function ajax(target, action, step) {
  if (window.XMLHttpRequest) {
    req = new XMLHttpRequest();
  } else if (window.ActiveXObject) {
    req = new ActiveXObject("Microsoft.XMLHTTP");
  }
  if (req != undefined) {
    document.getElementById(target).innerHTML = '<img src="system/ajaxworking.gif" style="border:none;width:45px;height:5px;" alt="" />';
    req.onreadystatechange = function() {ajaxDone(target, action, step);};
    req.open("GET", '?ajax='+action, true);
    req.send("");
  }
}  

function ajaxDone(target, action, step) {
  if (req.readyState == 4) {
    if (req.status == 200) {
      var responseText = req.responseText;
      if (responseText != '') {
          document.getElementById(target).innerHTML = responseText;
          if (step == 1) {
            document.getElementById(target).style.display='none';
          }
      } else {
          alert("error");
      }
    }
  }
}