js 鼠标双击滚动单击停止

var currentpos,timer;
function initialize()
{
    timer=setInterval("scrollwindow()",3);
}
function sc(){
    clearInterval(timer);
}
function scrollwindow(){
    if(document.body.scrollTop){//加了DTD头时,document.body.scrollTop值始终为0,在此判断一下
        currentpos=document.body.scrollTop;
        window.scroll(0,++currentpos);
            if (currentpos != document.body.scrollTop){
                sc();
            }
    }
    else{
        currentpos=document.documentElement.scrollTop;
            window.scroll(0,++currentpos);
            if (currentpos != document.documentElement.scrollTop){
                sc();
            }
    }
}

document.onmousedown=sc
document.ondblclick=initialize