codice:
function AjaxCall(AjaxForm, AjaxMethod, AjaxFile, AjaxHtml)
{
    var AjaxObject, AjaxText;
    AjaxText = document.getElementById(AjaxHtml);
    try
    {
        window.XMLHttpRequest ? AjaxObject = new XMLHttpRequest() : AjaxObject = new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (e)
    {
         AjaxText.innerHTML = "AJAX non funziona sul tuo browser";
    }
    AjaxObject.onreadystatechange = function()
    {
        if (AjaxObject.readyState == 4)
        {
            AjaxObject.status == 200 ? AjaxText.innerHTML = AjaxObject.responseText : AjaxText.innerHTML = "Si è verificato un errore nel tentativo di usare AJAX";
            document.body.style.cursor = "default";
        }
        else
        {
            document.body.style.cursor = "wait";
        }
    }
    AjaxObject.open(AjaxMethod, AjaxFile, true);
    if (AjaxMethod == "GET")
    {
        AjaxObject.send(); 
    }
    else
    {
        var AjaxCount = 0;
        var AjaxString = "";
        var AjaxForms = document.forms[AjaxForm];
        var AjaxElements = AjaxForms.elements.length;
        for (AjaxCount=0; AjaxCount<AjaxElements; AjaxCount++)
        {
            var AjaxType = AjaxForms.elements[AjaxCount].type.toLowerCase();
            if (AjaxType != "button" && AjaxType != "submit" && AjaxType != "image" && AjaxType != "reset")
            {
                if (AjaxType == "radio" || AjaxType == "checkbox")
                {
                    if (!AjaxForms.elements[AjaxCount].checked)
                    {
                        AjaxString += AjaxForms.elements[AjaxCount].value;
                    }
                }
                AjaxString += AjaxForms.elements[AjaxCount].name + "=" + encodeURIComponent(AjaxForms.elements[AjaxCount].value);
                if (AjaxCount < AjaxElements) AjaxString += "&";
            }
        }
        AjaxObject.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        AjaxObject.setRequestHeader("Content-length", AjaxString.length);
        AjaxObject.setRequestHeader("connection", "close");
        AjaxObject.send(AjaxString);
    }
}