How to understand who left the site in the socket io library?

Question

Node.js

Hello, I have a question. I have a site with the socket io library connected, and I need to somehow find out who left the site, how to implement this?

Answer 1

Assign an ID to each, and handle the disconnect event :)

socket.on('disconnect', function() {
  ....
});

Answer 2

When connecting, assign an id, something like

io.sockets.on('connection', function (socket) {
     clientid = socket.id;

And when disconnecting, see what id