ENH: Support Google Analytics 4 tracking

Author: kernc

pdoc/templates/config.mako

@@ -38,8 +38,8 @@
     #     Demo: https://highlightjs.org/static/demo/
     hljs_style = 'github'
 
-    # If set, insert Google Analytics tracking code. Value is GA
-    # tracking id (UA-XXXXXX-Y).
+    # If set, insert Google Analytics 4 tracking code. Value is GA
+    # tracking id (G-XXXXXXXXXX).
     google_analytics = ''
 
     # If set, insert Google Custom Search search bar widget above the sidebar index.

pdoc/templates/html.mako

@@ -392,10 +392,13 @@
   <style media="print">${css.print()}</style>
 
   % if google_analytics:
+    <script async src="https://www.googletagmanager.com/gtag/js?id=${google_analytics}"></script>
     <script>
-    window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;
-    ga('create', '${google_analytics}', 'auto'); ga('send', 'pageview');
-    </script><script async src='https://www.google-analytics.com/analytics.js'></script>
+      window.dataLayer = window.dataLayer || [];
+      function gtag(){dataLayer.push(arguments);}
+      gtag('js', new Date());
+      gtag('config', '${google_analytics}');
+    </script>
   % endif
 
   % if google_search_query:

pdoc/test/__init__.py

@@ -433,10 +433,10 @@ def test_output_text(self):
                                              for file in self.PUBLIC_FILES])
 
     def test_google_analytics(self):
-        expected = ['google-analytics.com']
+        expected = ['googletagmanager.com']
         with run_html(EXAMPLE_MODULE):
             self._check_files((), exclude_patterns=expected)
-        with run_html(EXAMPLE_MODULE, config='google_analytics="UA-xxxxxx-y"'):
+        with run_html(EXAMPLE_MODULE, config='google_analytics="G-xxxxxxxxxx"'):
             self._check_files(expected)
 
     def test_relative_dir_path(self):