E' definita nello stesso file in questa maniera:
codice:function CreateXmlHttpReq2(handler) { var xmlhttp = null; try { xmlhttp = new XMLHttpRequest(); } catch(e) { try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); } catch(e) { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } } xmlhttp.onreadystatechange = handler; return xmlhttp; }