<tfoot>
<select>
<option value="222"></option>
<option value="2222">2222</option>
<option value="zaza">zaza</option>
</select>
</tfoot>
I tried that:
$('tfoot select').val('zaza');
$("tfoot select").val("zaza")
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<tfoot>
<select>
<option value="222"></option>
<option value="2222">2222</option>
<option value="zaza">zaza</option>
</select>
</tfoot>
Any idea ? Select = make it selected = trigger the change event