var peticion = false; 
try{ 
   // Mozilla/Safari 
   if (window.XMLHttpRequest) 
           peticion = new XMLHttpRequest(); 
   // IE 
   else if (window.ActiveXObject) 
           peticion = new ActiveXObject("Microsoft.XMLHTTP"); 
} 
  
        catch (e) { 
                alert(e); 
        } 
// Error  
if(!peticion) 
        alert("no se pudo crear");

function ObtDatos(url) { 
     if(peticion) { 
          peticion.open("GET", url); 
          peticion.onreadystatechange = function(){ 
               if (peticion.readyState == 4 ) {
                    var DivDestino = document.getElementById("DivDestino");
                    if(peticion.responseText == "NO"){ 
                    DivDestino.innerHTML = "<div id='error'><font size='1' face='Arial' color='#FF0000'>&nbsp;No disponible</font></div>";
                    
                    }else if (peticion.responseText == "SI") {
                    DivDestino.innerHTML = "<div id='error'><font size='1' face='Arial' color='#000080'>&nbsp;Disponible</font></div>";
                    
                    }else if (peticion.responseText == "VACIO") {
                    DivDestino.innerHTML = "<div id='error'><font size='1' face='Arial' color='#FF0000'>&nbsp;Login Inválido</font></div>";
                    }
               } 
          } 
peticion.send(null); 
     } 
} 
  
function Comprobar() { 
          var DivDestino = document.getElementById("DivDestino"); 
          DivDestino.innerHTML = "<div></div>"; 
               ObtDatos("/registro/soporte/login.asp?q=" + document.registro.login.value +"&date="+Date()); 
}