js实现浮动框跟随页面滚动，最后停留在原来位置

<div style="background:red; width:1000px; height:7000px; margin:auto;">  </div>
<div id="aa" style="position: absolute;right: 0px; top: 4600px;"><img src="001.jpg"/></div>
<script>
function scrollx(p){
var d = document,dd = d.documentElement,db = d.body,w = window,o = d.getElementById(p.id),ie6 = /msie 6/i.test(navigator.userAgent),style,timer;
if(o){
o.style.cssText +=";position:"+(p.f&&!ie6?'fixed':'absolute')+";"+(p.l==undefined?'left:0;':'left:'+p.l+'px;')+(p.t!=undefined?'top:'+p.t+'px':'bottom:0');
if(p.f&&ie6){
o.style.cssText +=';left:expression(documentElement.scrollLeft + '+(p.l==undefined?dd.clientWidth-o.offsetWidth:p.l)+' + "px");top:expression(documentElement.scrollTop +'+(p.t==undefined?dd.clientHeight-o.offsetHeight:p.t)+'+ "px" );';
dd.style.cssText +=';background-image: url(about:blank);background-attachment:fixed;';
}else{
if(!p.f){
w.onresize = w.onscroll = function(){
clearInterval(timer);
timer = setInterval(function(){
//双选择为了修复chrome 下xhtml解析时dd.scrollTop为 0
var st = (dd.scrollTop||db.scrollTop),c;
c = st  - o.offsetTop + (p.t!=undefined?p.t:(w.innerHeight||dd.clientHeight)-o.offsetHeight);
if(c!=0){
o.style.top = o.offsetTop + Math.ceil(Math.abs(c)/10)*(c<0?-1:1) + 'px';
}else{
clearInterval(timer);
}
},10)

}

}
}
}
}
scrollx({
id:'aa',
t:300,
})

/*
id 你要滚动的内容的id
l 横坐标的位置  不写为紧贴右边
t 你要放在页面的那个位置默认是贴着底边 0是贴着顶边
f 1表示固定 不写或者0表示滚动
*/
</script>