scroll.js

		'use strict';
		const MIN_SCROLL_TIME = 250; // in ms
		const JS_WORKING_ONLY_CLASSNAME = 'js';
		const UP_ARROW_CODE = 38;
		const DOWN_ARROW_CODE = 40;
		const slideIds = [];

		[ ...document.getElementsByTagName( 'main' )[ 0 ].children ].forEach( ( /** @type {HTMLElement} */ item ) => {
			item.classList.add( JS_WORKING_ONLY_CLASSNAME );
			slideIds.push( item.id );
		} );
		const footer = document.querySelector( 'body>footer' );
		footer.hidden = true;

		document.addEventListener( 'touchstart', handleTouchStart, false );
		document.addEventListener( 'touchmove', handleTouchMove, false );
		document.addEventListener( 'touchend', handleTouchEnd, false );
		document.addEventListener( 'touchcancel', handleTouchEnd, false );
		var xDown = null;
		var yDown = null;
		var doTouchBreak = null;
		var minDelta = 100;
		function handleTouchEnd() {
			doTouchBreak = null;
		};
		function handleTouchStart( evt ) {
			xDown = evt.touches[ 0 ].clientX;
			yDown = evt.touches[ 0 ].clientY;
		};
		function handleTouchMove( evt ) {
			if ( !xDown || !yDown || doTouchBreak ) { return; }
			var xUp = evt.touches[ 0 ].clientX;
			var yUp = evt.touches[ 0 ].clientY;
			var xDiff = xDown - xUp;
			var yDiff = yDown - yUp;
			if ( Math.abs( yDiff ) > Math.abs( xDiff ) )
			{
				if ( yDiff > minDelta )
				{
					slide( +1 );
					doTouchBreak = true;
				} else if ( yDiff < -minDelta )
				{
					slide( -1 );
					doTouchBreak = true;
				}
			}
			if ( doTouchBreak )
			{
				xDown = null;
				yDown = null;
			}
		};

		const slide = ( /** @type {Number} */ direction ) => {
			const currentPosition = slideIds.indexOf( window.location.hash.substr( 1 ) );
			let newPosition = currentPosition + direction;
			if ( newPosition < slideIds.length )
			{
				if ( direction === -1 && newPosition === slideIds.length - 2 && !footer.hidden )
				{
					footer.hidden = true;
				} else if ( newPosition >= 0 )
				{
					window.location.hash = slideIds[ newPosition ];
				}
			} else
			{
				footer.hidden = false;
				window.scrollTo( {
					left: 0,
					top: document.body.scrollHeight,
					behavior: 'smooth'
				} );
			}
			return true;
		};

		document.addEventListener( 'keydown', ( /** @type {KeyboardEvent} */ event ) => {
			if ( event.keyCode === UP_ARROW_CODE )
			{
				slide( -1 );
			} else if ( event.keyCode === DOWN_ARROW_CODE )
			{
				event.preventDefault();
				slide( +1 );
			}
		}, false );

		document.addEventListener( 'wheel', ( /** @type {WheelEvent} */ event ) => {
			if ( !this.prevTimeStamp )
			{
				this.prevTimeStamp = 0;
			}
			if ( ( event.timeStamp - this.prevTimeStamp ) > MIN_SCROLL_TIME )
			{
				slide( ( event.deltaY < 0 ) ? -1 : +1 );
			}
			this.prevTimeStamp = event.timeStamp;
		}, false );

asi pokročilá verze tohoto: https://gist.github.com/iiic/21e7d019051545756de5bb2e98b2f2f0