up button

up-btn.php

	<button id="up-btn">Наверх</button>

	<script>
	       var btnUp = document.getElementById('up-btn');
	       window.onscroll = function() {
	           var offset = window.pageYOffset;
	           if(offset > window.innerHeight) {
	               btnUp.style.display = 'inline';
	           }
	           else {
	               btnUp.style.display = 'none';
	           }
	       }
	       btnUp.onclick = function() {
	           jQuery('html').animate({scrollTop:0},100);
	       }
	</script>