Table sorter icons in thead - css

Question

I have some JavaScript that toggles the class of the th element clicked to "ascending" or "descending".
Q: In the css, how can I display a jQuery-UI icon associated with .ascending or .descending?
<table>
<thead>
<tr>
<th class="ascending">Cust</th>
<th>Name</th>
</tr>
</thead>
...
</table>
Here's the code, just in case someone spots an inefficiency:
jQuery(function($) {
$('.thSort th').click(function() {
var $th = $(this);
$th.siblings().removeClass('selected ascending descending');
$th.addClass('selected');
var column = $th.index();
var $table = $th.closest('table');
var rows = $table.find('tbody > tr').get();
if ($th.hasClass('ascending')) {
$th.removeClass('ascending');
$th.addClass('descending');
rows.sort(function(rowA,rowB) {
var keyA = $(rowA).children('td').eq(column).text().toUpperCase();
var keyB = $(rowB).children('td').eq(column).text().toUpperCase();
if (keyA < keyB) return 1;
if (keyA > keyB) return -1;
return 0;
});
} else {
$th.removeClass('descending');
$th.addClass('ascending');
rows.sort(function(rowA,rowB) {
var keyA = $(rowA).children('td').eq(column).text().toUpperCase();
var keyB = $(rowB).children('td').eq(column).text().toUpperCase();
if (keyA < keyB) return -1;
if (keyA > keyB) return 1;
return 0;
});
}
$.each(rows, function(index,row) {
$table.children('tbody').append(row);
});
return false;
});
});

Answer 1

taking this from the jquery Tablesorter plugin
you can write some css like this:
table thead th{
background-repeat: no-repeat;
background-position: center right;
cursor: pointer;
}
.ascending{
background-image: url(asc.gif);
}
.decending{
background-image: url(desc.gif);
}

Answer 2

<th scope="col"><div class="floatleft">Topic</div>
<div class="floatright ui-state-default ui-corner-all">
<span class="ui-icon ui-icon-circle-triangle-n"></span>
</div>
</th>
In JavaScript, toggle between ui-icon-circle-triangle-n and ui-icon-circle-triangle-s.
If the user clicks on a new th, replace all the html inside the previous th with only the text that is in the first div.