function checkForm() {
  ImePrezime = document.getElementById("ImePrezime").value;
  firm = document.getElementById("firm").value;
  adresa = document.getElementById("adresa").value;
  telefon = document.getElementById("telefon").value;
  email = document.getElementById("emailfrom").value;
  subject = document.getElementById("subject").value;
  poruka = document.getElementById("poruka").value;
  
  if (ImePrezime == "") {
hideAllErrors();
document.getElementById("ImePrezimeError").style.display = "inline";
document.getElementById("ImePrezime").select();
document.getElementById("ImePrezime").focus();
  return false;
  } else if (firm == "") {
  hideAllErrors();
document.getElementById("firmError").style.display = "inline";
document.getElementById("firm").select();
document.getElementById("firm").focus();
  return false;
  } else if (adresa == "") {
hideAllErrors();
document.getElementById("adresaError").style.display = "inline";
document.getElementById("adresa").select();
document.getElementById("adresa").focus();
  return false;
} else if (telefon == "") {
hideAllErrors();
document.getElementById("telefonError").style.display = "inline";
document.getElementById("telefon").select();
document.getElementById("telefon").focus();
  return false;
} else if (email == "") {
hideAllErrors();
document.getElementById("emailfromError").style.display = "inline";
document.getElementById("emailfrom").select();
document.getElementById("emailfrom").focus();
  return false;
  } else if (poruka == "") {
hideAllErrors();
document.getElementById("subjectError").style.display = "inline";
document.getElementById("subject").select();
document.getElementById("subject").focus();
  return false;
  } else if (poruka == "") {
hideAllErrors();
document.getElementById("porukaError").style.display = "inline";
document.getElementById("poruka").select();
document.getElementById("poruka").focus();
  return false;
  }
  return true;
  }
 
  function hideAllErrors() {
document.getElementById("firmError").style.display = "none"
document.getElementById("ImePrezimeError").style.display = "none"
document.getElementById("adresaError").style.display = "none"
document.getElementById("telefonError").style.display = "none"
document.getElementById("emailfromError").style.display = "none"
document.getElementById("subjectError").style.display = "none"
document.getElementById("porukaError").style.display = "none" 
  }