前台页面代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <link rel="stylesheet" type="text/css" href="index.css">
    <script type="text/javascript" src="jquery.min.js"></script>
    <script type="text/javascript" src="sucaijiayuan.js"></script>
</head>
<body>
    <div style="display: none;" id="rocket-to-top">
        <div style="opacity:0;display: block;" class="level-2"></div>
        <div class="level-3"></div>
    </div>
</body>
</html>

依赖jquery.js和sucaijiayuan.js，以及自定义css
index.css文件

*{list-style:none;border:0;}
body{height:800px;}
#rocket-to-top div {
    left: 0;
    margin: 0;
    overflow: hidden;
    padding: 0;
    position: absolute;
    top: 0;
    width: 149px;
}
#rocket-to-top .level-2 {
    background: url("rocket_button_up.png") no-repeat scroll -149px 0 transparent;
    display: none;
    height: 250px;
    opacity: 0;
    z-index: 1;
}
#rocket-to-top .level-3 {
    background: none repeat scroll 0 0 transparent;
    cursor: pointer;
    display: block;
    height: 150px;
    z-index: 2;
}
/*download by www.sucaijiayuan.com*/
#rocket-to-top {
    background: url("rocket_button_up.png") no-repeat scroll 0 0 transparent;
    cursor: default;
    display: block;
    height: 250px;
    margin: -125px 0 0;
    overflow: hidden;
    padding: 0;
    position: fixed;
    right: 0;
    top: 80%;
    width: 149px;
    z-index: 11;
}

sucaijiayuan.js文件

$(function() {
    var e = $("#rocket-to-top"),
    t = $(document).scrollTop(),
    n,
    r,
    i = !0;
    $(window).scroll(function() {
        var t = $(document).scrollTop();
        t == 0 ? e.css("background-position") == "0px 0px" ? e.fadeOut("slow") : i && (i = !1, $(".level-2").css("opacity", 1), e.delay(100).animate({
            marginTop: "-1000px"
        },
        "normal",
        function() {
            e.css({
                "margin-top": "-125px",
                display: "none"
            }),
            i = !0
        })) : e.fadeIn("slow")
    }),
    e.hover(function() {
        $(".level-2").stop(!0).animate({
            opacity: 1
        })
    },
    function() {
        $(".level-2").stop(!0).animate({
            opacity: 0
        })
    }),
    //download by www.sucaijiayuan.com
    $(".level-3").click(function() {
        function t() {
            var t = e.css("background-position");
            if (e.css("display") == "none" || i == 0) {
                clearInterval(n),
                e.css("background-position", "0px 0px");
                return
            }
            switch (t){
            case "0px 0px":
                e.css("background-position", "-298px 0px");
                break;
            case "-298px 0px":
                e.css("background-position", "-447px 0px");
                break;
            case "-447px 0px":
                e.css("background-position", "-596px 0px");
                break;
            case "-596px 0px":
                e.css("background-position", "-745px 0px");
                break;
            case "-745px 0px":
                e.css("background-position", "-298px 0px");
            }
        }
        if (!i) return;
        n = setInterval(t, 50),
        $("html,body").animate({scrollTop: 0},"slow");
    });
});

图片文件
回到顶部火箭demo_回到顶部

效果图

回到顶部火箭demo_回到顶部_02