Buttons Plus & Minus

How to increment or decrement a form field using jQuery, specially useful for quantity fields.

HTML

<table class="vuln-table">

<tr role="row" class="even">
<td class="sorting_1"><input checked="true" type="checkbox" name="asfasdfd" id="vuln_checked_" value="asdfsdfa"></td>
<td>something</td>
<td><select class="form-control" name="test" id="kjhtkjehtehr"><option value="Severe">Severe</option>
<option value="High">High</option>
<option value="Medium">Medium</option>
<option selected="selected" value="Low">Low</option>
<option value="Informational">Informational</option>
</select>
</td>
<td></td>
</tr>


</table>

CSS

#myform {
  text-align: center;
  padding: 5px;
  border: 1px dotted #ccc;
  margin: 2%;
}

.qty {
  width: 40px;
  height: 25px;
  text-align: center;
}

input.qtyplus {
  width: 25px;
  height: 25px;
}

input.qtyminus {
  width: 25px;
  height: 25px;
}

JavaScript

function change_severity(severity) {
    $(".vuln-table tr").each(function() {
        $(this).find('td input:checked').each(function() {
            $(this).parent().parent().find("select").val(severity);
        });
    });
}

change_severity("Severe")