function checkEnter(e){
	var characterCode;
	if(e && e.which){
		e = e;
		characterCode = e.which;
	}
	else{
		e = event;
		characterCode = e.keyCode;
	}	 
	if(characterCode == 13){
		MakeRequest();
		return false;
	}
	else{
		return true;
	}
}

function getXMLHttp()
{
  var xmlHttp

  try
  {
    //Firefox, Opera 8.0+, Safari
    xmlHttp = new XMLHttpRequest();
  }
  catch(e)
  {
    //Internet Explorer
    try
    {
      xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch(e)
    {
      try
      {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch(e)
      {
        return false;
      }
    }
  }
  return xmlHttp;
}

function MakeRequest()
{
  var xmlHttp = getXMLHttp();
  
  xmlHttp.onreadystatechange = function()
  {
    if(xmlHttp.readyState == 4)
    {
      HandleResponse(xmlHttp.responseText);
    }
  }
  // Get email address from form field contents
  var email = document.registerEmail.email_address.value;

  // Pass them to external server.
  xmlHttp.open("GET", "register_email.php?e=" + email, true); 
  xmlHttp.send(null);
}

function HandleResponse(response)
{
  document.getElementById('email_registration').innerHTML = response;
}