var request = null;
  var model_numb = null;

   function createRequest() {
     try {
       request = new XMLHttpRequest();
     } catch (trymicrosoft) {
       try {
         request = new ActiveXObject("Msxml2.XMLHTTP");
       } catch (othermicrosoft) {
         try {
           request = new ActiveXObject("Microsoft.XMLHTTP");
         } catch (failed) {
           request = null;
         }
       }
     }

     if (request == null)
       alert("Error creating request object!");
   }

function changeModel(brand) {
     createRequest();
     var url = "http://tyres.kiev.ua/published/SC/html/scripts/repo_themes/demo/automodel.php?model_num="+brand;
     var boardsSoldEl1 = document.getElementById("autoyear");
     boardsSoldEl1.innerHTML = "";
     var boardsSoldEl2 = document.getElementById("autosize");
     boardsSoldEl2.innerHTML = "";
     request.open("GET", url, true);
     request.onreadystatechange = updateModel;
     request.send(null);
}

function changeYear(model) {
     createRequest();
     var url = "http://tyres.kiev.ua/published/SC/html/scripts/repo_themes/demo/autoyear.php?model_num="+model;
     request.open("GET", url, true);
     request.onreadystatechange = updateYear;
     model_numb = model;
     request.send(null);
}

function changeSize(year) {
     createRequest();
     var url = "http://tyres.kiev.ua/published/SC/html/scripts/repo_themes/demo/autosize.php?model_num="+model_numb+"&year_num="+year;
     request.open("GET", url, true);
     request.onreadystatechange = updateSize;
     request.send(null);
}

  function updateSize() {
    if (request.readyState == 4) {
      if(request.status == 200) {
      var newTotal = request.responseText;
      var boardsSoldEl = document.getElementById("autosize");
      boardsSoldEl.innerHTML = newTotal;
      }
    }
  }


  function updateYear() {
    if (request.readyState == 4) {
       if(request.status == 200) {
     var newTotal = request.responseText;
      var boardsSoldEl = document.getElementById("autoyear");
      boardsSoldEl.innerHTML = newTotal;
      var boardsSoldEl1 = document.getElementById("autosize");
      boardsSoldEl1.innerHTML = "";
 }
  }
  }


  function updateModel() {
    if (request.readyState == 4) {
      if(request.status == 200) {
      var newTotal = request.responseText;
      var boardsSoldEl = document.getElementById("automodel");
      boardsSoldEl.innerHTML = newTotal;
  }
   }
  }

   function getautobrand() {
     createRequest();
     var url = "http://tyres.kiev.ua/published/SC/html/scripts/repo_themes/demo/autobrand.php";
     var boardsSoldEl = document.getElementById("automodel");
     boardsSoldEl.innerHTML = "";
     var boardsSoldEl1 = document.getElementById("autoyear");
     boardsSoldEl1.innerHTML = "";
     var boardsSoldEl2 = document.getElementById("autosize");
     boardsSoldEl2.innerHTML = "";

     request.open("GET", url, true);
     request.onreadystatechange = updateBrand;
     request.send(null);
  }

  function updateBrand() {
    if (request.readyState == 4) {
       if(request.status == 200) {
     var newTotal = request.responseText;
      var boardsSoldEl = document.getElementById("autobrand");
      boardsSoldEl.innerHTML = newTotal;
      var boardsSoldEl2 = document.getElementById("autosize");
     boardsSoldEl2.innerHTML = "";
  }
   }
  }

 function replaceText(el, text) {
  if (el != null) {
    clearText(el);
    var newNode = document.createTextNode(text);
    el.appendChild(newNode);
  }
}

function clearText(el) {
  if (el != null) {
    if (el.childNodes) {
      for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        el.removeChild(childNode);
      }
    }
  }
}

function getText(el) {
  var text = "";
  if (el != null) {
    if (el.childNodes) {
      for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        if (childNode.nodeValue != null) {
          text = text + childNode.nodeValue;
        }
      }
    }
  }
  return text;
}