Working drop down in search for CPT
<?php
$categories = get_categories('taxonomy=custom-tax');
$select = "<select name="cat" id='cat' class="postform">n";
$select.= "<option value="-1">Select category</option>n";
foreach($categories as $category){
if($category->count > 0){
$select.= "<option value="".$category->slug."">".$category->name."</option>";
}
}
$select.= "</select>";
echo $select;
?>
<script type="text/javascript"><!--
var dropdown = document.getElementById("cat");
function onCatChange() {
if ( dropdown.options[dropdown.selectedIndex].value != -1 ) {
location.href = "https://wordpress.stackexchange.com/questions/315973/<?php echo home_url();?>/category/"+dropdown.options[dropdown.selectedIndex].value+"https://wordpress.stackexchange.com/";
}
}
dropdown.onchange = onCatChange;
--></script>