javascript - 求助!!! Html Css Footer的设置

<code class="javascript">footer: function() {
        var footerHeight = 0,
            footerTop = 0,
            $footer = $(".footer");
        positionFooter();
        //定义positionFooter function
        function positionFooter() {
            //取到div#footer高度
            footerHeight = $footer.height();
            //div#footer离屏幕顶部的距离
            footerTop = ($(window).scrollTop() + $(window).height() - footerHeight) + "px";
            /* DEBUGGING STUFF
                console.log("Document height: ", $(document.body).height());
                console.log("Window height: ", $(window).height());
                console.log("Window scroll: ", $(window).scrollTop());
                console.log("Footer height: ", footerHeight);
                console.log("Footer top: ", footerTop);
                console.log("-----------")
            */
            //如果页面内容高度小于屏幕高度，div#footer将绝对定位到屏幕底部，否则div#footer保留它的正常静态定位
            if (($(document.body).height() + footerHeight) </code>