add support for google tag manager

_config.yml

@@ -69,8 +69,10 @@ netease_comment: false
 # ba_track_id: [your track id]
 
 # Google Tag Manager
-gtm_id: "G-077BT1Q7PJ"
+# gtm_id: "GTM-MCXT2HK5"
+
 # Google Analytics
+gtag_id: "G-077BT1Q7PJ"
 ga_track_id: "" # Format: UA-xxxxxx-xx
 ga_domain: 
 

_includes/footer.html

@@ -130,14 +130,24 @@
 </script>
 
 {% if site.gtm_id %}
+<!-- Google Tag Manager -->
+<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
+new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
+j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
+'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
+})(window,document,'script','dataLayer','{{ site.gtm_id }}');</script>
+<!-- End Google Tag Manager -->
+{% endif %}
+
+{% if site.gtag_id %}
 <!-- Google tag (gtag.js) -->
-<script async src="https://www.googletagmanager.com/gtag/js?id={{ site.gtm_id }}"></script>
+<script async src="https://www.googletagmanager.com/gtag/js?id={{ site.gtag_id }}"></script>
 <script>
   window.dataLayer = window.dataLayer || [];
   function gtag(){dataLayer.push(arguments);}
   gtag('js', new Date());
 
-  gtag('config', '{{ site.gtm_id }}');
+  gtag('config', '{{ site.gtag_id }}');
 </script>
 {% endif %}