Update extra.js

docs/javascripts/extra.js

@@ -1,9 +1,16 @@
-app.location$.subscribe(function (url) {
+var gtag_id = "G-ZZKM4MPQXL";
+
+var script = document.createElement("script");
+script.src = "https://www.googletagmanager.com/gtag/js?id=" + gtag_id;
+document.head.appendChild(script);
+
+location$.subscribe(function (url) {
   window.dataLayer = window.dataLayer || [];
+
   function gtag() {
     dataLayer.push(arguments);
   }
-  gtag("js", new Date());
 
-  gtag("config", "G-ZZKM4MPQXL");
+  gtag("js", new Date());
+  gtag("config", gtag_id);
 });