"Copy to clipboard" does not work reliably in the browser viewer

georgehuang · 05-01-2021, 12:39 AM

In the browser viewer, I have tried copying selection with a keyboard shortcut and with selection popup. Both can fail with a successful rate lower than 50%. It usually requires multiple clicks to copy text to the clipboard.

In Firefox's console, I got:

Code:

document.execCommand(‘cut’/‘copy’) was denied because it was not called from inside a short running user-generated event handler.

With a bit of searching, it appears that "Document.execCommand()" is now deprecated and should be avoided using.

A direct alternative to this command is not provided, but the new Clipboard API seems to be the way to go.

kovidgoyal · 05-01-2021, 01:14 AM

the new clipboard api only works over https and the viewer already uses it when execcommand fails with an exception, if it is available.

georgehuang · 05-01-2021, 01:44 AM

Huh, I am using https, but copying still fails quite often. Should have tried more browsers. Now it seems this only happens in Firefox. Will try to figure out what goes wrong.

kovidgoyal · 05-01-2021, 02:09 AM

probably when it fails firefox is failing to raise an exception.

georgehuang · 05-02-2021, 12:06 PM

Tried to look into the dev tool a bit more. So when an exception is raised (console shows the warning), copying will be successful. However, if console shows no warning, that is when copying becomes flaky. Sometimes it still works without a warning, sometimes it just does not. Interestingly, if I turn on Debugger, for those failed copying actions I get an error: "No permission to write to clipboard". Without Debugger, no error is shown. Again, this only happens in Firefox.

kovidgoyal · 05-02-2021, 12:46 PM

Sounds like a bug in firefox. Either the command should succedd or it should fail and firefox should raise an exception. If it is failing and not raising an exception that is a bug in firefox.

georgehuang · 05-02-2021, 10:48 PM

Yeah, I think it is. Just have to wait for Firefox to fix this bug.

05-01-2021, 12:39 AM	#1
georgehuang Enthusiast Posts: 37 Karma: 10 Join Date: Oct 2020 Device: MacBook, iPhone, Kindle Paperwhite	"Copy to clipboard" does not work reliably in the browser viewer In the browser viewer, I have tried copying selection with a keyboard shortcut and with selection popup. Both can fail with a successful rate lower than 50%. It usually requires multiple clicks to copy text to the clipboard. In Firefox's console, I got: Code: document.execCommand(‘cut’/‘copy’) was denied because it was not called from inside a short running user-generated event handler. With a bit of searching, it appears that "Document.execCommand()" is now deprecated and should be avoided using. A direct alternative to this command is not provided, but the new Clipboard API seems to be the way to go.

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05-01-2021, 01:14 AM	#2
kovidgoyal creator of calibre Posts: 43,842 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	the new clipboard api only works over https and the viewer already uses it when execcommand fails with an exception, if it is available.

05-01-2021, 01:44 AM	#3
georgehuang Enthusiast Posts: 37 Karma: 10 Join Date: Oct 2020 Device: MacBook, iPhone, Kindle Paperwhite	Huh, I am using https, but copying still fails quite often. Should have tried more browsers. Now it seems this only happens in Firefox. Will try to figure out what goes wrong.

05-01-2021, 02:09 AM	#4
kovidgoyal creator of calibre Posts: 43,842 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	probably when it fails firefox is failing to raise an exception.

05-02-2021, 12:06 PM	#5
georgehuang Enthusiast Posts: 37 Karma: 10 Join Date: Oct 2020 Device: MacBook, iPhone, Kindle Paperwhite	Tried to look into the dev tool a bit more. So when an exception is raised (console shows the warning), copying will be successful. However, if console shows no warning, that is when copying becomes flaky. Sometimes it still works without a warning, sometimes it just does not. Interestingly, if I turn on Debugger, for those failed copying actions I get an error: "No permission to write to clipboard". Without Debugger, no error is shown. Again, this only happens in Firefox.

05-02-2021, 12:46 PM	#6
kovidgoyal creator of calibre Posts: 43,842 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Sounds like a bug in firefox. Either the command should succedd or it should fail and firefox should raise an exception. If it is failing and not raising an exception that is a bug in firefox.

05-02-2021, 10:48 PM	#7
georgehuang Enthusiast Posts: 37 Karma: 10 Join Date: Oct 2020 Device: MacBook, iPhone, Kindle Paperwhite	Yeah, I think it is. Just have to wait for Firefox to fix this bug.