load jQuery in WordPress only when comments are inside the viewport

jquery_in_viewport.php

<?php 
add_action ( 'wp_head', 'add_jquery_when_comments_in_viewport', 11 );
function add_jquery_when_comments_in_viewport()
{
	?>
	<script type="text/javascript">
	/* <![CDATA[ */
		function jquery_for_comments_onLoad() {
			var element = document.getElementById( "comments" ),
			  current = document.body.clientHeight+document.body.scrollTop,
			  target = element.offsetTop;

			if ( current >= target )  {
				$.defer( "jquery-1.8.1.min.js", {
					bare: true 
				} ).done( console.log( "jquery-1.1.1.min.js loaded" ) );
				window.onscroll = null;
			}
		}
		window.onscroll = jquery_for_comments_onLoad;
	/* ]]> */
	</script>
	<?php 
}