add gtag

public/index.html

@@ -6,6 +6,16 @@
     <meta name="viewport" content="width=device-width,initial-scale=1.0">
     <link rel="icon" href="<%= BASE_URL %>favicon.ico">
     <title>CoreUI - Vue Open Source Bootstrap Admin Template</title>
+    <script async src="https://www.googletagmanager.com/gtag/js?id=UA-118965717-3"></script>
+    <script>
+      window.dataLayer = window.dataLayer || [];
+      function gtag(){dataLayer.push(arguments);}
+      gtag('js', new Date());
+      // Shared ID
+      gtag('config', 'UA-118965717-3');
+      // Vue.js ID
+      gtag('config', 'UA-118965717-7');
+    </script>
   </head>
 
   <!-- BODY options, add following classes to body to change options