function email_focus(obj) {
  if (obj.value == "Enter your email here")
    obj.value = "";
}
//------------------------------------------------------------------------------
function email_blur(obj) {
  if (obj.value == "")
    obj.value = "Enter your email here";
}
//------------------------------------------------------------------------------
function save_email(email) {
/*
  return 0 - subscribed successful
         1 - request failed
         2 - email invalid
         3 - database error
         4 - already subscribed
*/
  var req = createRequestObject();
  req.open("GET", "/register/subscribe.html?email=" + email, false);
  req.send(null);
  if (req.status == 200) {  
    return Number(req.responseText);    
  }
  else
    return 1;
}
//------------------------------------------------------------------------------
function subscribe() {
  var email = document.getElementById("email").value;

  if (!email || (email == "Enter your email here")) {
    alert("Please enter email address.");
  }  
  else if(!email.match(/\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/)) {  
    alert("The email address you typed is wrong. Please type a valid email and try again.");
  }
  else {
    var result = save_email(email);
    var msg = Array(
      "Thank you for signing up for our newsletter.",
      "Error occurred during request processing. Please try again.",
      "The email address you typed is wrong. Please type a valid email and try again.",
      "Database error occurred during saving you email. Please try again.",
      "Your email address is already signed up for our newsletter."
    );
    alert(msg[result]);
  }
}
//------------------------------------------------------------------------------