Socket.io join another client to a room

Question

My goal is when A user click on B user, they'll join in a room. I'm holding socket.id in array for all clients.

//CLIENT SIDE FOR A//
$('.chat-start').on('click', function(event) {
        event.preventDefault();
        var room_id = '72xaz132s'
        var target_id = $('.target').data('id');
        socket.emit('force join room', room_id, target_id);
    });

//SERVER SIDE FOR A AS AN EXAMPLE//

var clients {'customIDA' : socket.id for a, 'customIDB' : socket.id for b}

socket.on('force join room', function (roomid, customIDB) { 
        socket.join(chat_id); //CLIENT A JOINS ROOM//
    })

Client A joins room without problem, but how can i add also client B on same room ?

I haven't. Actually, i don't know how to use '.join' function with spesific 'socket.id' which i can obtain inside array. — Drierer Kas, Mar 16 '19 at 21:48
This may help: https://stackoverflow.com/questions/40367765/joining-socket-io-room-on-connect — , Mar 16 '19 at 21:56
This topic shows how to join a room properly. But my problem is, i can't join B user with A user's action :/ — Drierer Kas, Mar 17 '19 at 12:01
did you ever find a solution for this? i am facing same problem — 4308, Jul 15 '20 at 00:46

score 6 · Accepted Answer · answered Mar 19 '19 at 16:18

In io.on("connection") you can store socket object with user id as a object

{"socket": socket, "id": user_id}

to array. Then find index from array:

let user_index = users.findIndex(user => user.id == user_id);

And finally join to room.

let socketB = users[user_index].socket;
socketB.join('room');

ABC · Answer 2 · 2019-03-16T21:46:30.570

0

You can call join to subscribe the socket to a given channel:

// On connection join room
io.on('connection', function(socket){
  socket.join('ROOM ID');
});

And then simply use to or in (they are the same) when broadcasting or emitting:

io.to('some room').emit('some event');

To leave a channel you call leave in the same fashion as join.

Documentation: https://socket.io/docs/rooms-and-namespaces/

function join() {
 // Run's once clicked
 console.log('Join function here');
}

<a href="#" onclick="join()">Join</a>

edited Mar 16 '19 at 21:46

answered Mar 16 '19 at 21:40

ABC

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I have no problem for joining room on A side. The problem is, how can i join B user without any action after A user create and join that room ? – Drierer Kas Mar 17 '19 at 11:59

score 0 · Answer 3 · edited Mar 18 '19 at 16:44

0

Maybe handle it server side? Have a dictionary that stores User Ids and the Socket Id, you can store this information io.on("connection"). Then when User A does the process of creating the room, send to the server side the room id and something that identifies User B. Server side figures out the socket id of User B and joins them to the room.

edited Mar 18 '19 at 16:44

James Coyle

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answered Mar 18 '19 at 15:59

Steven Zhdanov

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I have an array that holds users and their socket id. So when user A create a room, i already know B's socket id. How can i join user B to that room ? User a join that room via socket.join('room'). Is that work like socketIDForB.join('room') ? – Drierer Kas Mar 19 '19 at 08:00

score 0 · Answer 4 · answered Sep 28 '20 at 06:56

This method is a bit of a hack, but it does allow you to force any specified socket into a room entirely server-side, once you have their socket ID, without maintaining another object array. SocketIO (v2.x) stores room allocations in two places to make things fun.

// $targetSocket is the socket ID of the connection you want to force into a room
    
$roomArray = $io->sockets->connected[$targetSocket]->rooms; //socket's rooms stored here
$roomArray[$newRoom] = $newRoom; // add the new room to this array
$io->sockets->connected[$targetSocket]->rooms = $roomArray; // save the modified array
$io->sockets->adapter->add($targetSocket, $newRoom); // update the adapter too

This is obviously PHP but it will translate easily into js.

You can do the reverse to kick users out of rooms too:

unset($roomArray[$oldRoom]); //delete room key and value from this socket's array
// save the array here, see above
$io->sockets->adapter->del($targetSocket, $oldRoom); // delete from adapter

Use both at once for a leave and join system.

This may seem pointless when a socket can add or remove itself so easily with socket->join('ROOM'); but there are circumstances in which you may need to do this from outside the connection's socket, such a game function.

Andrew Chamamme · Answer 5 · 2022-05-10T18:26:38.693

For anyone facing a similar issue.

@Kouvolan Arnold's solution will work but having to store the socket object for each user is too much of a resource, especially when socket.io already stores them.

A simple solution here is for you to get the socket object already stored by locating it. The good news is that socket.io already provides that, see below.

//v2.x or less
io.sockets.sockets[USER_SOCKET_ID_HERE]

//v3.x and 4.x
io.sockets.sockets.get(USER_SOCKET_ID_HERE)

The code below would have worked well in your case.

//v2.x or less
io.sockets.sockets[clientSocketId].join(roomid);

//v3.x and 4.x
io.sockets.sockets.get(clientSocketId).join(roomid);

Thanks

Socket.io join another client to a room

5 Answers5