<style>
    #back-to-top {
	        position: absolute;
	left: 20px; // adjust this dynamically w/jQuery so that it is on the right!
	left: 20px;
    top: 120px;
	        width: 150px;
	        height: 25px;
	        background-color: gray;
    }
</style>
<script>
    var child = AJS.$jQuery('<div/>', {
	        'id': 'back-to-top'
    });
    child.html('<a href="#">Back to top</aa>');
    child.on('click', function () {AJS.$jQuery(window).scrollTop();});
 
AJS.$
    jQuery('#page').append(child);
</script>