var ajaxCall;

function getAjaxRequest()
{	
	var xmlHttp = false;
	try
	{
	  xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch (e)
	{
	  try
	  {
	    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
	  }
	  catch (e2)
	  {
	    xmlHttp = false;
	  }
	}
	
	if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
	  xmlHttp = new XMLHttpRequest();
	}
	
	return xmlHttp;
}

function tracker(webContext, portalName, trackerType, param1, param2, param3, param4)
{
    //default the params if empty
    if (param1 == undefined)
        param1="";
    if (param2 == undefined)
        param2="";
    if (param3 == undefined)
        param3="";
    if (param4 == undefined)
        param4="";
        
    var ajaxTrackerCall = getAjaxRequest();
    var ajaxTrackerUrl = webContext +"/ajaxAction.run?function=tracker"
                  +"&pname=" +portalName 
                  +"&trktyp=" +trackerType 
                  +"&trkprm1=" +param1 
                  +"&trkprm2=" +param2 
                  +"&trkprm3=" +param3 
                  +"&trkprm4=" +param4 
                  +"&trkurl=" +encodeURIComponent(window.location.href);                  
    ajaxTrackerCall.open("GET", ajaxTrackerUrl, true);
    ajaxTrackerCall.send(null);  
}