function getXhr(){
	var xmlHttp;
	try { xmlHttp = new XMLHttpRequest(); } catch (e) {
		try { xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {
			try { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {
				return null;
			}
		}
	}
    return xmlHttp;
}