scrolltop

<script>
lastScrollY=0;
function heartBeat(){
var diffY;
if (document.documentElement && document.documentElement.scrollTop)
diffY = document.documentElement.scrollTop;
else if (document.body)
diffY = document.body.scrollTop
else
{/*Netscape stuff*/}
percent=.1*(diffY-lastScrollY);
if(percent>0)percent=Math.ceil(percent);
else percent=Math.floor(percent);
document.getElementById("full").style.top=parseInt(document.getElementById("full").style.top)+percent+"px";
lastScrollY=lastScrollY+percent;
}
suspendcode="<div id=\"full\" style='right:15px;POSITION:absolute;TOP:600px;z-index:100; cursor:pointer;'><a onclick='window.scrollTo(0,0);' ><img src='./lib/tpl/vector/totop.gif'></a><br></div>"
document.write(suspendcode);
window.setInterval("heartBeat()",1);
</script>

 

jquery 

 

//** jQuery Scroll to Top Control script- (c) Dynamic Drive DHTML code library: http://www.dynamicdrive.com.
//** Available/ usage terms at http://www.dynamicdrive.com (March 30th, 09')
//** v1.1 (April 7th, 09'):
//** 1) Adds ability to scroll to an absolute position (from top of page) or specific element on the page instead.
//** 2) Fixes scroll animation not working in Opera. 


var scrolltotop={
    //startline: Integer. Number of pixels from top of doc scrollbar is scrolled before showing control
    //scrollto: Keyword (Integer, or "Scroll_to_Element_ID"). How far to scroll document up when control is clicked on (0=top).
    setting: {startline:1, scrollto: 0, scrollduration:1000, fadeduration:[500, 100]},
    controlHTML: '<img src="up.png" style="width:24px; height:24px" />', //HTML for control, which is auto wrapped in DIV w/ ID="topcontrol"
    controlattrs: {offsetx:5, offsety:5}, //offset of control relative to right/ bottom of window corner
    anchorkeyword: '#top', //Enter href value of HTML anchors on the page that should also act as "Scroll Up" links

    state: {isvisible:false, shouldvisible:false},

    scrollup:function(){
        if (!this.cssfixedsupport) //if control is positioned using JavaScript
            this.$control.css({opacity:0}) //hide control immediately after clicking it
        var dest=isNaN(this.setting.scrollto)? this.setting.scrollto : parseInt(this.setting.scrollto)
        if (typeof dest=="string" && jQuery('#'+dest).length==1) //check element set by string exists
            dest=jQuery('#'+dest).offset().top
        else
            dest=0
        this.$body.animate({scrollTop: dest}, this.setting.scrollduration);
    },

    keepfixed:function(){
        var $window=jQuery(window)
        var controlx=$window.scrollLeft() + $window.width() - this.$control.width() - this.controlattrs.offsetx
        var controly=$window.scrollTop() + $window.height() - this.$control.height() - this.controlattrs.offsety
        this.$control.css({left:controlx+'px', top:controly+'px'})
    },

    togglecontrol:function(){
        var scrolltop=jQuery(window).scrollTop()
        if (!this.cssfixedsupport)
            this.keepfixed()
        this.state.shouldvisible=(scrolltop>=this.setting.startline)? true : false
        if (this.state.shouldvisible && !this.state.isvisible){
            this.$control.stop().animate({opacity:1}, this.setting.fadeduration[0])
            this.state.isvisible=true
        }
        else if (this.state.shouldvisible==false && this.state.isvisible){
            this.$control.stop().animate({opacity:0}, this.setting.fadeduration[1])
            this.state.isvisible=false
        }
    },
    
