How to know the 'sort status' of a bootstrap column

Question

<div class="table-responsive">

<table class="table table-condensed table-hover footable p-xs">

<thead>

<tr>

<th data-sort-ignore="true"></th>

<th id='abra' ng-click="vm.alteraOrdenacao('Id')">Id</th>

<th ng-click="vm.alteraOrdenacao('Fila')">Fila</th>

<th ng-click="vm.alteraOrdenacao('Referência')">Referência</th>

 

I have one table like this one. When the user click a column, it automatically sort the items of the table. I captured the click of column but I want to know if the sort status of the clicked column is ascending or descending.