//Gets the browser specific XmlHttpRequest Object
function getXmlHttpRequestObject() {
	if (window.XMLHttpRequest) {
		return new XMLHttpRequest(); //Not IE
	} else if(window.ActiveXObject) {
		return new ActiveXObject("Microsoft.XMLHTTP"); //IE
	} else {
		//Display your error message here. 
		//and inform the user they might want to upgrade
		//their browser.
		return false;
	}
}

function ajax_request(url, callback_function) {
	//Get our browser specific XmlHttpRequest object.
	var receiveReq = getXmlHttpRequestObject();
	
	// If the browser doesn't support Ajax, just give up
	if (receiveReq == false) return false;
	
	//If our XmlHttpRequest object is not in the middle of a request, start the new asyncronous call.
	if (receiveReq.readyState == 4 || receiveReq.readyState == 0) {
		//Setup the connection as a GET call to url
		//True explicity sets the request to asyncronous (default).
		receiveReq.open("GET", url, true);
		//Set the function that will be called when the XmlHttpRequest objects state changes.
		receiveReq.onreadystatechange = callback_function;
		//Make the actual request.
		receiveReq.send(null);
	}			
}

function track_link(id) {
	if (id != 0) {
		ajax_request('/external_link.html?track=1&id=' + id, null);
	}
	return true;
}