copy event fires when the user initiates a copy action through the browser's user interface.
The event's default action is to copy the selection (if any) to the clipboard.
A handler for this event can modify the clipboard contents by calling
setData(format, data) on the event's
ClipboardEvent.clipboardData property, and cancelling the event's default action using
However, the handler cannot read the clipboard data.
It's possible to construct and dispatch a synthetic
copy event, but this will not affect the system clipboard.