Created
November 11, 2019 15:28
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'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 ); |
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scrollovátko na částech webů, prezentuje bloky na obrozovku bez scrollování