how to fix the scrollbar always at the bottom of a div?

Question

I am doing a simple chat application,I want to fix the scrollbar of a div always at the bottom.just like this

Answer 1

function loadchatval(){
    $.post('loadchat.php',function(data){               
    $('#load_chat').html(data); 
    $("#load_chat").animate({ scrollTop: $(document).height() }, "slow");
    return false;
});
}