var xmlhttp;

function loadXMLDoc(url, callback) {
	xmlhttp = null;
	// code for Mozilla, etc.
	if (window.XMLHttpRequest) {
		xmlhttp = new XMLHttpRequest();
	}
	// code for IE
	else if (window.ActiveXObject) {
		xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
	}
	if (xmlhttp != null) {
		xmlhttp.onreadystatechange = callback;
		xmlhttp.open("GET", url, true);
		xmlhttp.send(null);
	} else {
 		alert("Your browser does not support XMLHTTP.")
  }
}