Add a dropdown filter for wordpress taxonomies

functions.php

function get_terms_dropdown_type($taxonomy, $args)
{
	$taxo_obj = get_taxonomy($taxonomy);
	$taxo_singular_name = $taxo_obj->labels->singular_name;
	$terms_obj = get_terms($taxonomy, $args);
	if ('category' === $taxonomy) {
		$taxonomy_name = 'cat';
	} elseif ('post_tag' === $taxonomy) {
		$taxonomy_name = 'tag';
	} else {
		$taxonomy_name = $taxonomy;
	}

	$output = "<select name='" . $taxonomy_name . "'>"; //CHANGE ME!
	$output .= "<option value=''>Select " . $taxo_singular_name . "</option>"; //CHANGE ME TO YOUR LIKING!
	foreach ($terms_obj as $term) {
		// $root_url = get_bloginfo('url');
		// $term_taxonomy = $term->taxonomy;
		$term_slug = $term->slug;
		$term_name = $term->name;
		$link = $term->term_id;
		$output .= "<option value='" . $term_slug . "'>" . $term_name . "</option>";
	}
	$output .= "</select>";
	return $output;
}

page.php

<form action="<?php bloginfo('url'); ?>" method="get">
    <div>
      <?php
      $taxonomies = array('TAXO_NAME#1', 'TAXO_NAME#2', 'TAXO_NAME#3'); //CHANGE ME!
      $args = array('orderby' => 'name', 'hide_empty' => true);

      foreach ($taxonomies as $taxonomy) {
        $select = get_terms_dropdown_type($taxonomy, $args);

        $select = preg_replace("#<select([^>]*)>#", "<select$1 onchange='return this.form.submit()'>", $select);
        echo $select;
      }

      ?>
      <input type="submit" name="submit" value="filter" />
    </div>
  </form>