How can PHP scripts running on a web server access client-side system information, such as the currently logged-in user's username, in a secure and platform-independent way?

PHP scripts running on a web server cannot directly access client-side system information like the currently logged-in user's username due to security restrictions. One way to securely retrieve this information is to use client-side technologies like JavaScript to gather the data and send it to the server using AJAX requests. The server-side PHP script can then process the data received from the client-side and perform any necessary actions. 

// JavaScript code to retrieve the currently logged-in user's username
<script>
    var username = "<?php echo $_SESSION['username']; ?>";
    // Send the username to the server using AJAX
</script>

// PHP code on the server-side to process the received username
<?php
    $username = $_POST['username'];
    // Perform actions based on the received username
?>

Keywords

PHP web server client-side system information username

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