function nuevoAjax(){ 

   abrir_carga()  

	var xmlhttp=false; 

        

		try { 

             

			xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); 

            

			} catch (e) { 

            

			try { 

                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); 

            

			} catch (E) { 

              

			   xmlhttp = false; 

           } 

		   

        } 



         if (!xmlhttp && typeof XMLHttpRequest!='undefined') { 

			  xmlhttp = new XMLHttpRequest(); 

		 } 

		 

        return xmlhttp; 

         

} 



function petision(pag, enDiv, metodo, parametros){
	var ajax = new nuevoAjax();
	ajax.open(metodo, pag + "?nocahe=" + Math.random(), true);
	ajax.onreadystatechange = function() {
		if (ajax.readyState == 4){
			if (ajax.status == 200){ 
					xmlDoc = ajax.responseText;
					document.getElementById(enDiv).innerHTML = xmlDoc;
					cerrar_carga();
			}else{
				return;
			}
		}else{
			return;
		}
	}
	ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
	ajax.send(parametros);
}