// ==UserScript==
// @name        Scroll To Top
// @description Scroll To Top.
// @namespace   2k1dmg@userscript
// @license     GPL version 3 or any later version; http://www.gnu.org/licenses/gpl.html
// @include     *
// @version     1
// @author      2k1dmg
// @grant       none
// @noframes
// ==/UserScript==
(function() {
'use strict';
var sttClassName = 'coTcfkMc_scrollToTop';
var timeoutID;
function scrollToTop() {
var scrolled = window.pageYOffset || document.documentElement.scrollTop;
var ch = document.documentElement.clientHeight;
if(scrolled === 0) {
clearTimeout(timeoutID);
timeoutID = null;
return;
}
else if(scrolled < ch) {
window.scrollTo(0,parseInt(scrolled/1.3));
}
else if(scrolled < ch * 3) {
window.scrollTo(0,parseInt(scrolled/1.5));
}
else {
window.scrollTo(0,parseInt(scrolled/2));
}
timeoutID = setTimeout(scrollToTop, 15);
}
function onClick(event) {
if(typeof timeoutID == 'number')
return;
scrollToTop();
}
function toggleScrollToTop() {
var scrolled = window.pageYOffset || document.documentElement.scrollTop;
var ch = document.documentElement.clientHeight;
var elm = document.querySelector('.'+sttClassName);
if(scrolled > ch/1.1) {
elm.style.cssText = 'display: block;';
}
else {
elm.style.cssText = 'display: none;';
}
}
window.onscroll = toggleScrollToTop;
window.onwheel = function() {
if(typeof timeoutID != 'number')
return;
clearTimeout(timeoutID);
timeoutID = null;
};
function addCSSStyle() {
var cssStyle = document.createElement('style');
cssStyle.type = 'text/css';
cssStyle.textContent = [
'.'+sttClassName+' {',
'	width: 40px;',
'	height: 40px;',
'	line-height: 30px;',
'	text-align: center;',
'	background: whiteSmoke;',
'	font-weight: bold;',
'	font-size: 25px;',
'	color: #444;',
'	text-decoration: none;',
'	position: fixed;',
'	bottom: 0;',
'	right: 0;',
'	display: none;',
'	border: 1px solid grey;',
'	border-top-left-radius: 8px;',
'	box-shadow: 0 0 3px grey;',
'	transition: opacity 250ms ease-out;',
'	opacity: .1;',
'	z-index: 1000;',
'	cursor: pointer;',
'}',
'.'+sttClassName+':hover {',
'	text-decoration: none;',
'	opacity: 1;',
'}'
].join('\n');
if(document.head)
document.head.appendChild(cssStyle);
}
addCSSStyle();
var div = document.createElement('div');
div.className = sttClassName;
div.textContent = '↑';
div.onclick = onClick;
document.body.appendChild(div);
toggleScrollToTop();
})();