Fast and lightweight scrolltop button
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// ==UserScript==
// @name Scroll Top Button
// @description Fast and lightweight scrolltop button
// @author NeoCortex
// @license MIT
// @version 0.1.1
// @include *://*
// @namespace https://greasyfork.org/users/12790
// ==/UserScript==
(function (window, undefined) {
var w;
if (typeof unsafeWindow !== undefined) {
w = unsafeWindow;
} else {
w = window;
}
if (w.self != w.top) {
return;
}
var buttonMargins = '15px';
var buttonEdges = '4px';
var buttonSize = '40px';
var buttonOpacity = '0.3';
var buttonHoverOpacity = '0.7';
var fontSize = '35px';
var buttonColor = 'black';
var transitionDelay = '.3s';
var transitionType = 'ease-in-out';
var btnClass = Math.random().toString(36).replace(/[^a-z]+/g, '');
var styles = '.' + btnClass + '{';
styles += 'position: fixed;';
styles += 'cursor: pointer;';
styles += 'bottom: ' + buttonMargins + ';';
styles += 'right: ' + buttonMargins + ';';
styles += 'border-radius: ' + buttonEdges + ';';
styles += 'width: ' + buttonSize + ';';
styles += 'height: ' + buttonSize + ';';
styles += 'opacity: ' + buttonOpacity + ';';
styles +='z-index: 99;';
styles += 'transition: all ' + transitionDelay + ' ' + transitionType + ';';
styles += 'background: ' + buttonColor + ';}';
styles += '.' + btnClass + ':hover{';
styles += 'opacity: ' + buttonHoverOpacity + ';';
styles += 'transform:scale(1.1);}';
styles += '.' + btnClass + '>span{';
styles += 'color: white;opacity: 1;font-size:' + fontSize + ';';
styles += 'width:100%;height:100%;margin:0 auto;display:block;';
styles += 'line-height:' + buttonSize + ';text-align:center;}';
styles += '.' + btnClass + '.' + btnClass + '_hidden{';
styles += 'opacity: 0;transition: all ' + transitionDelay +' ' + transitionType + '}';
var btn = document.createElement('div');
var style = document.createElement('style');
style.innerHTML = styles;
document.body.appendChild(style);
btn.className = btnClass + (w.scrollY === 0 ? ' ' + btnClass + '_hidden' : '');
btn.innerHTML = '<span>🡹</span>';
btn.addEventListener('click', function scrollToTop() {
var scrollDuration = 700;
const scrollHeight = w.scrollY,
scrollStep = Math.PI / ( scrollDuration / 15 ),
cosParameter = scrollHeight / 2;
var scrollCount = 0,
scrollMargin,
scrollInterval = setInterval( function() {
if ( w.scrollY !== 0 ) {
scrollCount = scrollCount + 1;
scrollMargin = cosParameter - cosParameter * Math.cos( scrollCount * scrollStep );
w.scrollTo( 0, ( scrollHeight - scrollMargin ) );
}
else clearInterval(scrollInterval);
}, 15 );
}, false);
document.addEventListener('scroll', function (event) {
var btn = document.querySelector('.' + btnClass);
if(w.scrollY === 0) {
btn.className = btnClass + ' ' + btnClass + '_hidden';
setTimeout(function(){
btn.style.right = '-9999px';
}, 300);
} else {
btn.style.right = buttonMargins;
btn.className = btnClass;
}
});
w.onload = function() {
document.body.appendChild(btn);
};
})(window);