// Hidden Iframe
function createIframe() {
  var iframe = document.createElement("iframe");
  iframe.id = "hiddenFrame"
  iframe.style.border = "0px";
  iframe.style.width = "0px";
  iframe.style.height = "0px";
  document.body.appendChild(iframe);
}

function formChecker() {
  emailRe = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*\.(\w{2}|(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum))$/
  if(document.getElementById('first_name').value == '') {
    alert('Please enter your first name.');
  } else if(document.getElementById('last_name').value == '') {
    alert('Please enter your last name.');
  } else if(document.getElementById('email').value == '') {
    alert('Please enter your e-mail.');
  } else if(!emailRe.test(document.getElementById('email').value)) {
    alert('Invalid e-mail, please re-enter your email');
  } else {
    alert('Congradulations! You have successfully subscribed to our newsletter.');
    addSubscriber(); 
  }
}

function addSubscriber() {
  var lastName = document.getElementById("last_name").value;
  var firstName = document.getElementById("first_name").value;
  var email = document.getElementById("email").value;
  frames[2].location = "../add_subscriber.php?first_name=" + firstName + "&last_name=" + lastName + "&email=" + email;
  document.getElementById("last_name").value = "";
  document.getElementById("first_name").value = "";
  document.getElementById("email").value = "";
}