/**
 * Odesila AJAXovy pozadavek na uri.
 */
function sendAjaxRequest(uri, onReadyStateChangeFunctionBody)
{
	var request = createXmlHttpRequest();

	request.onreadystatechange = function() {
		if (request.readyState == 4) {
			onReadyStateChangeFunctionBody(request);
		}
	};

	request.open("GET", uri, true);
	request.send(null);
}

/**
 * Vytvari XMLHttpRequest.
 * @return XMLHttpRequest 
 * @throws pokud pozadavek nelze vytvorit (napr. chybi podpora v prohlizeci) 
 */
function createXmlHttpRequest()
{
	var request;

	try	{
		// Opera 8.0+, Firefox, Safari
		request = new XMLHttpRequest();
	} catch (e)	{
		// Internet Explorer Browsers
		try	{
			request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e)	{
			// may throw an exception
			request = new ActiveXObject("Microsoft.XMLHTTP");
		}
	}

	return request;
}