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

var xhr;

function hotSet()
{
    if(xhr.readyState == 4 && xhr.status == 200)
    {
      document.getElementById('hot').innerHTML = xhr.responseText;
    }
}

function hotChange()
{
  xhr = createRequestObject();
  xhr.onreadystatechange = hotSet;
  xhr.open("get",'hotChange.php',true);
  xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
  xhr.send(null);
}