function checkForm() {

with (document.forms['kontakt']) {
var alertMsg = "Following fields are required:\n";
var testradio = 0;
var x = 0;

if (k_tresc.value == "") alertMsg += "\nMessage";
if (k_kod.value == "") alertMsg += "\nKey";
if (k_firma.value == "") alertMsg += "\nCompany";
if (k_osoba.value == "") alertMsg += "\nName";

if (alertMsg != "Following fields are required:\n") {
alert(alertMsg);
return false;
} else {
return true;
} } 

}




function isNumber(str) {
  var r1 = new RegExp("^[0-9]+$");
  return (r1.test(str));
}