[devote]

<div style="border: 1px solid #000; height: 300px"></div>
<script>
    window.onscroll = function() {
        if (document.body.scrollHeight - window.innerHeight <= document.body.scrollTop) {
            var el = document.createElement('div');
            el.style.cssText = "border: 1px solid #000; height: 300px";
            el.style.backgroundColor = ["red","green","blue"][Math.floor( Math.random() * 3 )];
            document.body.appendChild( el );
        }
    }
</script>