Socket.io 未向特定用户发送消息

Question

I have a chat app with node.js, socket io, and React.js. The issue: the private message featureis not working.

Client-side:

socket.emit("chat message private", { userIDtoReceiveTheMessage, msg });

Then my server will listen and emit to that specific user:

  socket.on("chat message private", ({ toUser, msg }) => {
    console.log(`from ${id} to ${toUser}: ${msg}`);
    let socketId = toUser;
    io.to(socketId).emit("private msg", msg);
  });

The result on the console for the server is: "from X to Y: message" (this is workings!)

My client should receive "msg", but nothing happens:

  useEffect(() => {
    socket.on("chat message", ({ nickname, msg }) => {
      setChat([...chat, { nickname, msg }]);
    });

    socket.on("private msg", (msg) => {
      console.log(msg);
      setChat([...chat, msg]);
    });

    return () => {
      socket.off();
    };
  }, [chat, toUser]);

Nothing shows up on the console for the specific user (or for any user).

PS: All other chat messages are being received in real-time. The only issue is with the ones using:

io.to(socketId).emit("private msg", msg);

Any suggestions?

Answer 1

Finally, I found the answer.

I am still trying to figure out the reason for this, but on the server, every new connection has 2 different ID's:

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

"socket" has:

• socket.client.id
• socket.id

To emit for a specific socket, the ID on this line:

io.to(socketId).emit("private msg", msg);

Needs to be the socket.id , and not the socket.client.id.

I was not able to find anything related to why every socket has 2 different ID's.