How can I make a div stick to the top of the screen once it's been scrolled to?

Question

I would like to create a div, that is situated beneath a block of content but that once the page has been scrolled enough to contact its top boundary, becomes fixed in place

Answer 1

You've seen this example on Google Code's issue page and (only recently) on Stack Overflow's edit page.

CMS's answer doesn't revert the positioning when you scroll back up. Here's the shamelessly stolen code from Stack Overflow:

function moveScroller() {
    var $anchor = $("#scroller-anchor");
    var $scroller = $('#scroller');

    var move = function() {
        var st = $(window).scrollTop();
        var ot = $anchor.offset().top;
        if(st > ot) {
            $scroller.css({
                position: "fixed",
                top: "0px"
            });
        } else {
            $scroller.css({
                position: "relative",
                top: ""
            });
        }
    };
    $(window).scroll(move);
    move();
}

 
  
 
  
 
    Scroller Scroller Scroller
  


 

And a simple live demo.

A nascent, script-free alternative is position: sticky, which is supported in Chrome, Firefox, and Safari. See the article on HTML5Rocks and demo, and Mozilla docs.