function checkPackageDetails(package_name) {
  if(req.readyState == 4 || req.readyState == 0) {
    req.open("GET", "/cgi/package.php?package=" + package_name, true);
    req.setRequestHeader("Content-Type","text/plain");
    req.onreadystatechange = setPackageMsg;
    req.send(null);
  } else {
    alert("err");
  }
}

function setPackageMsg() {
  if(req.readyState == 4) {
    document.getElementById("details").innerHTML = req.responseText;
  }
}