On form change send to url with jQuery

HTML

<div id="myID">108</div>
<form class="aclass" target="_blank" method="post">
    <select id="select">
        <option value="1">aaa</option>
        <option value="2">bbb</option>
    </select>
</form>

JavaScript

var pageurl = window.location.protocol + "//" + window.location.host + window.location.pathname;
var myID = jQuery('#myID').html() || '';
var myURL = '?a=' + myID + '&tg=';
jQuery('.aclass select').change(function () {
    var opVal = jQuery(this).val() || 0;
    var finalURL = pageurl + myURL + opVal;
    alert(finalURL);
    jQuery(this).closest(".aclass").attr("action", finalURL);
    alert(jQuery(this).closest(".aclass").attr('action'));
    this.form.submit();
});