当有position:fixed;的时分锚定位时，锚定位时菜单不遮住

参考大神：http://blog.****.net/n1z1lam/article/details/24409223

<script type="text/javascript">
  //设置菜单悬浮（刚开始时菜单不在页面顶端）
	$(function(){
			$(window).scroll(function(){
         var scrollTop = $(document).scrollTop();
          if (scrollTop>441) {
           $(".single_newsBlock").css({"position":"fixed","top":"0px"});
          }else{
            $(".single_newsBlock").css({"position":"static"});
          };
      });
	})

  //锚定位
  function locateAt(e){ 
    var e =  document.getElementById(e);/*以id命名的锚点*/  
    var y = e.offsetTop;    
    var scrollTop = $(document).scrollTop();
    while(e=e.offsetParent){ y += e.offsetTop;} 
    if (scrollTop>441){
      y-=120;/*悬浮菜单的高度*/ 
    }else{
      y-=240;
    };
    window.scrollTo(0,y); 
  }
	</script>

 html:代码

<li><a href="javascript:void(0);" onclick="locateAt('topicNews')"><img src="../images/topicNews.png"></a></li>

 被定位的代码

<div class="moveApp" id="topicNews">
	<div class="moveApp_title ">
	</div>
	<div class="moveApp_content">
	</div>
</div><!-- moveApp -->