Socket.IO duplicated message - node.js

Question

I'm trying to build a chat application using Laravel, with node js server, socketio and redis. What I have is this:
Client JS:
var socket = io('http://localhost:3005');
var room = '17';
$("#send").click(function(){
content = $("textarea").val();
id =$("#id").val();
$.ajax({
url: "{{route('send.message')}}",
method: "POST",
data: {content, id, room},
success: function(){
}
});
});
socket.on('cacad', function(message){
console.log(message); //multiple copies here
});
socket.on('connect', function(){
console.log("Connected!");
socket.emit('room', room);
});
Laravel Controller:
public function sendMessage(Request $request){
event(new EventName($request->all()));
$message = new Message;
$message->message = $request->content;
$redis = LRedis::connection();
$redis->publish('chat-channel', json_encode($request->all()));
$message->save();
}
Node Server:
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var redis = require('ioredis');
var myMessage;
var redis_client = redis.createClient();
redis_client.subscribe('chat-channel');
io.on('connection', function(socket) {
redis_client.on('message', function(channel, message) {
var myData = JSON.parse(message);
socket.broadcast.to('17').emit('cacad', 'u i u a a');
});
socket.on('room', function(room){
socket.join(room);
});
socket.on('disconnect', function(){
console.log("disconnected!");
});
});
http.listen(3005, function() {
console.log('Listening on Port 3005');
});
I am trying to broadcast a message u i u a a in room 17. But when I receive it in the console, it shows multiple copies of it, 2x-4x. In the Laravel controller I publish a message using redis and I subscribe to it in node server. It is received successfully, but the problem lies with the multiple copies of the message (client side).
Please where is it wrong? Thank you :)

Answer 1

I'm pretty convinced I found the issue although I had to search a bit about those simple API usage because I'm not using the library lately.
Looking at the docs it's explain your issue pretty clearly.
Here you are listening to a new connection,
io.on('connection', function(socket) {
If the client asked to join to a specific room, you join him:
socket.on('room', function(room){
socket.join(room);
So far it's like the docs:
io.on('connection', function(socket){
socket.join('some room');
});
But your issue is with your emit, on each client connection, you listen to a message from your redis. Then you broadcast it to the room with an emit of the connected client.
Instead of that, you can do this:
io.on('connection', function(socket) {
socket.on('room', function(room){
socket.join(room);
});
socket.on('disconnect', function(){
console.log("disconnected!");
});
});
redis_client.on('message', function(channel, message) {
var myData = JSON.parse(message);
io.to('17').emit('cacad', 'u i u a a');
});

Answer 2

I think this happens on the socket-io-client side. not on the server-side. when I was using react-js for the client-side. I received the same message multiple times.
with the same server, I imported socket-io-client 4.4.1 in the vanilla js front-end project. then I didn't get multiple messages... :)
try use latest socket io client versions. i think they have fixed the issue in the latest versions..