Add support for Google Analitics global site tag

libs/plugins/google-analytics/src/lib/plugins-google-analytics.ts

@@ -1,4 +1,4 @@
-import { registerPlugin, getMyConfig } from '@scullyio/scully';
+import { getMyConfig, registerPlugin } from '@scullyio/scully';
 
 export const GoogleAnalytics = 'googleAnalytics';
 
@@ -8,22 +8,39 @@ export const googleAnalyticsPlugin = async (html: string): Promise<string> => {
   if (!googleAnalyticsConfig) {
     throw new Error('googleAnalytics plugin missing Global Site Tag');
   }
-  const siteTag: string = googleAnalyticsConfig['globalSiteTag'];
 
-  const googleAnalyticsScript = `
+  const googleAnalyticsScript = getSnippet(googleAnalyticsConfig['globalSiteTag']);
+
+  return html.replace(/<\/head/i, `${googleAnalyticsScript}</head`);
+};
+
+const validator = async () => [];
+
+registerPlugin('postProcessByHtml', GoogleAnalytics, googleAnalyticsPlugin, validator);
+
+function getSnippet(siteTag: string) {
+  if (siteTag.startsWith('G-')) {
+    return `
+<!-- Global site tag (gtag.js) - Google Analytics -->
+<script async src="https://www.googletagmanager.com/gtag/js?id=${siteTag}"></script>
+<script>
+  window.dataLayer = window.dataLayer || [];
+  function gtag(){dataLayer.push(arguments);}
+  gtag('js', new Date());
+
+  gtag('config', '${siteTag}');
+</script>
+`;
+  }
+
+  return `
 <!-- Google Analytics -->
   <script sk>
   window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;
   ga('create', '${siteTag}', 'auto');
   ga('send', 'pageview');
   </script>
   <script sk async src='https://www.google-analytics.com/analytics.js'></script>
-  <!-- End Google Analytics -->
+<!-- End Google Analytics -->
 `;
-
-  return html.replace(/<\/head/i, `${googleAnalyticsScript}</head`);
-};
-
-const validator = async () => [];
-
-registerPlugin('postProcessByHtml', GoogleAnalytics, googleAnalyticsPlugin, validator);
+}