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Node.js - Socket.io repeats the 'io.on('connection') over and over

So, I am still in the experimental phase of Socket.io, but I just can't figure out why my code is doing this. So, I have the code below and when I console.log the code, it repeats the the connection even when there is only one connection. Do you know a solution?
io.on('connnection', (socket) => {
console.log("A new user is connected.")
})
Client side:
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io()
</script>
Node.js Console:
A new user is connected.
A new user is connected.
A new user is connected.
A new user is connected.
A new user is connected.
A new user is connected.
A new user is connected.
...
(Note: there is only one connection, and I have already cleared the browser cashe)

Here are some of the possible reasons for socket.io connecting over and over:
Your socket.io client and server versions do not match and this causes a connection failure and an immediate retry.
You are running with some infrastructure (like a proxy or load balancer) that is not configured properly to allow lasting webSocket connections.
You are running a clustered server without sticky webSocket connections.
You have put the server-side io.on('connnection', ...) code inside some other function that is called more than once causing you to register multiple event handlers for the same event so you think you're getting multiple events, but actually you just have multiple listeners for the one occurrence of the event.
Your client code is calling its var socket = io() more than once.
Your client page is reloading (and thus restarting the connection on each reload) either because of a form post or for some other reason.
FYI, you can sometimes learn something useful by installing listeners for all the possible error-related events on both client and server connections and then logging which ones occur and any parameters that they offer. You can see all the client-related error events you can listen to and log here.

To solve repetion problem write your code like that for socket:
io.off("connnection").on('connnection', (socket) => {
console.log("A new user is connected.")
})

How to detect client disconnect from redis in nodejs?

I am using the library node_redis as the client for a micro-service message client that I am writing. Clients get messages from their application in their outbox that they need to send to other services. Everything is working great but I am trying to build some resilience on the part of the application that uses the redis client to communicate with the redis-server.
My idea is that the redis client-server connection status should be highly available to the clients. I mean that if a connection goes down, I would like to know within the second instead of the default timeout of 300 seconds. Currently I am using the free redislabs tier hosted on AWS, but I should be moving this to run in its own container on my kubernetes cluster.
I need to know the state of client connections in the network because I would like to not send messages when the network conditions are not right and not rely on the error handling to handle this sort of event. Knowing how often and when these high latency events occur will also help me diagnose and improve my network and my microservices.
Note: I wanted to set the connect_timeout value in the client options but this is listed as deprecated.

Something like that?
var redis = require('redis');
var client = redis.createClient();
var reconnectAfter = 15000;
client.on( 'error', function () {
console.log( (new Date()) + " Redis: disconnect");
setTimeout( connect, reconnectAfter);
});
connect = function(){
client = redis.createClient();
}

connection timeout OrientDB with Javascript API

In my webapp client side script I'm using the OrientDB Javascript API (orientdb-api.js). When the script initializes I run this code:
var orientdb = new ODatabase("http://localhost:2480/testapp");
var orientdbinfo = orientdb.open('root', 'admin');
This works fine and I can do all the various queries etc, as long as I don't wait more than 15 seconds between them. If I do, I get "error 401 (Unauthorised)" returned.
I know for a fact that this is the socket connection timing out. The timeframe matches the 15000ms timeout setting in the config. Also, as a test I've built a little button that calls the orientdb.open method above and reopens the connection. After I hit that button I can access the DB again.
Currently the queries and commands are being called directly in my script as I trigger actions from my web UI. Am I just being lazy and am I actually supposed to wrap every query in a function that tests the connection first and re-initializes if it is closed, or is there something I'm missing? If the former, what is an elegant way of coding that? If the latter, what am I missing?
To get around this I'm running a setInterval function that opens a new socket every 14 seconds. That will get me through my testing for sure, but I realise it's a hack.

When you start the OrientDB server, it creates two sockets: 2424 (binary) and 2480 (HTTP).
Because OrientJS uses the binary protocol, you need to connect to port 2424.
Try:
var orientdb = new ODatabase("http://localhost:2424/testapp");
var orientdbinfo = orientdb.open('root', 'admin');
And the socket should stay open (longer).

Node.js/Socket.io: Create a bot who's always in chat lobby/room, detecting specific activity and reporting to server?

I am running Node.js and Socket.io on Linux Server.
I've created an online chat room/lobby, I am wondering how can I create like a daemon who has a role of user, he is connected to lobby always and is monitoring lobby, and messages that users post. When specific criteria is matched - report back to server.
For example, some user posts too many messages per minute, the bot would send message to user saying to slow down, if user continues bot would send request to server saying to kick that user.
I am new to node.js and socket.io, so I am not sure how to implement it.
I don't want to hard code every rule or criteria into server itself.

I don't think your way will be working. The way on top of my head is doing it on server. Socket.io can fire any event on client side and send to server, so you can ask server to listen to certain event and handle your logics accordingly on server. Below is some sample code for your reference.
client side:
this event will fire whenever client sends a message.
$("#msgbutton").click(function(){
socket.emit("message","some message client send");
});
server side:
socket.on('message', function(msg){
var now = new Date();
var lastsent = socket.lastsent; //socket is an object and you can store lastsent datetime to it
var diff = now.getTime() - socket.lastsent.getTime();
if (diff/1000 > 2) // if message interval is larger than 2 seconds
{socket.to(room).emit('message',msg); // send message to whole room}
else if
{ // maybe send a warning event to user }
});
The code is not tested, and only consider the time difference between current msg and last message. If you want to monitor the message sent event over certain time course, you will have to write your logics on server to do that. Hope this can give you some pointers.

MQTT Js Last Will Message not getting published

I have the below code -->
var last_will = new Paho.MQTT.Message("last message");
last_will.destinationName = "Bridge123";
client = new Paho.MQTT.Client("broker.mqttdashboard.com", Number("8000"), "AX123");
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;
client.connect({onSuccess:onConnect} , {willMessage:last_will});
When i disconnect the client i expect a last will message being sent to the topic i have created .. Am using Paho 's mqtt version -3.1 .. Websockets are getting created fine but i do not see the last will message ...
Can anyone guide here ?
Adding the bigger picture :
I have a Python script p gathering current on / off status of a IOT device in the local environment and publishing to a topic "IOT1" over mqtt . I do not want the python script always running to get status from the IOT device as it overloads the device .. To solve this i am in need of finding active clients for "IOT1" topic so that i run or pause the thread sending requests to the IOT device in the local environment .. Is there a way other than the last will message to know this ?

Last Will and Testament messages are only published if client does not disconnect cleanly.
If you close the connection gracefully it will not be sent.
Only when the server fails to receive a message or ping packet in the time out period will the server send the message.

willMessage should be the property of the first object. See below code snippet.
client.connect({onSuccess:onConnect, willMessage:last_will});