双击鼠标滚动屏幕的代码[JavaScript]

//双击鼠标滚动屏幕的代码
var currentpos,timer;
function initialize()
{
timer=setInterval ("scrollwindow ()",30);
}
function sc()
{
clearInterval(timer);
}
function scrollwindow()
{
currentpos=document.body.scrollTop;
window.scroll(0,++currentpos);
if (currentpos !=document.body.scrollTop)
sc();
}
document.onmousedown=sc
document.ondblclick=initialize