Get height of non-overflowed portion of div

Question

Say I have a wrapper div with a overflow:hidden on it and a div inside that that spans far below the visible portion. How can I get the visible height of the in

Answer 1

As basic algorithm this could work:

var offset = 0;
var node = document.getElementById("inner");
while (node.offsetParent && node.offsetParent.id != "wrapper")
{
    offset += node.offsetTop;
    node = node.offsetParent;
}
var visible = node.offsetHeight - offset;

But if you're doing these kinds of things, maybe you already use jQuery, which might be of service with its .height() and .offset() functions:

$("#wrapper").height()-
$("#inner").offset()['top']+
$("#wrapper").offset()['top'];