The host may run this to respond with **OK** to confirm, prompt, and
beforeunload dialogs. Do not run this method to indicate cancel.
From JavaScript, this means that the confirm and beforeunload function
returns TRUE if Accept is run. And for the prompt function it returns
the value of ResultText if Accept is run and otherwise returns
FALSE.
The D Programming Language's Unofficial Docs
beta
The host may run this to respond with **OK** to confirm, prompt, and beforeunload dialogs. Do not run this method to indicate cancel. From JavaScript, this means that the confirm and beforeunload function returns TRUE if Accept is run. And for the prompt function it returns the value of ResultText if Accept is run and otherwise returns FALSE.