scrpit执行同页面内容切换

<div onclick="pageClick(this)" id="news" class="active"><img src="img/icon-1.png" />个人消息</div>

<iframe src="all_Student.jsp" height="713px" id="a1"
        name="ifd" onload="this.height=ifd.document.body.scrollHeight" 
        width="100%" scrolling="no" frameborder="1" ></iframe>

<script type="text/javascript">
    var news=document.getElementById('news');
    news.onclick=function(){
        a1.style.display="none";
    }
</script>