function tipfriend() {

    var band_id = document.getElementById('band_id').value;
    var friend_name = document.getElementById('friend_name').value;
    var friend_email = document.getElementById('friend_email').value;

    var your_name = document.getElementById('your_name').value;
    var opmerking = document.getElementById('opmerking').value;


    var parameters = 'band_id=' + band_id + '&friend_name=' + friend_name + '&friend_email=' + friend_email + '&your_name=' + your_name + '&opmerking=' + opmerking;

    var XMLHTTPObject = createHTTPHandler();
    XMLHTTPObject.open('GET', 'http://www.opzoeknaareenband.nl/content/actions/mail_to_friend.php?' + parameters, true);
    XMLHTTPObject.onreadystatechange = function() {
        if (XMLHTTPObject.readyState == 4) {
            var check_result = XMLHTTPObject.responseText;
            if (check_result > 0) {
                alert('Email is verzonden.');
            }
            else {
                alert('Email kon helaas niet verzonden worden. Probeer t opnieuw.' + check_result);
            }
        }
    }
    XMLHTTPObject.setRequestHeader("Cache-Control", "no-cache");
    XMLHTTPObject.setRequestHeader("X_USERAGENT", "MijnAjaxApplicatie");

    XMLHTTPObject.send(null);
}