function chengcity(idostan,idcity)
{
document.getElementById("city").innerHTML="<img alt='چند لحظه...' height='11' src='../images/loading.gif' width='16'>";

if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("city").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","city.asp?ostan="+idostan+"&City="+idcity+"&sid="+Math.random(),true);
xmlhttp.send();
}