ANSI OSC 52 is a sequence to transport some data from remote console app to client's clipboard. For example, tmux can use it on remote side, and xterm (terminal app), Windows terminal and a number of others -- on client side. It would be very convenient to have such a feature in xterm.js.
Here is a simple test which sends a string from remote to local clipboard (taken here):
printf "\033]52;c;$(printf "%s" "blabla" | base64)\a"