i’m really sorry.. this is the real code.. please anybody help me..
<?php print wpbusdirman_post_list_categories(); ?>
<script type="text/javascript">
var dropdown = document.getElementById("cat");
function onCatChange() {
if ( dropdown.options[dropdown.selectedIndex].value > 0 ) {
location.href = "<?php get_category_link('cat="+dropdown.options[dropdown.selectedIndex].value+" ') ?>";
}
}
dropdown.onchange = onCatChange;
</script>