function getXMLHTTPReques(){
	try{
		req = new XMLHttpRequest();
	}catch(err1){
		
		try{
			req = new ActiveXObject("Msxm12.XMLHTTP");
		}catch(err2){
		
			try{
				req = new ActiveXObject("Microsoft.XMLHTTP");
			}catch(err3){
				req = false ;
			}
		}
	}
	return req;
}

function upAjax(idSitio, idDiv,opcion){
	var req = getXMLHTTPReques() ;
	if(req){
		
		var div = document.getElementById(idDiv) ;
		var myRand = parseInt(Math.random()*9999999999999) ;
		
		req.onreadystatechange = function(){
			if(req.readyState == 4){
				div.innerHTML = req.responseText ;
			}
			else{
				div.innerHTML = '<img src="images/visite-loading.gif" style="padding-left:10px;padding-right:10px">' ;
			}
		}
		req.open("GET", "miAsincrono.php?opcion="+opcion+"&idsit="+idSitio+"&rand="+myRand, true) ;
		req.send(null) ;
	}
}