例:
<ul class="nav_c_ul">
<a class="nav_c_ul_a focus" href="javascript:void(0)" οnclick="location.href='/infopublish/column/2';return false;">
<li class="nav_c_li"></li>
</a>
<a class="nav_c_ul_a" href="javascript:void(0)" οnclick="location.href='/infopublish/column/4';return false;">
<li class="nav_c_li"></li>
</a>
<a class="nav_c_ul_a" href="javascript:void(0)" οnclick="location.href='/infopublish/column/12';return false;">
<li class="nav_c_li"></li>
</a>
</ul>
焦点判断:
if($('a.focus').is('.nav_c_ul>a:nth-of-type(2) ')){alert(1)} //ul 标签下的第二个a标签聚焦 弹出框弹出 1;
if($('a.focus').is('.nav_c_ul>a:first-of-type')){alert(1)} //ul 标签下的第一个a标签聚焦 弹出框弹出 1;
if($('a.focus').is('.nav_c_ul>a:last-of-type')){alert(1)} //ul 标签下的最后一个a标签聚焦 弹出框弹出 1;