https://jonathenzc.github.io/js/ToTop.js

1(function($) { 
2	// When to show the scroll link
3	// higher number = scroll link appears further down the page   
4	var upperLimit = 1000;
5	
6	// Our scroll link element
7	var scrollElem = $('#totop');
8   
9	// Scroll to top speed
10	var scrollSpeed = 500;
11   
12	// Show and hide the scroll to top link based on scroll position   
13	scrollElem.hide();
14	$(window).scroll(function () {            
15		var scrollTop = $(document).scrollTop();       
16		if ( scrollTop > upperLimit ) {
17			$(scrollElem).stop().fadeTo(300, 1); // fade back in           
18		}else{       
19			$(scrollElem).stop().fadeTo(300, 0); // fade out
20		}
21	});
22	// Scroll to top animation on click
23	$(scrollElem).click(function(){
24		$('html, body').animate({scrollTop:0}, scrollSpeed); return false;
25	});
26})(jQuery);