Detect if div is visible in browser window

I have multiple collapsible divs like so

+--------------+
| Div 1        |
+--------------+
| Div 2        |
+--------------+
| Div 3        |
+--------------+

Now when I click on one of the divs it expands

Question: How do I dete开发者_如何学编程ct that expanded div was expanded over browser window (bottom border)?

---

You could try this, it's an untested idea off the top of my head so some modification may be needed.

var div1Height = $("#div1").height();
var div2Height = $("#div2").height();
var div3Height = $("#div3").height();
var windowSize = $(window).height();


//assign function for on click (you'll want to change this)
$("#div1, #div2, #div3").click(function(e){
if(div1Height > windowSize){
//assuming div1 is at the top
console.log("div 1 passing extents");
}
if((div2Height + parseInt($("#div2").position().top) > windowSize){
console.log("div 2 passing extents");
}
if((div3Height + parseInt($("#div3").position().top) > windowSize){
console.log("div 3passing extents");
}

});