JS代码首次打开,,缺少对象
第一次打开网页
下面中的代码
var d = document;
总是提示缺少对象,,是怎么回事

var startX =3,
startY = 250;
var ns = (navigator.appName.indexOf( "Netscape ") != -1);
var d = document;
function ml(id)
{
var el=d.getElementById?d.getElementById(id):d.all?d.all[id]:d.layers[id];
if(d.layers)el.style=el;
el.sP=function(x,y){this.style.left=x;this.style.top=y;};
el.x = startX;
if (verticalpos== "fromtop ")
el.y = startY;
else{
el.y = ns ? pageYOffset + innerHeight : document.body.scrollTop + document.body.clientHeight;
el.y -= startY;
}
return el;
}

------解决方案--------------------
<script language=javascript defer>
//后面加defer
------解决方案--------------------
var d;
function ml(id)
{
d = document;