Woo Commerce Dropdown to filter product tag within an archive page.

woo_dropdown_product_tag_filter.php

<?php

function displayLocationDropdown() {

  $html = '';
	$html .= '<form class="location-select" method="post">';
	$html .= '<select id="location-selector" name="location" class="location">';
	
	$tag = wp_tag_cloud( array(
		'format' => 'array',
		'taxonomy' => 'product_tag' 
	) );
	$page_path = $_SERVER["REQUEST_URI"];
	$page_url = site_url() . $page_path;
	$url_parts = parse_url($page_url);
	$constructed_url = $url_parts['scheme'] . '://' . $url_parts['host'] . (isset($url_parts['path'])?$url_parts['path']:'');
	
	$html .= '<option value="#">--Select Location--</option>';
	
	foreach($tag as $tagkey => $tagvalue)
	{
		$cleanedup = strip_tags($tagvalue);
		$tag_info = get_term_by('name', $cleanedup, 'product_tag', 'ARRAY_A');
		$tag_slug = $tag_info['slug'];
		if(isset($_GET['product_tag'])) {
			$value_url = $constructed_url . '?product_tag=' . $tag_slug;
		} else {
			$value_url = $page_url . '?product_tag=' . $tag_slug;
		}
		$html .= '<option value="' . $value_url . '">' . $cleanedup . '</option>';
	}
	$html .= '<option value="' . $constructed_url . '">View All Locations</option>'; ///site_url() instead $constructed_url is probably better
	
	$html .= '</select>';
	$html .= '</form>';
	
	echo $html;
}

add_action('woocommerce_before_shop_loop', 'displayLocationDropdown', 40);

add_action('wp_head', 'addDisplayLocationScript');
function addDisplayLocationScript() {
	$script = '';
	$script .= '<script type="text/javascript">';
    $script .= 'jQuery(document).ready(function() {';
    $script .= '    jQuery("#location-selector").change(function() {';
    $script .= '        location = jQuery("#location-selector option:selected").val();';
    $script .= '    });';
    $script .= '});';
    $script .= '</script>';
    
    echo $script;
}