鼠标滚动div固定浮动-加锚点

页面：
<div class="pa">
<div class="w-95-sl bdl-2"><a>标题1</a></div>
<div class="w-95"><a data-index="_kfmessage">标题2</a></div>
<div class="w-95"><a data-index="_ctmessage">标题3</a></div>
<div class="w-95"><a data-index="_jtaddress">标题4</a></div>
<div class="w-95"><a data-index="_sjimage">标题5</a></div>
<div class="w-95"><a data-index="_cdintroduce">标题6</a></div>
<div class="w-95" style="width: 146px"><a data-index="_cdfacility">标题7</a></div>
<div class="clera">
</div>

浮动样式：
.fixedNav{ position:fixed; position:fixed ; left:50%; top:0px; z-index:1000; margin-left:-501px; margin-top:0px; }

浮动javascript:
<script type="text/javascript">
$(function myfunction() {
var offsetTop = $(".pa").offset().top;
$(window).scroll(function () {
var _top = $(document).scrollTop();
if (offsetTop < _top) {
$(".pa").addClass("fixedNav");
} else {
$(".pa").removeClass("fixedNav");
}
})
});
</script>
锚点滚动javascript:
<script type="text/javascript">
$(function () {
$(".pa a").click(function () {
//$(this).siblings().removeClass("current");
//$(this).addClass("current");
var el = $(this).attr('data-index');
$('html, body').animate({
scrollTop: $("#lab" + el).offset().top - 50
}, 500);
});
});
</script>