在侧边栏增加返回顶部按钮

<!--以下为返回顶部按钮代码-->
    <script type="text/javascript">
    var w = 50;
    var h = 59;
    var str = "";
    var obj = document.getElementById("divStayTopLeft");
    if (obj)str = obj.innerHTML;
    if( typeof document.compatMode != 'undefined' && document.compatMode != 'BackCompat'){
    document.writeln('<DIV  style="z-index:9;right:0;bottom:0;height:'+h+'px;width:'+w+'px;overflow:hidden;POSITION:fixed;_position:absolute; _margin-top:expression(document.documentElement.clientHeight-this.style.pixelHeight+document.documentElement.scrollTop);">');
    }
    else {
    document.writeln('<DIV  style="z-index:9;right:0;bottom:0;height:'+h+'px;width:'+w+'px;overflow:hidden;POSITION:fixed;*position:absolute; *top:expression(eval(document.body.scrollTop)+eval(document.body.clientHeight)-this.style.pixelHeight);">');
    }
    document.writeln('<div style="clear:both;margin:auto;height:59px;font-size:16px;overflow:hidden;font-weight:bold;text-align:left;"><a href="javascript:scroll(0,0)" hidefocus="true"><img src="http://ihb65.com/content/templates/DaZengCMS/images/totop.png" alt="回到顶部" style="border: 0px;" /></a></div> ');
    document.write('<div style="clear:both;margin:auto;overflow:hidden;text-align:left;">'+str+'</div>');
    document.writeln('</DIV>');
    </script>