function zobrazit_tr()
{
  if (httpRequest.readyState == 4) {
    if(httpRequest.status == 200) {
      document.getElementById("ajax_treninky_div").innerHTML = httpRequest.responseText;
    } else {
      document.getElementById("ajax_treninky_div").innerHTML = "";
    }
  }
}

function ajax_treninky(druzstvo)
{
  var soubor = "/index/bottom_treninky.php";
  var parametr = "ajax_tr=x&druzstvo=" + druzstvo;

  if (window.ActiveXObject) {
    httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
  } else {
    httpRequest = new XMLHttpRequest();
  }

  httpRequest.open("POST", soubor, true);
  httpRequest.onreadystatechange= function () {zobrazit_tr(); } ;
  httpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  httpRequest.send(parametr);
}