function checkUsername(isAsync)
{
  var req = null;
  var url = "signupCheck.php";
  var username = document.signup.newusername.value;
  var domainID = document.signup.domainlist.value;

  if (username == "")
  {
    return;
  }
  if (domainID == 0)
  {
    return;
  }

  if (window.XMLHttpRequest)
  {
    req = new XMLHttpRequest();
  }
  else if (window.ActiveXObject)
  {
    req = new ActiveXObject("Microsoft.XMLHTTP");
  }
  
  var paras = "domainID=" + domainID + "&username=" + username;

  if (req != null)
  {
    //req.open("GET", url + "?domainID=" + domainID + "&username=" + username, true);
    req.open("POST", url, isAsync);    

    req.onreadystatechange = 
	function() 
        {
          if (req.readyState == 4 && req.status == 200)
          {
            if (req.responseText)
            {
              statusProcess(req.responseText);
            }
          }
        }
   
    req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); 
    req.send(paras); 
  }
  else
  {
    alert('Your browswer does not support XMLHTTP');
  }
  //alert('req.responseText = ' + req.responseText);
  return req.responseText;
}


function statusProcess(status)
{
  if (status == "true")
  {
    alert('This username had been registered already with your domain preference, please use another username or domain name');
    document.signup.newusername.focus();
    return true;
  }
  else
  {
    return false;
  }
}