Getting a sticky header to “push up”, like in Instagram's iPhone app using CSS and jQuery

Question

The Instagram app has a nice sticky header that pushes the current one up in place of the new one. I found a great tutorial on how to do this natively for Android, but I\'m

Answer 1

First off, thanks to @Chris Spittles for his excellent answer.

I've created a modified version that removes the need to wrap each sticky element, as it simply changes their relative position instead of using fixed positioning.

var stickyHeaders = (function() {

    var $stickies;

    var load = function(stickies, target) {

        if (typeof stickies === "object" && stickies instanceof jQuery && stickies.length > 0) {

            $stickies = stickies.each(function() {

                var $thisSticky = $(this);

                $thisSticky
                    .data('originalPosition', $thisSticky.offset().top)
                    .data('originalHeight', $thisSticky.outerHeight());               
            });

            target.off("scroll.stickies").on("scroll.stickies", function(event) {
                 _whenScrolling(event);     
            });
        }
    };

    var _whenScrolling = function(event) {

        var $scrollTop = $(event.currentTarget).scrollTop();

        $stickies.each(function(i) {            

            var $thisSticky = $(this),
                $stickyPosition = $thisSticky.data('originalPosition'),
                $newPosition,
                $nextSticky;

            if ($stickyPosition <= $scrollTop) {

                $newPosition = Math.max(0, $scrollTop - $stickyPosition);
                $nextSticky = $stickies.eq(i + 1);

                if($nextSticky.length > 0) {

                    $newPosition = Math.min($newPosition, ($nextSticky.data('originalPosition') -  $stickyPosition) - $thisSticky.data('originalHeight'));
                }

            } else {

                $newPosition = 0;
            }

            $thisSticky.css('transform', 'translateY(' + $newPosition + 'px)');

            //could just as easily use top instead of transform
            //$thisSticky.css('top', $newPosition + 'px');
        });
    };

    return {
        load: load
    };
})();

$(function() {
    stickyHeaders.load($(".followMeBar"), $(window));
});

The css is simplified to:

.followMeBar {
    background: #999;
    padding: 10px 20px;
    position: relative;
    z-index: 1;
    color: #fff;
}

/* For aesthetics only */

body {
    margin: 0;
    font-family: Segoe, "Segoe UI", "DejaVu Sans", "Trebuchet MS", Verdana, sans-serif;
}

http://plnkr.co/edit/wk3h40LfBdN1UFtDLZgY?p=preview

And here's another example showing how you can have an offset when using a fixed header:

http://plnkr.co/edit/8YBqdCIKruVKYRXbZnCp?p=preview