var xmlhttp;

//function showUser(str)
function showUser()
{
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }

var email = document.ajaxradioform.email.value; //gets email 
for (var i=0; i < document.ajaxradioform.myradio.length; i++)
   {
   if (document.ajaxradioform.myradio[i].checked)
      {
      var radiovalue = document.ajaxradioform.myradio[i].value; //gets radiovalue (either 'subscribe' or 'unsubscribe')
      }
   }

var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;

if ((!email) || (!email.match(emailExp))){
//	alert("Please enter a valid email!");
document.getElementById('mailerror').style.visibility = 'visible'; 
//document.ajaxradioform.email.value = "Please enter a valid email address";this is how you would replace the text - 
//a space saving alternative to the error message?
return false;
}
	
else
	{
document.getElementById('mailerror').style.visibility = 'hidden'; //hide the error message
document.getElementById('button').disabled=true; //disable the button
var t=setTimeout("document.getElementById('button').disabled=false", 5000);// re-enable the button after 5 seconds
var url="addtomailinglist.php";

url=url + "?radiovalue=" + radiovalue +"&email=" +email ;

url=url+"&sid="+Math.random();//prevents caching, info on w3schools
xmlhttp.onreadystatechange=stateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
	}
}

function stateChanged()
{
if (xmlhttp.readyState==4)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}