Proper Socket.IO Latency Checking

client.js

/*
    - Insert this after including / referencing socket.io.min.js.
     
    - Point being:
      - Client sockets *naturally* adapts its Ping Interval & Ping Timeout
        from its server's settings, hence you can't actually those options here.
      - We instead add an eventhandler for the "pong", and the actual millisecond latency,
     	and optionally to the "ping" too, in case you wanna see it in action.
    
    - References:
      - Server API @ https://github.com/socketio/socket.io/blob/master/docs/API.md
      - Client API @ https://github.com/socketio/socket.io-client/blob/master/docs/API.md
*/


if(io){
	/* 
		Alternative:
	
		var HTTP_SERVER = "127.0.0.1"; // or "YourAwesomeDomainName.com"
		var HTTP_PORT 	= 3000;
		var socket 	= io(`http://${HTTP_SERVER}:${HTTP_PORT}/`);
		
	*/
	var CLIENT_SOCKET = io(`http://${window.location.host}/`);
		
	CLIENT_SOCKET.on('connect', function(){
		console.log(`Socket :: Connected.`);
	});
  
	CLIENT_SOCKET.on('disconnect', function(){
		console.log(`Socket :: Disconnected.`);
	});
	
	CLIENT_SOCKET.on('ping', function(){
		console.log(`Socket :: Ping sent.`);
	});
  
	CLIENT_SOCKET.on('pong', function(ms){
		console.log(`Socket :: Latency :: ${ms} ms`);
	});
	
}else{
	console.log("Error :: Socket IO not found!");
}

server.js

/*

    - Run w/ NodeJS
    - Needs:
      - Express (http://expressjs.com/
        - npm install express --save
      - Socket.IO
        - npm install socket.io --save
     
    - Point being:
      - We set "pingInterval" and "pingTimeout" in the options variable, 
        which is available upon creating a socket.io server instance.
      - Here we set the pingInterval to 2000, and the pingTimeout to 5000
        
    - References:
      - Server API @ https://github.com/socketio/socket.io/blob/master/docs/API.md
      - Client API @ https://github.com/socketio/socket.io-client/blob/master/docs/API.md
      
*/

var path 	= require('path');
var EXPRESS 	= require('express');
var HTTP 	= require('http');

var EXPRESS_INSTANCE 	= EXPRESS();
var HTTP_PORT 		= 3000;
var HTTP_SERVER 	= HTTP.Server(EXPRESS_INSTANCE);

/*
	This exposes the /static/ folder, since our files are hosted there.
	
	/sample-project-folder/
		- server.js
		- static
			- index.html
			- client.js
			- otherfileswhatever.js
	
	Change it as you like.
	
*/
EXPRESS_INSTANCE.use(EXPRESS.static(path.join(__dirname, './static/')));

HTTP_SERVER.listen(HTTP_PORT, function(){
  console.log(`HTTP_SERVER Listening on ${HTTP_PORT}`);
});



var SOCKET_IO_SERVER = require('socket.io')(
	HTTP_SERVER,
	{
		'pingInterval': 2000,
		'pingTimeout': 5000
	});

SOCKET_IO_SERVER.on('connection', function(CLIENT_SOCKET){
	
  console.log('A user connected');
  
  CLIENT_SOCKET.on('disconnect', function(){
    console.log('user disconnected');
  });
  
});

kl