Jquery - Table Sort

HTML

<table id="sort-table">
    <thead >
         <tr>
            <th class="sort-table asc"><p>Column</p></th>
        </tr>
    </thead>
    <tbody>
        <tr><td>he</td></tr>
        <tr><td>stackoverflow</td></tr>
        <tr><td>by</td></tr>
        <tr><td>vote</td></tr>
        <tr><td>post</td></tr>
        <tr><td>And</td></tr>
        <tr><td>clicking</td></tr>
        <tr><td>up</td></tr>
        <tr><td>did</td></tr>
    </tbody>
</table>
<br>

JavaScript

var flag = false;

$('.sort-table').click(function (e) {

        var $sort = this;
        var $table = $('#sort-table');
        var $rows = $('tbody > tr', $table);
        if (flag == false) {
            $rows.sort(function (a, b) {
                var keyA = $('td', a).text();
                var keyB = $('td', b).text();
                
                $($sort).addClass('asc');
                return (keyA > keyB) ? 1 : 0;
               
            });
            flag = true;
        }
        else {
            $rows.sort(function (a, b) {
                var keyA = $('td', a).text();
                var keyB = $('td', b).text();

                $($sort).addClass('desc');
                return (keyA < keyB) ? 1 : 0;
            });
            flag = false;
        }
        $.each($rows, function (index, row) {
            $table.append(row);
        });
        e.preventDefault();
    });