Lite Add button for Smooth Scroll to the top / bottom

为页面添加按钮，平滑的滚动到顶部/底部
Versión del día 15/8/2015. Echa un vistazo a la versión más reciente.
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Ajuste de línea
// ==UserScript==
// @name	Lite Add button for Smooth Scroll to the top / bottom
// @author	burningall
// @description	为页面添加按钮，平滑的滚动到顶部/底部
// @version     2015.8.15
// @include		*
// @grant       GM_addStyle
// @run-at		document-start
// @compatible  chrome  完美支持
// @compatible  firefox  完美支持
// @license     The MIT License (MIT); http://opensource.org/licenses/MIT
// @supportURL		http://www.burningall.com
// @contributionURL	[email protected]|alipay.com
// @namespace https://greatest.deepsurf.us/zh-CN/users/3400-axetroy
// ==/UserScript==
// 
// 
// 
//=======快捷键======
//alt+1>>>>>>回到顶部
//alt+2>>>>>>去到底部
//================公共函数区============
(function(window,document){

function addEvent(obj, type, fn){
	return obj.addEventListener ?
			obj.addEventListener(type, function(e){
				var ev = window.event ? window.event : (e ? e : null);
				ev.target = ev.target || ev.srcElement;
				if( fn.call(obj,ev)===false ){//回掉函数为false，则阻止默认时间
					e.cancelBubble = true;//阻止冒泡
					e.preventDefault();//chrome，firefox下阻止默认事件
				}
			}, false)
			 :
			obj.attachEvent('on' + type, function(e){
				//fn.call(obj,e);//解决IE8下，this是window的问题
				var ev = window.event ? window.event : (e ? e : null);
				ev.target = ev.target || ev.srcElement;
				if(fn.call(obj,ev)===false ){
					e.cancelBubble = true;//阻止冒泡
					return false;//阻止默认事件，针对IE8
				}
			});
}

function getSize(obj) {
	return document.documentElement[obj] !== 0 ? document.documentElement[obj] : document.body[obj];
}

function hasScroll() {
	return getSize('scrollHeight') > getSize('clientHeight') ? true : false;
}

function getStyle(obj, attr) {
	return obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj)[attr];
}

function $(id) {
	return document.getElementById(id);
}

function animate(obj,json,cfgjson){
		clearInterval(obj.animate);
		obj.animate = setInterval(function() {
			var bStop = true;//判断运动是否停止
			for(var attr in json){//attr代表属性,'width','height'.而json[attr]代表数值
				// 1. 取得当前的值（可以是width，height，opacity等的值）
				var objAttr = 0 ;
				if(attr == 'opacity'){//获取当前数值
					objAttr = Math.round(parseFloat( getStyle(obj,attr) ) * 100);
				}else{
					objAttr = parseInt( getStyle(obj,attr) );
				}
				// 2.计算运动速度
				var jsonattr = parseFloat( json[attr] );
				var speedConfig = (cfgjson && typeof ( cfgjson.speed ) != 'undefined') ? cfgjson.speed : 10;
				var iSpeed = (jsonattr - objAttr) / speedConfig;	//(目标数值-当前数值)/10
				iSpeed = iSpeed > 0 ? Math.ceil(iSpeed) : Math.floor(iSpeed);	//如果速度>0，则速度向上取整，如果小于0，则保留小数
				// 3. 检测所有运动是否到达目标
				//objAttr,当前点，json[attr]为目标点
				if ( (iSpeed>0 && objAttr <= jsonattr) || (iSpeed<0 && objAttr >= jsonattr) ) {//如果有其中一项没有达到目标
					bStop = false;
				}
				if (attr == "opacity") {
					obj.style.filter = 'alpha(opacity:' + (objAttr + iSpeed) + ')';
					obj.style.opacity = (objAttr + iSpeed) / 100;
				} else {
					obj.style[attr] = objAttr + iSpeed + 'px';	//赋值开始运动
				}
				if (bStop) { // 表示所有运动都到达目标值
					clearInterval(obj.animate);
					if( cfgjson && typeof cfgjson.endFn != 'undefined' ){
						cfgjson.endFn.call(obj);
					}
				}
			}//for
		},20);
}
//================样式区============
var cssText = '\
#scrollMars-troy{\
	position:fixed;\
	right:30px;\
	z-index:9999999;\
}\
\
.sroll-btn-troy{\
	width:50px;\
	height:50px;\
	text-align:center;\
	background:#303030;\
	color:#fff;\
	display:block;\
	opacity:0.8;\
	fitter:alpha(opacity:80);\
	cursor:pointer;\
	border-radius:50%;\
	box-shadow:2px 2px 40px 2px #303030;\
	line-height:50px;\
	font-size:35px;\
	font-style:inherit;\
	font-weight:bold;\
	font-family:"宋体";\
}\
#scrollMars-troy>div>div:hover{\
	background:#FF0000;\
}\
#mars-point{\
	width:100px;\
	height:100px;\
	position:absolute;\
	top:0;\
	left:-40px;\
}\
'
GM_addStyle(cssText);
//================主要代码区============
function scroll(dir) { //obj随意，dir>0往上滚，dir<0往下滚
	var position,speed,scrollTop,scrollHeight,clientHeight;
	clearInterval(document.timerScroll);
	scrollHeight = getSize('scrollHeight');
	clientHeight = getSize('clientHeight');
	document.timerScroll = setInterval(function() {
		scrollTop = getSize('scrollTop');	
		if (dir > 0) { //往上滚动
			speed = ( scrollTop/10 ) + 1;
			position = scrollTop - speed;
			if (position <= 0) { //如果滚到顶部
				document.body.scrollTop = document.documentElement.scrollTop = 0;
				clearInterval(document.timerScroll);
			}
		} else { //往下滚动
			speed = ( (scrollHeight-scrollTop-clientHeight) / 10 ) + 1;
			position = scrollTop + speed;
			if (position + clientHeight >= scrollHeight) { //如果滚到底部
				document.body.scrollTop = document.documentElement.scrollTop = scrollHeight;
				clearInterval(document.timerScroll);
			}
		}
		document.body.scrollTop = document.documentElement.scrollTop = position;
	}, 20);
}

