<script type="text/javascript">

//光标移动到顶部

this.to_top=function(){

     $("html,body").animate({scrollTop:0}, 500);

}

this.setCwinHeight=function (iframeObj) {

        /*     8、获取iframe的高度

         iframe.contentWindow.document.body.offsetHeight;

         如果要获取iframe中的iframe

         document.getElementById('iframId').onload=function(){

         var html= window.frames["name属性"].frames["name属性"].document.getElementById('iframe中的元素的id').innerHTML;  

         $('#iframeId').load(function() { //方法1

         var iframeHeight = Math.min(iframe.contentWindow.window.document.documentElement.scrollHeight, iframe.contentWindow.window.document.body.scrollHeight);

         var h=$(this).contents().height();

         $(this).height(h+'px');

         });

         */

        if (document.getElementById) {

            if (iframeObj && !window.opera) {

                if (iframeObj.contentDocument

                        && iframeObj.contentDocument.body.offsetHeight) {

                    if (a = iframeObj.getAttribute("id") == "video_top") {

                        iframeObj.height = iframeObj.contentWindow.document.body.offsetHeight;

                    } else if (iframeObj.getAttribute("id") == "video_bottom") {

                        iframeObj.height = iframeObj.contentWindow.document.body.offsetHeight;

                    } else if (document.frames[0].contentWindow

                            && document.frames[0].contentWindow.document.body.scrollHeight) {

                        var height = document.frames[0].document.body.scrollHeight;

                    }

                }

            }

        }

    }

</script>

//src为子frame间接路径

<iframe id="video_bottom" src="${pageContext.request.contextPath}/vcomment/videoBottom/${videoId}.htm" width="90%"  frameborder="0" scrolling="no" onload="setCwinHeight(this);"></iframe>