div跟随javasript

function showdiv() ...{

var x = window.event.x;
var y = window.event.y;
var show = document.getElementById("ShowInfo");
show.style.visibility = "visible";
show.style.top = y;
show.style.left = x;
show.style.background="#ffff00";
show.innerHTML = "1234567";
document.onmousemove = moveToMouseLoc;
}

function Remove()
...{
        var show=document.getElementById("ShowInfo");
        if(show != "" || show != null)
        ...{
            show.style.visibility = "hidden";
        }    
}
function moveToMouseLoc(e)
...{
    x = window.event.x;
    y = window.event.y;
  var show = document.getElementById("ShowInfo");
  show.style.left = x;
  show.style.top = y;
  return true;
}