A simple Socket.io test with client and server (Node.js) parts.

a-simple-socket-io-test.md

The client is a refactoring of the Websocket test found at: http://websocket.org/echo.html The server is a simple node.js Socket.io server which responds to the client's 'test' event, by responding with the client connection id.

See http://cliffordhall.com/2016/10/persistent-connections-with-socket-io/

package.json

{
  "name": "test-socket-io",
  "version": "1.0.0",
  "description": "Simple Socket.io client and server test",
  "main": "test-io-server.js",
  "dependencies": {
    "socket.io": "^1.5.0"
  },
  "author": "Cliff Hall",
  "license": "MIT",
  "homepage": "https://github.com/cliffhall/"
}

test-io-client.html

<!-- test-io-client.html -->
<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>
<script>

    function init()
    {
        output = document.getElementById("output");
        testSocket();
    }

    function testSocket()
    {
        var socket = io.connect('http://localhost:3000/');
        socket.on('test', onMessage );
        socket.on('connect', onConnect );
        socket.on('disconnect', onDisconnect );
        socket.on('connect_error', onError );
        socket.on('reconnect_error', onError );

        function onConnect(evt)
        {
            writeToScreen("CONNECTED");
            doSend("Allo?");
        }

        function onDisconnect(evt)
        {
            writeToScreen("DISCONNECTED");
        }

        function onMessage(data)
        {
            writeToScreen('<span style="color: blue;">RESPONSE: ' + data+'</span>');
            socket.close();
        }

        function onError(message)
        {
            writeToScreen('<span style="color: red;">ERROR:</span> ' + message);
        }

        function doSend(message)
        {
            writeToScreen("SENT: " + message);
            socket.emit('test', message);
        }

        function writeToScreen(message)
        {
            var pre = document.createElement("p");
            pre.style.wordWrap = "break-word";
            pre.innerHTML = message;
            output.appendChild(pre);
        }
    }

    window.addEventListener("load", init, false);
</script>

<h2>Socket.io Test</h2>

<div id="output"></div>

test-io-server.js

// test-io-server.js

// Create the socket server
const PORT = 3000;
var socket = require('socket.io')(PORT);
socket.on('connection', function(client) {

    // Listen for test and disconnect events
    client.on('test', onTest);
    client.on('disconnect', onDisconnect);

    // Handle a test event from the client
    function onTest(data) {
        console.log('Received: "' + data + '" from client: ' + client.id);
        client.emit('test', "Cheers, " + client.id);
    }

    // Handle a disconnection from the client
    function onDisconnect() {
        console.log('Received: disconnect event from client: ' + client.id);
        client.removeListener('test', onTest);
        client.removeListener('disconnect', onDisconnect);
    }
});

I tried ur sample i get "ERROR: Error: xhr poll error"