empty while console has the following: