这里是一个更完整的答案，关于从0.9改变了什么。X到1.x。

 // send to current request socket client
 socket.emit('message', "this is a test");// Hasn't changed

 // sending to all clients, include sender
 io.sockets.emit('message', "this is a test"); // Old way, still compatible
 io.emit('message', 'this is a test');// New way, works only in 1.x

 // sending to all clients except sender
 socket.broadcast.emit('message', "this is a test");// Hasn't changed

 // sending to all clients in 'game' room(channel) except sender
 socket.broadcast.to('game').emit('message', 'nice game');// Hasn't changed

 // sending to all clients in 'game' room(channel), include sender
 io.sockets.in('game').emit('message', 'cool game');// Old way, DOES NOT WORK ANYMORE
 io.in('game').emit('message', 'cool game');// New way
 io.to('game').emit('message', 'cool game');// New way, "in" or "to" are the exact same: "And then simply use to or in (they are the same) when broadcasting or emitting:" from http://socket.io/docs/rooms-and-namespaces/

 // sending to individual socketid, socketid is like a room
 io.sockets.socket(socketid).emit('message', 'for your eyes only');// Old way, DOES NOT WORK ANYMORE
 socket.broadcast.to(socketid).emit('message', 'for your eyes only');// New way

我想编辑@soyuka的帖子，但我的编辑被同行评审拒绝了。

来自@LearnRPG的答案，但带有1.0:

 // send to current request socket client
 socket.emit('message', "this is a test");

 // sending to all clients, include sender
 io.sockets.emit('message', "this is a test"); //still works
 //or
 io.emit('message', 'this is a test');

 // sending to all clients except sender
 socket.broadcast.emit('message', "this is a test");

 // sending to all clients in 'game' room(channel) except sender
 socket.broadcast.to('game').emit('message', 'nice game');

 // sending to all clients in 'game' room(channel), include sender
 // docs says "simply use to or in when broadcasting or emitting"
 io.in('game').emit('message', 'cool game');

 // sending to individual socketid, socketid is like a room
 socket.broadcast.to(socketid).emit('message', 'for your eyes only');

为了回答@Crashalot的评论，socketid来自:

var io = require('socket.io')(server);
io.on('connection', function(socket) { console.log(socket.id); })

其他情况下

io.of('/chat').on('connection', function (socket) {
    //sending to all clients in 'room' and you
    io.of('/chat').in('room').emit('message', "data");
};

V4.x中的服务器端所有有效发射事件列表

io.on("connection", (socket) => {

// basic emit
socket.emit(/* ... */);

// to all clients in the current namespace except the sender
socket.broadcast.emit(/* ... */);

// to all clients in room1 except the sender
socket.to("room1").emit(/* ... */);

// to all clients in room1 and/or room2 except the sender
socket.to(["room1", "room2"]).emit(/* ... */);

// to all clients in room1
io.in("room1").emit(/* ... */);

// to all clients in room1 and/or room2 except those in room3
io.to(["room1", "room2"]).except("room3").emit(/* ... */);

// to all clients in namespace "myNamespace"
io.of("myNamespace").emit(/* ... */);

// to all clients in room1 in namespace "myNamespace"
io.of("myNamespace").to("room1").emit(/* ... */);

// to individual socketid (private message)
io.to(socketId).emit(/* ... */);

// to all clients on this node (when using multiple nodes)
io.local.emit(/* ... */);

// to all connected clients
io.emit(/* ... */);

// WARNING: `socket.to(socket.id).emit()` will NOT work, as it will send to everyone in the room
// named `socket.id` but the sender. Please use the classic `socket.emit()` instead.

// with acknowledgement
socket.emit("question", (answer) => {
    // ...
});

// without compression
socket.compress(false).emit(/* ... */);

// a message that might be dropped if the low-level transport is not writable
socket.volatile.emit(/* ... */);

});

客户端

// basic emit
    socket.emit(/* ... */);

// with acknowledgement
    socket.emit("question", (answer) => {
        // ...
    });

// without compression
    socket.compress(false).emit(/* ... */);

// a message that might be dropped if the low-level transport is not writable
    socket.volatile.emit(/* ... */);

存档链接到source => http://archive.today/2021.06.22-023900/https://socket.io/docs/v4/emit-cheatsheet/index.html

以下是我的列表(1.0版本更新):

// sending to sender-client only
socket.emit('message', "this is a test");

// sending to all clients, include sender
io.emit('message', "this is a test");

// sending to all clients except sender
socket.broadcast.emit('message', "this is a test");

// sending to all clients in 'game' room(channel) except sender
socket.broadcast.to('game').emit('message', 'nice game');

// sending to all clients in 'game' room(channel), include sender
io.in('game').emit('message', 'cool game');

// sending to sender client, only if they are in 'game' room(channel)
socket.to('game').emit('message', 'enjoy the game');

// sending to all clients in namespace 'myNamespace', include sender
io.of('myNamespace').emit('message', 'gg');

// sending to individual socketid
socket.broadcast.to(socketid).emit('message', 'for your eyes only');

// list socketid
for (var socketid in io.sockets.sockets) {}
 OR
Object.keys(io.sockets.sockets).forEach((socketid) => {});

广播。Emit将MSG发送到所有其他客户端(发送方除外)

socket.on('cursor', function(data) {
  socket.broadcast.emit('msg', data);
});