To send a message to a particular client with socket.io and JavaScript, we use the join method.
For instance, we write
const socket = io.connect("http://localhost");
socket.emit("join", { email: "user1@example.com" });
to emit the join event on client side.
Then we write
const io = require("socket.io").listen(80);
io.sockets.on("connection", (socket) => {
socket.on("join", (data) => {
socket.join(data.email);
});
});
to listen to the join event with on and call join in the handler to add the client to the chat room.
Next, we write
io.sockets.in("user1@example.com").emit("new_msg", { msg: "hello" });
to call in to get the chat room and call emit to emit the new_msg event with the content on server side.
Then we write
socket.on("new_msg", (data) => {
console.log(data.msg);
});
to listen to the new_msg on client with on.
