// ==UserScript==
// @name	TopScroll
// @description	Быстрая прокрутка страницы вверх/вниз.
// @namespace	https://forum.mozilla-russia.org/viewtopic.php?pid=719386#p719386
// @include 	*
// @version	1.0
// ==/UserScript==
topScroll = {
injectDiv: function() {
var body = document.getElementsByTagName("body")[0];
var div = document.createElement("div");
div.id = "topscroll-chrome-extension-bar";
div.setAttribute("style", "position: fixed !important; top: 0 !important; left: 0 !important; bottom: 0 !important; margin: 0 !important; padding: 0 !important; width: 5px !important; height: 100% !important; border-style: none !important; box-shadow: none !important; opacity: 0 !important; z-index: 2147483647 !important;");
div.onclick = topScroll.scrollUp;
div.oncontextmenu = topScroll.scrollDown;
body.appendChild(div);
},
scrollUp: function() {
if (window.pageYOffset === 0) {
topScroll.scrollTo(topScroll.lastScrollPosition);
topScroll.lastScrollPosition = 0;
} else {
topScroll.lastScrollPosition = window.pageYOffset;
topScroll.scrollTo(0);
}
},
scrollDown: function() {
var bottomOffset = document.documentElement.scrollHeight - window.innerHeight;
if (window.pageYOffset === bottomOffset) {
topScroll.scrollTo(topScroll.lastScrollPosition);
topScroll.lastScrollPosition = bottomOffset;
} else {
topScroll.lastScrollPosition = window.pageYOffset;
topScroll.scrollTo(bottomOffset);
}
return false; // Prevent context menu appearing
},
scrollTo: function(endY) {
var duration = 150;
var startY = window.scrollY;
var distance = Math.max(endY,0) - startY;
var startTime = new Date().getTime();
(function loopScroll() {
setTimeout(function () {
var p = Math.min((new Date().getTime() - startTime) / duration, 1); // Progress 0→1
var y = Math.max(Math.floor(startY + distance*(p < 0.5 ? 2*p*p : p*(4 - p*2)-1)), 0);
window.scrollTo(window.pageXOffset, y);
if (p < 1) {
loopScroll();
}
}, 1)
})();
}
};
topScroll.injectDiv();