var XMLHttp = getXMLHttp();

var b_num;

function get_link(block_num, dom) {
  
  b_num = block_num;

  XMLHttp.open("GET", dom + "/ajax_link.php?id=" + b_num, true);
  XMLHttp.onreadystatechange = handlerFunction;
  XMLHttp.send(null);
  document.getElementById("get_link_"+b_num).style.visibility = "hidden";
  document.getElementById("loader_img_"+b_num).style.visibility = "visible";
}

function handlerFunction() {
    
  if (XMLHttp.readyState == 4) {
    document.getElementById("download_" + b_num).innerHTML = XMLHttp.responseText;
    document.getElementById("loader_img_"+ b_num).style.visibility = "hidden";
  }
  else
    document.getElementById("get_link " + b_num).style.visibility = "visible";

}


function getXMLHttp() {
  if (window.XMLHttpRequest) {
  try {
  XMLHttp = new XMLHttpRequest();
  } catch (e) { }
  } else if (window.ActiveXObject) {
  try {
  XMLHttp = new ActiveXObject("Msxml2.XMLHTTP");
  } catch (e) {
  try {
  XMLHttp = new ActiveXObject("Microsoft.XMLHTTP");
  } catch (e) { }
  }
  }
  return XMLHttp;
}