function checkNick(){
  nick=document.getElementById('nick');
  nickError=document.getElementById('nickError');
  
  if(nick.value.length < 3){
          nickError.innerHTML="Přezdívka musí mít minimálně 3 znaky";
          
          nick.style.background="#FFE2E2";
      return false;
  } else{
          nickError.innerHTML="";
          nick.style.background="#FFFFFF";
      return true;
    }
}

function checkFavourite(){
  favourite=document.getElementById('favourite');
  favouriteError=document.getElementById('favouriteError');

  if(favourite.value == ''){
          favouriteError.innerHTML="Vyberte nejoblíbenější";
          favourite.style.background="#FFE2E2";
      return false;
  } else{
          favouriteError.innerHTML="";
          favourite.style.background="#FFFFFF";
      return true;
    }
}

function checkMsg(){
  msg=document.getElementById('msg');
  msgError=document.getElementById('msgError');
  
  if(msg.value == "Váš vzkaz" || msg.value.length < 6){
          msgError.innerHTML="Vyplňte vzkaz (Nejméně 6 znaků)";
          msg.style.background="#FFE2E2";
      return false;
  } else{
          msgError.innerHTML="";
          msg.style.background="#FFFFFF";
      return true;    
    }
}

function clearMsg(){
  document.getElementById('msg').value='';
  document.getElementById('msg').onfocus=null;
}

function checkForm(){
  if (checkNick() && checkFavourite() && checkMsg() ) {
  return true;
  } else {
  alert("Vyplňte všechny povinné položky.");

  return false;}
}

function resetForm() {
  document.getElementById('nickError').innerHTML = "";
  document.getElementById('nick').style.background="#FFFFFF";
  
  document.getElementById('favouriteError').innerHTML = "";
  document.getElementById('favourite').style.background="#FFFFFF";
  
  document.getElementById('msgError').innerHTML = "";
  document.getElementById('msg').style.background="#FFFFFF";
}