function checkForm(formName)
{
  var form = document.getElementById(formName);
  var error = false;
  var errorMsg = "De volgende velden zijn niet (correct) ingevuld:\n";
  //if (form.companyName.value == null || form.companyName.value == "") { error = true; errorMsg += "\n- bedrijfsnaam"; }
  if (form.name.value    == null || form.name.value    == "") { error = true; errorMsg += "\n- Naam"; }
  //if (form.title.value    == null || form.title.value    == "") { error = true; errorMsg += "\n- Aanhef"; }
  if (form.phonenumber.value     == null || form.phonenumber.value     == "") { error = true; errorMsg += "\n- Telefoonnummer"; }
  if (form.from.value     == null || form.from.value     == "" || !checkEmail(form.from.value) ) { error = true; errorMsg += "\n- Email Adres"; }
  if (form.location.value        == null || form.location.value        == "") { error = true; errorMsg += "\n- Locatie"; }
  if (form.date.value       == null || form.date.value       == "" ) { error = true; errorMsg += "\n- Datum"; }
  if (form.time.value        == null || form.time.value        == "") { error = true; errorMsg += "\n- vragen/opmerkingen"; }
  if (form.comments.value        == null || form.comments.value        == "") { error = true; errorMsg += "\n- Opmerkingen"; }
   
  
  if (error) alert(errorMsg);
  else document.getElementById(formName).submit();
}

function checkEmail(address)
{
  var filter = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
  if (filter.test(address)) return true;
  else return false;
}