jQuery alert after 100 pixels scrolled
<p>Is it possible to fire an alert after a user scrolls 100 pixels. </p>

<p>Here's what I have so far but I know I'm missing something;</p>

<pre><code>$(window).scroll(function() {
    if (document.documentElement.clientHeight + 
        $(document).scrollTop() == "100px")
    { 
        alert("You've scrolled 100 pixels.");
    }
});
</code></pre>
