Socket.IO 1.0.x: Get socket by id

Version 3.0.3

// in "of", you can put '/' or whatever namespace you're using
    
io.of('/').sockets.get(socketId)

Basically, sockets is no longer a simple Object. It's a Map, so you have to use .get().

For socket.io 1.0 use:

io.sockets.connected[socketId]

For 0.9 its io.sockets.sockets[socketId] and not io.sockets.socket[socketId]

you can also use like:

io.to(socketid).emit();

Socket.io Version 4.0.0

io.sockets.sockets.get(socketId);