How can PHP developers ensure consistent behavior across different servers when handling AJAX requests?

To ensure consistent behavior across different servers when handling AJAX requests in PHP, developers can use the `$_SERVER['HTTP_X_REQUESTED_WITH']` header to check if the request was made using AJAX. This header is commonly set by most JavaScript libraries like jQuery when making AJAX requests. By checking for this header, developers can reliably determine if the request is an AJAX request and respond accordingly. 

if(isset($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
    // This is an AJAX request
    // Handle the AJAX request here
} else {
    // Not an AJAX request, handle accordingly
}

Keywords

PHP AJAX requests cross-server compatibility session management error handling

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