jquery返回顶部-ie6配合css表达式。

css:

.wraper{ width:980px; height:2048px; margin:0 auto; background:#ccc; }

/*返回头部*/

#backToTop a{ display:block; cursor:pointer;width:25px; height:26px; text-indent:-9999em; position:absolute; left:0; top:0; z-index:10;}

#backToTop .bt_bg{

        background:url(http://i0.cy.com/xtl/main/20140227/backTop.png) no-repeat;_background: 0; _filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='http://i0.cy.com/xtl/main/20140227/backTop.png',sizingMethod='scale'); 

        width:25px; height:26px ; position:absolute; left:0; top:0; z-index:8; }

#backToTop { display:none; width:25px; height:26px ; position:fixed; right:50%; margin-right:-533px; bottom:110px; z-index:1; }

/**针对ie6设置*/

*html #backToTop { position:absolute; margin-top:expression(0 - parseInt(this.offsetHeight / 2) + (TBWindowMargin = document.documentElement && document.documentElement.scrollTop || document.body.scrollTop) + 'px');}

 

html:

    <div class="wraper">

        

    </div>

    <script type="text/javascript" src="http://www1.changyou.com/scripts/jquery.min.js"></script>

 

javascript：

    $('body').append($('<div id="backToTop"><a href="javascript:void(0);">回到顶部</a><div class="bt_bg"></div></div>').hide(0));

    $(window).scroll(function(){

        $('#backToTop').show();

        if ($(document).scrollTop() != 0) 

            $('#backToTop').show();

        else 

            $('#backToTop').hide();

    });

    $('#backToTop a').click(function(){

        $('html, body').animate({

            scrollTop: 0

        }, 800);

        return false;

    });