socket.broadcast.emit() 和 io.to(socketID).emit() 之间有什么区别？

Question

Getting started with using socket.io library. There is this use case where I need to broadcast to all connected clients except the sender. Therefore, I had used the socket.broadcast.emit() .

I came across another technique to achieve the same which was io.to(socketID).emit() . From what I understand, this method emits to a room with an id = socketID (ideally this room would have just one client by default and the event will be emitted to this client).

Is there any other functional difference between these two methods or can I use them interchangeably?

Tried both ways, and they both seemed to work fine. Just wanted to know if there's any difference and any limitations to either way of emitting.

io.on("connection", (socket) => {
    setInterval(() => {
        socket.broadcast.emit('dummy_event', 'new_testing_21jan');
    }, 5000);
}

and

io.on("connection", (socket) => {
    setInterval(() => {
        io.to(socket.id).emit('dummy_event', 'new_testing_21jan');
    }, 5000);
}

Answer 1

socket.broadcast.emit() broadcasts an event to all connected clients except the sender.

io.to(socketID).emit() is used to send event to specific socket by socket ID.

Both can be used interchangeably in your use case, but io.to(socketID).emit() is more specific and useful for emitting events to specific clients.

socket.broadcast.emit() wants to send the event to all clients except the sender.

You can use io.in(roomName).emit() to send an event to all customers in a particular room.