[danik.js]

<style>
    html, body, div{height: 100%;margin:0;padding:0}
    div{float:right;width:80%;overflow: auto;}
    span{display:block;height:2000px;}
</style>
<script>
    function scrollToBottom() {
        scroller.scrollTop = scroller.scrollHeight - scroller.offsetHeight;
    }
</script>

<div id=scroller>
    <span></span>
</div>

<button onclick=scrollToBottom()>Прокрутить вниз</button>