var url = "/alpha/include/check_url.php?param="; // The server-side script

function updateName() {
  // display a quick message while the script is being processed
  document.getElementById('un').innerHTML = "...checking for duplicates...";
  var check_url = document.getElementById("url").value;
  http.open("GET", url + check_url, true);
  http.onreadystatechange = handleHttpResponse;
  http.send(null);
}

function handleHttpResponse() {
  if (http.readyState == 4) {
    results = http.responseText;
    var check_url = document.getElementById("url").value;
    document.getElementById('un').innerHTML = results;
  }
}

function getHTTPObject() {
  var xmlhttp;
  /*@cc_on
  @if (@_jscript_version >= 5)
    try {
      xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
      try {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (E) {
        xmlhttp = false;
      }
    }

  @else
  xmlhttp = false;
  @end @*/
  if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
    try {
      xmlhttp = new XMLHttpRequest();
    } catch (e) {
      xmlhttp = false;
    }
  }
  return xmlhttp;
}
var http = getHTTPObject(); // We create the HTTP Object