    init:function(){
        jQuery(document).ready(function($){
            var mainobj=scrolltotop
            var iebrws=document.all
            mainobj.cssfixedsupport=!iebrws || iebrws && document.compatMode=="CSS1Compat" && window.XMLHttpRequest //not IE or IE7+ browsers in standards mode
            mainobj.$body=(window.opera)? (document.compatMode=="CSS1Compat"? $('html') : $('body')) : $('html,body')
            mainobj.$control=$('<div id="topcontrol">'+mainobj.controlHTML+'</div>')
                .css({position:mainobj.cssfixedsupport? 'fixed' : 'absolute', bottom:mainobj.controlattrs.offsety, right:mainobj.controlattrs.offsetx, opacity:0, cursor:'pointer'})
                .attr({title:'Scroll Back to Top'})
                .click(function(){mainobj.scrollup(); return false})
                .appendTo('body')
            if (document.all && !window.XMLHttpRequest && mainobj.$control.text()!='') //loose check for IE6 and below, plus whether control contains any text
                mainobj.$control.css({width:mainobj.$control.width()}) //IE6- seems to require an explicit width on a DIV containing text
            mainobj.togglecontrol()
            $('a[href="' + mainobj.anchorkeyword +'"]').click(function(){
                mainobj.scrollup()
                return false
            })
            $(window).bind('scroll resize', function(e){
                mainobj.togglecontrol()
            })
        })
    }
}

scrolltotop.init()

3. 

<div id="container">
</div>

.go-top{ width:25px; height:65px; position:absolute; right:-30px;}
.go-top a{ display:block; cursor:pointer; outline:none;}

$(function(){
    var topDistance = 450;//go-top距顶端距离
    var showDistance = 1;//距离顶端多少距离开始显示go-top
    var gotopCon = "<div class='go-top'><a href='#'><img src='images/gotop.gif' /></a></div>"
    var thisTop = $(window).scrollTop() + topDistance;
    $("#container").css("position","relative");
    $("#container").append(gotopCon);
    $(".go-top").css("top",thisTop);
    if($(window).scrollTop() < showDistance){
        $(".go-top").hide();
        }
    $(window).scroll(function(){
        thisTop = $(this).scrollTop() + topDistance;
        $(".go-top").css("top",thisTop);
        if($(this).scrollTop() < showDistance){
            $(".go-top").fadeOut("fast");
            }else{
                $(".go-top").fadeIn("fast");
                }
        });
    $("a",".go-top").click(function(){
        $("html").animate({scrollTop:0},"fast");//IE,FF
        $("body").animate({scrollTop:0},"fast");//Webkit
        return false;
        });
    });

 

<script type="text/javascript">
/**
 * 回到页面顶部
 * @param acceleration 加速度
 * @param time 时间间隔 (毫秒)
 **/
function goTop(acceleration, time) {
    acceleration = acceleration || 0.1;
    time = time || 16;
 
    var x1 = 0;
    var y1 = 0;
    var x2 = 0;
    var y2 = 0;
    var x3 = 0;
    var y3 = 0;
 
    if (document.documentElement) {
        x1 = document.documentElement.scrollLeft || 0;
        y1 = document.documentElement.scrollTop || 0;
    }
    if (document.body) {
        x2 = document.body.scrollLeft || 0;
        y2 = document.body.scrollTop || 0;
    }
    var x3 = window.scrollX || 0;
    var y3 = window.scrollY || 0;
 
    // 滚动条到页面顶部的水平距离
    var x = Math.max(x1, Math.max(x2, x3));
    // 滚动条到页面顶部的垂直距离
    var y = Math.max(y1, Math.max(y2, y3));
 
    // 滚动距离 = 目前距离 / 速度, 因为距离原来越小, 速度是大于 1 的数, 所以滚动距离会越来越小
    var speed = 1 + acceleration;
    window.scrollTo(Math.floor(x / speed), Math.floor(y / speed));
 
    // 如果距离不为零, 继续调用迭代本函数
    if(x > 0 || y > 0) {
        var invokeFunction = "goTop(" + acceleration + ", " + time + ")";
        window.setTimeout(invokeFunction, time);
    }
} 
</script>