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Rooms allow simple partitioning of the connected clients. This allows events to be emitted to subsets of the connected client list, and gives a simple method of managing them.

Joining and Leaving

Joining a named room is achieved by calling the join() function on a connected socket object.

socket.join('room')

Leaving a room is achieved by calling the leave() function on a connected socket object.

socket.leave('room')

A simple subscribe/unsubscribe system can be built very quickly.

socket.on('subscribe', function(data) { socket.join(data.room); })

socket.on('unsubscribe', function(data) { socket.leave(data.room); })

Note that it is not necessary to call socket.leave() during the disconnect event. This will happen automatically. Empty rooms will be automatically pruned so there is no need to manually remove them.

Emitting to a room

There are two ways for emitting to a room: either using socket.broadcast.to('room') or io.sockets.in('room').

Socket Broadcast

Broadcasts are sent from a socket object and are received by all clients in the room except for the emitting socket

io.sockets.on('connection', function (socket) {
  socket.broadcast.to('room').emit('event_name', data) //emit to 'room' except this socket
})

A broadcast is sent to all sockets except for the emitting one if a room is not specified

io.sockets.on('connection', function (socket) {
  socket.broadcast.emit('event_name', data) //emit to all sockets except this one
})

Io Sockets

Emitting an event to all clients in a particular room

io.sockets.in('room').emit('event_name', data)

Emitting an event to all clients

io.sockets.emit('event_name', data)

Emitting an event to all clients in a namespace of a particular room

io.of('namespace').in('room').emit('event_name', data)

Getting information about rooms

All rooms

A list of all rooms can be found by looking in io.sockets.manager.rooms. This is a hash, with the room name as a key to an array of socket IDs. Note that the room names will have a leading / character. This is used internally and does not have to be referenced when joining, leaving or emitting to rooms.

Clients in a room

If you want a list of clients in a particular room, call io.sockets.clients('room'). This will return Socket instances of all clients in the room.

For namespaces call io.of('namespace').clients('room')

Rooms a client has joined

You can get a dictionary of rooms a particular client socket has joined by looking in io.sockets.manager.roomClients[socket.id]. Again, the room name will have a leading / character, but the name with and without the leading '/' will be in the dictionary, and their values will be true.

It is important to note that all clients are automatically joined to a room with a blank name. This is a catch-all room that contains a list of all connected clients. It will show up as a key with a value of "" in lists of room names.

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