function menuOpen(a) {
obj = document.getElementById(a);
if(obj){
obj.style.visibility="visible";
}
}

function menuClose(a) {
obj = document.getElementById(a);
if(obj){
obj.style.visibility="hidden";
}
}


function checkform_contact(f)
  {
 if (f.elements['voorletters'].value == "")
    {
    alert("Geen voorletters ingevoerd.");
    window.setTimeout("window.document.contact.elements['voorletters'].focus()",500);
    return (false);
    }
 if (f.elements['naam'].value == "")
    {
    alert("Geen achternaam ingevoerd.");
    window.setTimeout("window.document.contact.elements['naam'].focus()",500);
    return (false);
    }
  if (f.elements['adres'].value == "")
    {
    alert("Geen adres ingevoerd.");
    window.setTimeout("window.document.contact.elements['adres'].focus()",500);
    return (false);
    }
  if (f.elements['postcode'].value == "")
    {
    alert("Geen postcode ingevoerd.");
    window.setTimeout("window.document.mailfrm.elements['postcode'].focus()",500);
    return (false);
    }
  if (f.elements['woonplaats'].value == "")
    {
    alert("Geen woonplaats ingevoerd.");
    window.setTimeout("window.document.mailfrm.elements['woonplaats'].focus()",500);
    return (false);
    }
  if (f.elements['telefoon'].value == "")
    {
    alert("Geen telefoon ingevoerd.");
    window.setTimeout("window.document.contact.elements['telefoon'].focus()",500);
    return (false);
    }
  if (f.elements['email'].value == "")
    {
    alert("Geen e-mail ingevoerd.");
    window.setTimeout("window.document.contact.elements['email'].focus()",500);
    return (false);
    }
  if (f.elements['soortlid'].value == "")
    {
    alert("Vul in wat voor sort lid u bent AUB");
    window.setTimeout("window.document.contact.elements['email'].focus()",500);
    return (false);
    }
   else {
 	f.submit();
		}
  }


function checkform_ngf(f)
	{
	  if (f.elements['voornaam'].value == "")
		  {
		  alert("Vul uw voornaam in.");
		  window.setTimeout("window.document.submitform.elements['voornaam'].focus()",500);
		  return (false);
		}
	  if (f.elements['achternaam'].value == "")
		  {
		  alert("Vul uw achternaam in.");
		  window.setTimeout("window.document.submitform.elements['achternaam'].focus()",500);
		  return (false);
		}
	  if (f.elements['handicap'].value == "")
		  {
		  alert("Vul uw handicap in.");
		  window.setTimeout("window.document.submitform.elements['handicap'].focus()",500);
		  return (false);
		}
	  if (f.elements['loyalteenr'].value == "")
		  {
		  alert("Vul uw LoyalTee nummer in.");
		  window.setTimeout("window.document.submitform.elements['loyalteenr'].focus()",500);
		  return (false);
		}
	if (f.elements['ngfnummer'].value == "")
		  {
		  alert("Vul uw NGF nummer in.");
		  window.setTimeout("window.document.submitform.elements['ngfnummer'].focus()",500);
		  return (false);
		}
	  if (f.elements['email_adres'].value == "")
		  {
		  alert("Vul uw email_adres in.");
		  window.setTimeout("window.document.submitform.elements['email_adres'].focus()",500);
		  return (false);
		}
	  if (f.elements['telefoon'].value == "")
		  {
		  alert("Vul uw Telefoonnummer in.");
		  window.setTimeout("window.document.submitform.elements['telefoon'].focus()",500);
		  return (false);
		}
	  else {
		 f.submit();
			}
 	}

function submit_url() {
	var url = window.location.href;
	var url_naar = "http://www.golfbaan-zoetermeer.nl/send-friend/?link=" + url;
	//alert(url);
	//alert(url_naar);
	window.open(url_naar,null, 'height=320,width=514,status=yes,toolbar=no,menubar=no,location=no');
	//alert(url_naar);
	}