function createAjaxObj() {
  var httprequest = false;
  if (window.XMLHttpRequest) { // если Mozilla, Safari
    httprequest = new XMLHttpRequest();
    if (httprequest.overrideMimeType) httprequest.overrideMimeType('text/xml');
  }
  else if (window.ActiveXObject) { // если IE
    try {
      httprequest = new ActiveXObject("Msxml2.XMLHTTP");
    } 
    catch (e){
      try{
        httprequest = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e){}
    }
  }
  return httprequest;
}

 function getTariff() {
    //var url = 'gettariff.php';
	var system_exchange = document.getElementById("system_exchange").value;
	var amount = document.getvaluta_form.amount1.value;
	var urlParams =  'utils/gettariff.php' + '?system_exchange=' + system_exchange  +'&amount=' + amount;
	//alert(urlParams);
	httprequest = createAjaxObj();
    httprequest.open("GET", urlParams, true);
	httprequest.onreadystatechange = updatePage2;
    httprequest.send(null);
 }
 
function updatePage1() {
	document.getvaluta_form.amount2.value = "Считаем!";
	document.getElementById("wait_calc").innerHTML = "<img src='/images/ajax_loader.gif' style='visibility:visible'>"
	document.getElementById("tariff_exchanger").innerHTML = "";
	document.getElementById("tariff_system").innerHTML = "";
	document.getvaluta_form.commission_exchanger.value = "";
	document.getvaluta_form.commission_system.value = "";
}
 
function updatePage2() {
	if (httprequest.readyState == 4){
		if (httprequest.status == 200){
			//alert("код: " + httprequest.status + " - " + httprequest.statusText);
			//alert (httprequest.responseText);
			var response = httprequest.responseText.split("|");
			//alert(response[0]);
			document.getvaluta_form.amount2.value = response[1]; //Выводим сумму с учетом тарифов
			document.getElementById("wait_calc").innerHTML = "<img src='/images/ajax_loader.gif' style='visibility:hidden'>";
			document.getElementById("tariff_exchanger").innerHTML = "(" + response[2] + "%)";
			document.getElementById("tariff_system").innerHTML = "(" + response[3] + "%)";
			document.getvaluta_form.commission_exchanger.value = response[4];
			document.getvaluta_form.commission_system.value = response[5];
			}
		else if (httprequest.status == 404)
			alert("Запрашиваемый URL не существует");
		else	
			alert("Ошибка: код " + httprequest.status);
		}		
}