javascript - Socket IO Rooms: Get list of clients in specific room

Question

I'm trying to display a list of clients in a specific room. I just want to show their username, and not their socket id.

This where I'm at:

socket.set('nickname', "Earl");  
socket.join('chatroom1');
console.log('User joined chat room 1);

var roster = io.sockets.clients('chatroom1');
for ( i in roster )
{
   console.log('Username: ' + roster[i]);   
}

Haven't had any luck getting it to list Socket IDs or anything. Would like it to return the nicknames however.

Answer 1

In socket.IO 3.x

New to version 3.x is that connected is renamed to sockets and is now an ES6 Map on namespaces. On rooms sockets is an ES6 Set of client ids.

//this is an ES6 Set of all client ids in the room
const clients = io.sockets.adapter.rooms.get('Room Name');

//to get the number of clients in this room
const numClients = clients ? clients.size : 0;

//to just emit the same event to all members of a room
io.to('Room Name').emit('new event', 'Updates');

for (const clientId of clients ) {

     //this is the socket of each client in the room.
     const clientSocket = io.sockets.sockets.get(clientId);

     //you can do whatever you need with this
     clientSocket.leave('Other Room')

}

In socket.IO 1.x through 2.x

Please refer the following answer: Get list of all clients in specific room. Replicated below with some modifications:

const clients = io.sockets.adapter.rooms['Room Name'].sockets;   

//to get the number of clients in this room
const numClients = clients ? Object.keys(clients).length : 0;

//to just emit the same event to all members of a room
io.to('Room Name').emit('new event', 'Updates');

for (const clientId in clients ) {

     //this is the socket of each client in the room.
     const clientSocket = io.sockets.connected[clientId];

     //you can do whatever you need with this
     clientSocket.leave('Other Room')
}