'how to get socket.io number of clients in room?

my socket.io version 1.3.5

I want to get number of clients in particular room.

This is my code.

 socket.on('create or join', function (numClients, room) {
            socket.join(room);
    });

I use this code for get clients in room :

console.log('Number of clients',io.sockets.clients(room));

Solution 1:^[1]

This works for version 3

io.sockets.adapter.rooms.get(roomName).size

Solution 2:^[2]

To get the number of clients in a room you can do the following:

    function NumClientsInRoom(namespace, room) {
      var clients = io.nsps[namespace].adapter.rooms[room];
      return Object.keys(clients).length;
    }

This variable clients will hold a object where each client is a key. Then you just get the number of clients (keys) in that object.

If you haven't defined a namespace the default one is "/".

Solution 3:^[3]

Have a counter variable to keep count, increase when someone joins and decrease when people disconnect.

io.on('connection', function (socket) {

var numClients = {};

socket.on('join', function (room) {
    socket.join(room);
    socket.room = room;
    if (numClients[room] == undefined) {
        numClients[room] = 1;
    } else {
        numClients[room]++;
    }
});

socket.on('disconnect', function () {
     numClients[socket.room]--;
});

Solution 4:^[4]

This work for me.

// check if your room isn't undefined.
if (io.sockets.adapter.rooms['your room name']) 
{
   // result
   console.log(io.sockets.adapter.rooms['your room name'].length);
}

Solution 5:^[5]

this work for me

io.in('yourRoom').allSockets().then(result=>{
    console.log(res.size) })

Solution 6:^[6]

In socket.io ^1.4.6

function numClientsInRoom(namespace, room) {
    var clients = io.nsps[namespace].adapter.rooms[room].sockets;
    return Object.keys(clients).length;
}

You need to add .sockets to rooms[room], because variable clients holds all connection inside sockets variable.

Solution 7:^[7]

i'm a bit late to the party, but I found a valid solution:

io.in('YOUR_ROOM').engine.clientsCount;

Solution 8:^[8]

socket.io's rooms is a Map whose elements map to Sets.

You use get(roomId) to get the value of that roomId in a Map and you use .size to the number of elements in a set unlike .length for number of elements in an array.

socket.on("join-room",roomId => {
    const room = io.of("/yourNameSpace").adapter.rooms.get(roomId)
     if(room === undefined || room.size < 2) {
       socket.join(roomId)
     }else {
       io.of("/yourNameSpace").emit("can't join link")
     }
  })

Solution 9:^[9]

io.nsps['/'].adapter.rooms['your room name'].sockets;

If your namespace is not /, change it.

Solution 10:^[10]

Only one that worked for me in 2022 using socket.io 4.5.1:

io._nsps.get('/').adapter.rooms.get('your-room-id').size;

Thanks to @Abhishek Kumar, just making a top level comment for visibility.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Parag Jain
Solution 2
Solution 3
Solution 4
Solution 5	jalal
Solution 6	Woolfi182
Solution 7	Dharman
Solution 8	user3840170
Solution 9	Mario Varchmin
Solution 10	Joe Roddy

'how to get socket.io number of clients in room?

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]

Solution 6:[6]

Solution 7:[7]

Solution 8:[8]

Solution 9:[9]

Solution 10:[10]