function GetXmlHttpObject()
{
  var xmlHttp=null;
  try
    {
    // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
    }
  catch (e)
    {
    // Internet Explorer
    try
      {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
      }
    catch (e)
      {
      xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
    }
  return xmlHttp;
}
function xmlhttpPost(strURL, strSubmit, strResultFunc) {
  xmlHttp=GetXmlHttpObject()
   xmlHttp.open('POST', strURL, true);
	xmlHttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
	xmlHttp.onreadystatechange = function() {
	if (xmlHttp.readyState == 4) {
           strResponse = xmlHttp.responseText;
           switch (xmlHttp.status) {
                   // Page-not-found error
                   case 404:
                           alert('Error: Not Found. The requested URL ' + 
                                   strURL + ' could not be found.');
                           break;
                   // Display results in a full window for server-side errors
                   case 500:
                           handleErrFullPage(strResponse);
                           break;
                   default:
                           // Call JS alert for custom error or debug messages
                           if (strResponse.indexOf('Error:') > -1 || 
                                   strResponse.indexOf('Debug:') > -1) {
                                   alert(strResponse);
                           }
                           // Call the desired result function
                           else {
                                   eval(strResultFunc + '(strResponse);');
                           }
                           break;
           }
   }
 }	
  xmlHttp.send(strSubmit);
}

function handleErrFullPage(strIn) {

        var errorWin;

        // Create new window and display error
        try {
                errorWin = window.open('', 'errorWin');
                errorWin.document.body.innerHTML = strIn;
        }
        // If pop-up gets blocked, inform user
        catch(e) {
                alert('An error occurred, but the error message cannot be' +
                        ' displayed because of your browser\'s pop-up blocker.\n' +
                        'Please allow pop-ups from this Web site.');
        }
}