var AJAXObject = CreateAjaxObject();

function CreateAjaxObject()
{
 var AJAXObject;
 var AppIdent = navigator.appName;

 if (AppIdent == "Microsoft Internet Explorer")
 {
  AJAXObject = new ActiveXObject("Microsoft.XMLHTTP");
 }
 else
 {
  AJAXObject = new XMLHttpRequest();
 }

 return AJAXObject;
}

function SendAjaxRequest(file, getRequestProc)
{
 AJAXObject.open('get', file);
 AJAXObject.onreadystatechange = getRequestProc;
 AJAXObject.send(null);
}

function getRequest()
{
  if (AJAXObject.readyState == 4)
  {
   var str = AJAXObject.responseText;
   
   var errors = 0;
   for (var i = 0; i < str.length; i++)
   {
    if (str.charAt(i) == 'f')
       errors++;
   }
   
   if (errors != 0)
   {
    alert("     ");
    document.regform.login.value = "";
    document.regform.login.focus();
   }
   else
   {
    alert("    ");
   }
  }
}

function CheckLogin()
{
 SendAjaxRequest('http://gold-wow.ru/check.php?login='+document.regform.login.value, getRequest);
}