function GetXmlHttpObject(handler) {
    var objXmlHttp = null;

    if ( navigator.userAgent.indexOf("Opera") >=0 ) {
        alert("This example doesn't work in Opera");
        return;
    }

    if ( navigator.userAgent.indexOf("MSIE") >= 0 ) {
        var strName = "Msxml2.XMLHTTP";
        if ( navigator.appVersion.indexOf("MSIE 5.5") >=0 ) {
            strName = "Microsoft.XMLHTTP";
        }

        try {
            objXmlHttp = new ActiveXObject(strName);
            objXmlHttp.onreadystatechange = handler;
            return objXmlHttp;
        }
  					catch(e) {
            alert("Error. Scripting for ActiveX might be disabled");
            return;
        }
    }

    if ( navigator.userAgent.indexOf("Mozilla") >= 0 ) {
        objXmlHttp = new XMLHttpRequest();
        objXmlHttp.onload = handler;
        objXmlHttp.onerror = handler;
        return objXmlHttp;
    }
}

function cityChanged() {
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
       var towns = xmlHttp.responseText;
       eval(towns);
    }
}

function townChanged() {
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
       var shops = xmlHttp.responseText;
       eval(shops);
    }
}

function groupChanged() {
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
       var brands = xmlHttp.responseText;
	   eval(brands);
    }
}

function brandChanged() {
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
       var brands = xmlHttp.responseText;
       eval(brands);
    }

}

function show_town(val,referer) {
	//clear the drop-down menus:town and sales
	var a,b;
  
	for(a = document.getElementById("town").options.length - 1; a > 0; a--) {
        document.getElementById("town").options[a] = null;
    }
	
	for(b=document.getElementById("sales").options.length-1; b > 0; b--) {
		document.getElementById("sales").options[b] = null;
	}
	
	if ( (val.length > 0) && (referer.length > 0) ) {
		var url = "_bizeulasin_kod?referer="+referer+"&citycode="+val;
        xmlHttp = GetXmlHttpObject(cityChanged);
        xmlHttp.open("GET", url , true);
        xmlHttp.send(null);			
	}
}

function show_brand(val,referer) {
	var i;
	for(i = document.getElementById("brand").options.length - 1; i > 0; i--) {
        document.getElementById("brand").options[i] = null;
    }
	
	for(i = document.getElementById("model").options.length - 1; i > 0; i--) {
        document.getElementById("model").options[i] = null;
    }


	if ( (val.length > 0) && (referer.length > 0) ) {
		var url = "_bizeulasin_kod?referer="+referer+"&groupcode="+val;
		xmlHttp = GetXmlHttpObject(groupChanged);
        xmlHttp.open("GET", url , true);
        xmlHttp.send(null);
	}
}

function show_model(val,val2,referer) {
	var i;
    var combo_len = document.getElementById("model").options.length;
    for(i=document.getElementById("model").options.length-1; i > 0; i--) {
        document.getElementById("model").options[i]=null;
    }

	if ( (val.length > 0) && (referer.length > 0) ) {
		var url = "_bizeulasin_kod?referer="+referer+"&groupcode="+val+"&brandcode="+val2;
        xmlHttp = GetXmlHttpObject(brandChanged);
        xmlHttp.open("GET", url , true);
        xmlHttp.send(null);
	}
}

function show_shop(val,val2,referer) {
	var i;

	for(i=document.getElementById("sales").options.length-1; i > 0; i--) {
    	document.getElementById("sales").options[i]=null;
    }

	if ( (val.length > 0) && (referer.length > 0) ) {
		var url = "_bizeulasin_kod?referer="+referer+"&citycode="+val+"&towncode="+val2;
		xmlHttp = GetXmlHttpObject(townChanged);
        xmlHttp.open("GET", url , true);
        xmlHttp.send(null);
	}
}