function checkForm (em, cont) {

  if (em.value.length === 0) {
    window.alert("Zadejte svou emailovou adresu.");
    em.focus();
    return false;
  }

  if (validate_email(em.value) === false) {
    window.alert("Zadejte platnou emailovou adresu.");
    em.focus();
    return false;
  }
  
  if (cont.value.length === 0) {
    window.alert("Vyplňte text dotazu.");
    cont.focus();
    return false;
  }

  
  $.ajax({
    type: "POST",
    url: "email",
    dataType: "html",
    data: "email=" + em.value + "&dotaz=" + cont.value,
    success: function(response) {
      if (response.substr(0,1) == "0") {
        var field = $('#fff');
        field.fadeOut("normal", function() {
          field.html( "<div id=\"ajaxMessage\">" + response.substr(1) + "</div>" );
          field.fadeIn();
        });
      }
      else
        window.alert(response);
    }
  });
  
  return false;

}


function validate_email (str) {
  var apos = str.indexOf("@");
  var dotpos = str.lastIndexOf(".");
  if (apos < 1 || dotpos-apos < 2)
    return false;
  else
    return true;
}