[jquery] jquery how to get the page's current screen top position?

jquery how to get the page's current screen top position?

If I scroll my mouse wheel to some part of the page, how do I get the page's current top position?

I want click one element in my page, then open a div which top is to current screen top.

So just put the current screen top position to:

$('#content').css('top','current position');

And

#content
{
position:absolute;
left:100px;
}

Use this to get the page scroll position.

var screenTop = $(document).scrollTop();

$('#content').css('top', screenTop);