document.onkeyup = function(event){
        event = event || window.event;
        for(var i=0;i<as.length;i++){
            as[i].style.background = 'none';
        }
        if(event.keyCode == 38){
         if(index<=0){
                index = as.length;
            }
         index--;
         as[index].style.background = '#ccc';
        }else if(event.keyCode == 40){
         index++;
         if(index>=as.length){
                index = 0;
            }
         as[index].style.background = '#ccc';
        }else if(event.keyCode == 13 && index!=-1){
            title.innerHTML = as[index].innerHTML;
            menu.style.display = 'none';
            index = -1;
        }
    }