How to check if jQM popup fits user's viewport? - jquery-mobile

Question

So I've managed to add scrollbars to large jQM popups with css('overflow-y', 'scroll'). But how to do this only when the popup is larger than the user's viewport?
I'm trying with the jquery-visible plugin but I can't get it to respond:
http://jsfiddle.net/mmRnq/124/
$('#test-button').on('click', function(e) {
$('#confirmDialog').popup('open');
// https://stackoverflow.com/questions/20791374/jquery-check-if-element-is-visible-in-viewport
if(!$('#confirmDialog').visible(true)) {
alert('Popup not fully visible - add overflow scrolling');
$('#confirmDialog').css('overflow-y', 'scroll');
}
});

Answer 1

You can use
overflow-y: auto
This makes the scrollbar only visible when it is needed.
Updated FIDDLE
UPDATE:
You can also just make the content of the popup scrollable so the titlebar remains in view:
#confirmDialog .ui-content {
overflow-y: auto;
}
$('#confirmDialog').on({
popupbeforeposition: function() {
var maxHeight = $(window).height() - 120;
$('#confirmDialog .ui-content').height(maxHeight);
}
});
DEMO

Answer 2

I had a popup too large, although it was because of a searchable list. As I wanted to keep the search field at the top whilst scrolling the list only, I had to do this:
$("#confirmDialog").on({
popupbeforeposition: function (e, ui) {
var maxHeight = $(window).height() - 100 + "px";
$("#confirmDialog .ui-content").css("max-height", maxHeight);
},
popupafteropen: function (e, ui) {
var maxHeight = $(window).height() - 150 + "px";
$("#confirmDialog .ui-content ul").css("max-height", maxHeight).css("overflow-y", "scroll");
}
});
Remember do not perform arithmetic on maxHeight once assigned as it's a string, so this doesn't work:
$("#confirmDialog .ui-content").css("max-height", maxHeight - 50);