io.emit vs socket.emit

Question

I'm new to socket.io and have run in to something that seems pretty weird. I don't actually know the difference between socket.emit and io.emit but I can't find an explanation anywhere.

io.on('connection', function(socket){   io.emit('connected')  // <<<< HERE >> socket.emit('connected');   socket.on('disconnect', function(){     io.emit('disconnect')   });   socket.on('chat message', function(msg){     io.emit('chat message', msg);   }); });  server.listen(3000); 

That's my server stuff however when I change the io to socket that message only gets displayed when the user who is connecting connects. io.emit sends the message to all users.

Maybe it's supposed to be like that or maybe its just some horrible hack? Let me know if you need the client side HTML.

Answer 1

Here's a supplementary documentation for reference :

socket.emit('message', "this is a test"); //sending to sender-client only  socket.broadcast.emit('message', "this is a test"); //sending to all clients except sender  socket.broadcast.to('game').emit('message', 'nice game'); //sending to all clients in 'game' room(channel) except sender  socket.to('game').emit('message', 'enjoy the game'); //sending to sender client, only if they are in 'game' room(channel)  socket.broadcast.to(socketid).emit('message', 'for your eyes only'); //sending to individual socketid  io.emit('message', "this is a test"); //sending to all clients, include sender  io.in('game').emit('message', 'cool game'); //sending to all clients in 'game' room(channel), include sender  io.of('myNamespace').emit('message', 'gg'); //sending to all clients in namespace 'myNamespace', include sender  socket.emit(); //send to all connected clients  socket.broadcast.emit(); //send to all connected clients except the one that sent the message  socket.on(); //event listener, can be called on client to execute on server  io.sockets.socket(); //for emiting to specific clients  io.sockets.emit(); //send to all connected clients (same as socket.emit)  io.sockets.on() ; //initial connection from a client. 

Hope this helps!.

Answer 2

The io variable represents the group of sockets. The code you have starts on line one with providing a function in the second parameter that gives you a socket variable every time a new connection is made. The socket variable is only for communicating with each individual connection. You may not see it in the code but there will be one socket variable for each connection established