https://laraza.com/wp-content/themes/contenthub/resources/scripts/libs/verticalscrolling.js

1(function(){
2	var scrollY = window.scrollY || window.pageYOffset || document.documentElement.scrollTop;
3	var scrollTargetY =  0;
4	var currentTime = 0;
5	var time = null;
6	var p = null;
7	var t = null;
8	var easing = 'easeOutSine';
9
10	// Ecuaciones easing de https://github.com/danro/easing-js/blob/master/easing.js.
11	var easingEquations = {
12		easeOutSine: function( pos ){
13			return Math.sin( pos * ( Math.PI / 2 ) );
14		},
15		easeInOutSine: function( pos ){
16			return ( -0.5 * ( Math.cos ( Math.PI * pos ) - 1 ) );
17		},
18		easeInOutQuint: function( pos ){
19			if( ( pos /= 0.5 ) < 1 ){
20				return 0.5 * Math.pow( pos, 5 );
21			}
22			return 0.5 * ( Math.pow( ( pos - 2 ), 5 ) + 2 );
23		}
24	};
25
26	/**
27	 * Smooth Vertical Scrolling.
28	 *
29	 * @param {string} scrollTargetY - Número > 0 de "pixeles" del scroll vertical de un target. Ej: el.offsetTop.
30	 * @param {object} speed - tiempo en pixeles por segundo.
31	*/
32	function scrollToY( scrollTargetY, speed ) {
33
34		scrollTargetY = scrollTargetY || 0;
35		speed         = speed || 2000;
36
37		// Reseteamos variables para los próximos click del usuario.
38		p = 0;
39		currentTime = 0;
40
41		// Min time .1, Max time .8 segundos.
42		time = Math.max( .1, Math.min( Math.abs( scrollY - scrollTargetY ) / speed, .8 ) );
43
44		// Ejecutamos una vez para comenzar
45		tick();
46	}
47
48	// Add loop de animación.
49	function tick() {
50
51		currentTime += 1 / 60;
52
53		p = currentTime / time;
54		t = easingEquations[ easing ]( p );
55
56		if ( p < 1 ) {
57			requestAnimationFrame( tick );
58
59			window.scrollTo( 0, scrollY + ( ( scrollTargetY - scrollY ) * t ) );
60		} else {
61			// Finalización del scroll.
62			window.scrollTo( 0, scrollTargetY );
63		}
64	}
65
66	window.scrollToY = scrollToY;
67})();