function ajaxFunction(str)
{
var xmlhttp;
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else if (window.ActiveXObject)
  {
  // code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
else
  {
  alert("Your browser does not support XMLHTTP!");
  }

var url="reg_ip.php";
url=url+"?q="+str;
url=url+"&sid="+Math.random();

xmlhttp.open("GET",url,true);
xmlhttp.send(null);

}