using jquery :selected selector with next / previous arrows

using jquery :selected selector with next / previous arrows

HTML

<select id="mycars">
        <option value="a">a</option>
        <option value="b">b</option>
        <option value="c">c</option>
        <option value="d">d</option>
        <option value="e">e</option>
        <option value="f">f</option>
    </select>
    <a id="prev">prev</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a id="next">next</a>

JavaScript

$(document).ready(function () {
            $('#next').live('click', function () {
                var objMyCars = $('#mycars');
                if (objMyCars.find('option:last').prop('selected') === true) {
                    objMyCars.find('option:first').attr('selected', true);
                } else {
                    objMyCars.find('option:selected').next().attr('selected', true);
                }
            });

            $('#prev').live('click', function () {
                var objMyCars = $('#mycars');
                if (objMyCars.find('option:first').prop('selected') === true) {
                    objMyCars.find('option:last').attr('selected', true);
                } else {
                    objMyCars.find('option:selected').prev().attr('selected', true);
                }
            });
        });