var mailpopupvisible = false;

function toggleMailPopup()
{
  var popup = document.getElementById("mailPopUp");

  if (mailpopupvisible)
  {
    popup.style.display = "none";
    mailpopupvisible = false;
  }
  else
  {
    popup.style.display = "block";
    mailpopupvisible = true;
  }
}

function check_email(e)
{
  ok = "1234567890qwertyuiop[]asdfghjklzxcvbnm.@-_QWERTYUIOPASDFGHJKLZXCVBNM";

  for(i=0; i < e.length ;i++)
  {
    if(ok.indexOf(e.charAt(i))<0)
      return false;
  }

  if (document.images)
  {
    re = /(@.*@)|(\.\.)|(^\.)|(^@)|(@$)|(\.$)|(@\.)/;
    re_two = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/;
    if (!e.match(re) && e.match(re_two))
      return true;
  }
}

function checkMailAFriendForm()
{
  var errormsg = "";

  if (document.getElementById("senderName").value == "")
    errormsg += "\n- 'Uw naam' is een verplicht veld";

  var senderEmail = document.getElementById("senderEmail").value;
  if (senderEmail == "")
  {
    errormsg += "\n- 'Uw e-mailadres' is een verplicht veld";
  }
  else
  {
    var correctemail = check_email(senderEmail);
    if (!correctemail)
      errormsg += "\n- 'Uw e-mailadres' bevat een ongeldig e-mailadres";
  }

  if (errormsg != "")
  {
    errormsg = "Een of meer velden zijn niet correct ingevuld:\n" + errormsg;
    alert(errormsg);
    return false;
  }
  else
  {
    document.getElementById("mailPopUp").style.display = "none";
    return true;
  }
}