Affix js with vanilla js

affix.html

<script type="text/javascript">
	window.onscroll = scroll;
	function scroll () {
		var scrollTop = window.pageYOffset;
		console.log(scrollTop);
		if( scrollTop > 363 ){
			document.getElementById('summary').style.top="20px";
			document.getElementById('summary').style.position="fixed";
		}
		else
		{
			document.getElementById('summary').style.position="relative";
			document.getElementById('summary').style.top="50px";
		}
	}

</script>