My own server client PHP

<?php

// Set up the server

$server = stream_socket_server("tcp://0.0.0.0:8080", $errno, $errorMessage);

if ($server === false) {

    throw new Exception($errorMessage);

}

// Wait for a client to connect

$client = stream_socket_accept($server);

// Read the request from the client

$request = fread($client, 1024);

echo "Request from client: " . $request . "\n";

// Send a response to the client

$response = "Hello from the server!";

fwrite($client, $response);

// Close the connection

fclose($client);

***********

//Set up the client

<button onclick="sendRequest()">Send request</button>

<script>

function sendRequest() {

    var xhttp = new XMLHttpRequest();

    xhttp.onreadystatechange = function() {

        if (this.readyState == 4 && this.status == 200) {

            alert(this.responseText);

        }

    };

    xhttp.open("POST", "server.php", true);

    xhttp.send("Hello from the client!");

}

</script>