$(document).ready(function(){


  $(".form-dotaz").submit(function(){
  
    var ok = true;
  
    if($("#jmeno").val() == ""){
      ok = false;
    }
    
    if($("#email").val() == ""){
      ok = false;
    }
    
    if($("#text-dotaz").val() == ""){
      ok = false;
    }
    
    
  
    if(ok){
      return true;
    }else{
      $("#form-error").fadeIn();
      return false;
    }
  
  });
  
});