返回顶部功能

项目网页中需要使用“返回顶部”的功能，在网上找了代码，链接如下：

http://www.zhangxinxu.com/study/201104/back-to-top-jquery.html 

只需要css及js代码即可，浏览器兼容

 .backToTop {

    display: none;
    width: 18px;
    line-height: 1.2;
    padding: 5px 0;
    background-color: #000;
    color: #fff;
    font-size: 12px;
    text-align: center;
    position: fixed;
    _position: absolute;
    right: 10px;
    bottom: 100px;
    _bottom: "auto";
    cursor: pointer;
    opacity: .6;
    filter: Alpha(opacity=60);
}

 js代码：

 (function() {

    var $backToTopTxt = "返回顶部", $backToTopEle = $('<div class="backToTop"></div>').appendTo($("body"))
        .text($backToTopTxt).attr("title", $backToTopTxt).click(function() {
            $("html, body").animate({ scrollTop: 0 }, 120);
    }), $backToTopFun = function() {
        var st = $(document).scrollTop(), winh = $(window).height();
        (st > 0)? $backToTopEle.show(): $backToTopEle.hide();    
        //IE6下的定位
        if (!window.XMLHttpRequest) {
            $backToTopEle.css("top", st + winh - 166);    
        }
    };
    $(window).bind("scroll", $backToTopFun);
    $(function() { $backToTopFun(); });
})();