How to trigger javascript event using select box

<script>
            function fireonId(thisVal) {
                var value = incontrol.options[incontrol.selectedIndex].value;
                        if (value == 'confirm') {
                    document.getElementById('fireonId').style.visibility = 'visible';
                } else {
                    document.getElementById('fireonId').style.visibility = 'hidden';
                }
            }
        </script>
        <select class="select3" name="fireonIdType" onchange="fireonId(this)">
            <option selected="selected" value="select">- Select fireon.in Type -</option>
            <option value="suspect">Suspected</option>
            <option value="confirm">Confirmed</option>
        </select>

        <select class="select4" id="test" name="fireonId" style="visibility: hidden;">
            <option selected="selected">- Select fireon.in -</option>
        </select>