var xhr = false;
var ajaxcallback;
var ajaxpostdata;
var ajaxcallbackParam = false;


/**
 *xmlhhtp elvont megvalositasa
 */
function xmlhttp()
{
    try {
        xhr = new XMLHttpRequest();
    } 
    catch (error) {
        return false;
    }
    if (!xhr) {
        try {
            xhr = new ActiveXObject("Microsoft.XMLHTTP");
        } 
        catch (error) {
            return false;
        }
    }

}


function ajax(filename)
{
    xmlhttp();
    xhr.open("GET", filename);
    xhr.onreadystatechange = ajaxresponse;
    xhr.send(null);
}


function ajaxp(filename)
{
    xmlhttp();
    xhr.open("POST", filename);
    xhr.onreadystatechange = ajaxresponse;
    xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    xhr.send(ajaxpostdata);
    ajaxpostdata = '';
}


function ajaxresponse()
{
    if (xhr.readyState != 4) {
        return;
    }
    if (xhr.status == '200') {
        if (ajaxcallback) {
            if (ajaxcallbackParam) {
                ajaxcallback(ajaxcallbackParam);
            } else {
                ajaxcallback();
            }
        }
    } else {
        alert('Ajax hiba: ' + xhr.statusText);
    }
    return true;
}