The Server instance
The Server instance (often called io
in the code examples) has a few attributes that may be of use in your application.
It also inherits all the methods of the main namespace, like namespace.use()
(see here) or namespace.allSockets()
.
Server#engine
A reference to the underlying Engine.IO server.
It can be used to fetch the number of currently connected clients:
const count = io.engine.clientsCount;
// may or may not be similar to the count of Socket instances in the main namespace, depending on your usage
const count2 = io.of("/").sockets.size;
Or to generate a custom session ID (the sid
query parameter):
const uuid = require("uuid");
io.engine.generateId = (req) => {
return uuid.v4(); // must be unique across all Socket.IO servers
}
Events
The Server instance emits one single event (well, technically two, but connect
is an alias for connection
):
connection
This event is fired upon a new connection. The first argument is a Socket instance.
io.on("connection", (socket) => {
// ...
});
Complete API
The complete API exposed by the Server instance can be found here.