function marsMove(dir){
	var mars = $('scrollMars-troy');
	var point = $('mars-point');
	if(dir=="moveIn"){//移入
		clearTimeout(mars.timerHover); 
		animate(mars,{"right":"30","opacity":"100"});
		animate(point,{"left":"0"});
	}else if(dir=="moveOut"){//移出
		clearTimeout(mars.timerHover);
		mars.timerHover = setTimeout(function(){
			animate(mars,{"right":"-30","opacity":"30"});
			animate(point,{"left":"-40"});
		},3000);
	}
}

function init() {
	var scrollBtn = $("scrollMars-troy");
	if( scrollBtn ){
		scrollBtn.style.top = (getSize('clientHeight') / 3) + 'px';
	}
	if (hasScroll() === true && !scrollBtn) { //如果有滚动条，并且没有按钮
		var mars = document.createElement('div'),goTop,goBtm,point;
		mars.id = "scrollMars-troy";
		window.top.document.documentElement.appendChild(mars);
		mars.innerHTML = "\
		<div id='mars-point'></div>\
		<div>\
			<div id='goTop-troy' title='返回顶部' class='sroll-btn-troy'></div>\
			<div id='goBtm-troy' title='去到底部' class='sroll-btn-troy'></div>\
		</div>\
		";
		goTop = $("goTop-troy");
		goBtm = $("goBtm-troy");
		goTop.innerHTML = "↑";
		goBtm.innerHTML = "↓";
		$('scrollMars-troy').style.top = (getSize('clientHeight') / 3) + 'px';
		addEvent(goTop, "click", function() {
			scroll(1);
			return false;
		});
		addEvent(goBtm, "click", function() {
			scroll(-1);
			return false;
		});
		addEvent(mars,'mouseover',function(){
			marsMove("moveIn");
			return false;
		});
		addEvent(mars,'mouseout',function(){
			marsMove("moveOut");
			return false;
		});
		addEvent(mars,'mousedown',function(){
			return false;
		});
		marsMove("moveOut");
	}
}
//================执行区============
addEvent(window,"mousewheel",function(){
	clearInterval(document.timerScroll);
});
addEvent(window,"DOMMouseScroll",function(){
	clearInterval(document.timerScroll);
});

addEvent(window.top, "resize", function() { //页面大小改变，初始化按钮
	init();
});

addEvent(document, 'DOMContentLoaded', function() {
	init();
});
//================快捷键区============
addEvent(window, 'keydown', function(e) {
	if (e.altKey && e.keyCode == 49) { //alt+1，向上滚动
		scroll(1);
	} else if (e.altKey && e.keyCode == 50) { //alt+2，向下滚动
		scroll(-1);
	} else if (e.ctrlKey && e.altKey) { //ctrl+alt,调出按钮
		marsMove("moveIn");
	} 
});//监听keydown，快捷键

})(window,document);