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
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// ==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     2015.8.17
// @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://greasyfork.org/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'){ //当前值
                    objAttr = Math.round(parseFloat( getStyle(obj,attr) ) * 100);
                }else if( attr=="scrollTop" ){
                    objAttr = parseInt( getSize("scrollTop") );
                }
                else{
                    objAttr = parseInt( getStyle(obj,attr) );
                }
                // 2.计算运动速度
                var jsonattr = parseFloat( json[attr] );//目标值
                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 if(attr == "scrollTop"){
                    document.documentElement.scrollTop=document.body.scrollTop = objAttr+iSpeed;
                }
                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}#scrollMars-troy #mars-point{width:100px;height:100px;position:absolute;top:0;left:-40px}#scrollMars-troy div div.sroll-btn-troy{width:50px;height:50px;text-align:center;background:#303030;color:#fff;display:block;opacity:0.8;filter: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.sroll-btn-troy:hover{background:#FF0000}';
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);