div展开或隐藏

<div class="ylnr_bt"><span>立案信息</span><a href="javascript:laxx()" title="展开或隐藏" class="a_lan3" style="float:right; margin-top:10px;"><i id="laxxtb" class="fa fa-angle-up"></i></a></div>

<table class="yl_biaoge laxx">
  <tr>
    <td colspan="4">代理人信息</td>
  </tr>
</table>

function laxx(){
  if($(".laxx").is(":hidden")){
    $(".laxx").show();
    $("#laxxtb").addClass("fa-angle-up").removeClass("fa-angle-down");
  }else{
    $(".laxx").hide();
    $("#laxxtb").addClass("fa-angle-down").removeClass("fa-angle-up");
  }
}