jquery: use checksum of css files for versioning

Fixes gh-469

Author: timmywil

themes/jquery/functions.jquery.php

@@ -183,3 +183,14 @@ function jq_search_get_provider() {
 	}
 	return '';
 }
+
+/**
+ * Get a checksum of styles used in the header
+ */
+function jq_css_checksum() {
+	$base = get_template_directory() . '/css/base.css';
+	$typesense = get_template_directory() . '/lib/typesense-minibar/typesense-minibar.css';
+	$styles = get_stylesheet_directory() . '/style.css';
+
+	return md5( filemtime( $base ) . filemtime( $typesense ) . filemtime( $styles ) );
+}

themes/jquery/header.php

@@ -17,16 +17,16 @@
 	<meta name="viewport" content="width=device-width">
 
 	<link rel="shortcut icon" href="<?php echo get_stylesheet_directory_uri(); ?>/i/favicon.ico">
-	<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/lib/typesense-minibar/typesense-minibar.css?v=1.3.4">
-	<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/css/base.css?v=17">
-	<link rel="stylesheet" href="<?php bloginfo( 'stylesheet_url' ); ?>?v=8">
+	<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/lib/typesense-minibar/typesense-minibar.css?v=<?php echo jq_css_checksum(); ?>">
+	<link rel="stylesheet" href="<?php echo get_template_directory_uri(); ?>/css/base.css?v=<?php echo jq_css_checksum(); ?>">
+	<link rel="stylesheet" href="<?php bloginfo( 'stylesheet_url' ); ?>?v=<?php echo jq_css_checksum(); ?>">
 
 	<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
 	<script src="<?php echo get_template_directory_uri(); ?>/js/main.js"></script>
 <?php
 	if ( jq_search_get_provider() === 'typesense' ) :
 ?>
-	<script defer type="module" src="<?php echo get_template_directory_uri(); ?>/lib/typesense-minibar/typesense-minibar.js?v=1.3.4"></script>
+	<script defer type="module" src="<?php echo get_template_directory_uri(); ?>/lib/typesense-minibar/typesense-minibar.js?v=<?php echo jq_css_checksum(); ?>"></script>
 <?php
 	endif;