Yes, you can create and test WebSocket applications on your localhost using XAMPP, but it requires some additional setup since XAMPP primarily serves HTTP requests. Here’s how you can do it:

Setting Up WebSockets with PHP

Install Required Libraries:
- You may need a WebSocket library for PHP. One popular option is Ratchet. You can install it using Composer.
- Make sure you have Composer installed. If not, download it from getcomposer.org.
Set Up Your Project:
- Navigate to your XAMPP htdocs directory and create a new project folder.
- Open a terminal/command prompt in that folder and run:
```
bash
composer require cboden/ratchet
```

Create a WebSocket Server:

Create a PHP file for your WebSocket server, e.g., server.php:

php
<?php
require 'vendor/autoload.php';

use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;

class MyWebSocket implements MessageComponentInterface {
    protected $clients;

    public function __construct() {
        $this->clients = new \SplObjectStorage;
    }

    public function onOpen(ConnectionInterface $conn) {
        $this->clients->attach($conn);
    }

    public function onMessage(ConnectionInterface $from, $msg) {
        foreach ($this->clients as $client) {
            if ($from !== $client) {
                $client->send($msg);
            }
        }
    }

    public function onClose(ConnectionInterface $conn) {
        $this->clients->detach($conn);
    }

    public function onError(ConnectionInterface $conn, \Exception $e) {
        $conn->close();
    }
}

$server = IoServer::factory(new HttpServer(new WsServer(new MyWebSocket())), 8080);
$server->run();

Run the WebSocket Server:
- In the terminal, navigate to your project directory and run:
```
bash
php server.php
```
- This will start the WebSocket server on port 8080.

Create a Client to Test the WebSocket:

Create an HTML file (e.g., client.html) in the same project folder:

html
<!DOCTYPE html>
<html>
<head>
    <title>WebSocket Test</title>
</head>
<body>
    <h1>WebSocket Test</h1>
    <input id="message" type="text" placeholder="Type a message">
    <button id="send">Send</button>
    <ul id="messages"></ul>

    <script>
        const conn = new WebSocket('ws://localhost:8080');

        conn.onopen = () => {
            console.log("Connection established!");
        };

        conn.onmessage = (event) => {
            const messages = document.getElementById('messages');
            const message = document.createElement('li');
            message.textContent = event.data;
            messages.appendChild(message);
        };

        document.getElementById('send').onclick = () => {
            const messageInput = document.getElementById('message');
            conn.send(messageInput.value);
            messageInput.value = '';
        };
    </script>
</body>
</html>

Open the Client:
- Open client.html in your web browser. You can open multiple tabs to see how messages are sent and received.

Testing Your WebSocket

With the server running, type a message in the input box and click the "Send" button. The message should appear in all connected clients.

Additional Notes

Make sure that the port (8080 in this example) is open and not blocked by a firewall.
For production, consider using a dedicated WebSocket server or a service like Pusher for scalability.

Feel free to ask if you need further assistance!