function ajax(page, target)
{
    var httpRequest;
    if(typeof window.ActiveXObject != 'undefined')
    {
        httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else
    {  
        httpRequest = new XMLHttpRequest();
    }
    httpRequest.open("GET", page, true);
    httpRequest.onreadystatechange = function() 
    {
        processRequest(httpRequest, target) 
    };
    httpRequest.send(null);
}

function processRequest(httpRequest, target) 
{
    if (httpRequest.readyState == 4)
    {
        if (( httpRequest.status >= 200 && httpRequest.status < 300 ) || httpRequest.status == 304)
        {
            if (typeof target == 'string') 
            {
                document.getElementById(target).innerHTML = httpRequest.responseText;
            }
            if (typeof target == 'function') 
            {
                target(httpRequest.responseText);
            }
        }
        else
        {
	if(httpRequest.status == 404) {
		document.getElementById(target).innerHTML = 'Chyba: Stránka nenalezena';
	}
	else {
            document.getElementById(target).innerHTML = 'Chyba: ' + httpRequest.status + ' - ' + httpRequest.statusText;
	}
        }
    }
}