Update from analytics.js to gtag.js (#1559)

Co-authored-by: Ian Butterworth <[email protected]>
Co-authored-by: Morten Piibeleht <[email protected]>

CHANGELOG.md

@@ -12,6 +12,8 @@
 
 * ![Enhancement][badge-enhancement] The generated HTML sites can now detect if the version the user is browsing is not for the latest version of the package and display a notice box to the user with a link to the latest version. In addition, the pages get a `noindex` tag which should aid in removing outdated versions from search engine results. ([#1302][github-1302], [#1449][github-1449], [#1577][github-1577])
 
+* ![Enhancement][badge-enhancement] The analytics in the HTML output now use the `gtag.js` script, replacing the old deprecated setup. ([#1559][github-1559])
+
 * ![Bugfix][badge-bugfix] A bad `repo` argument to `deploydocs` containing a protocol now throws an error instead of being misinterpreted. ([#1531][github-1531], [#1533][github-1533])
 
 * ![Bugfix][badge-bugfix] SVG images generated by `@example` blocks are now properly scaled to page width by URI-encoding the images, instead of directly embedding the SVG tags into the HTML. ([#1537][github-1537], [#1538][github-1538])
@@ -788,6 +790,7 @@
 [github-1553]: https://github.com/JuliaDocs/Documenter.jl/pull/1553
 [github-1556]: https://github.com/JuliaDocs/Documenter.jl/issues/1556
 [github-1557]: https://github.com/JuliaDocs/Documenter.jl/pull/1557
+[github-1559]: https://github.com/JuliaDocs/Documenter.jl/pull/1559
 [github-1567]: https://github.com/JuliaDocs/Documenter.jl/pull/1567
 [github-1577]: https://github.com/JuliaDocs/Documenter.jl/pull/1577
 

src/Writers/HTMLWriter.jl

@@ -899,18 +899,18 @@ function asset_links(src::AbstractString, assets::Vector{HTMLAsset})
     return links
 end
 
-analytics_script(tracking_id::AbstractString) =
-    isempty(tracking_id) ? Tag(Symbol("#RAW#"))("") : Tag(:script)(
-        """
-        (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
-        (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
-        m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
-        })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
-
-        ga('create', '$(tracking_id)', 'auto');
-        ga('send', 'pageview', {'page': location.pathname + location.search + location.hash});
-        """
-    )
+function analytics_script(tracking_id::AbstractString)
+    @tags script
+    isempty(tracking_id) ? Tag(Symbol("#RAW#"))("") : [
+        script[:async, :src => "https://www.googletagmanager.com/gtag/js?id=$(tracking_id)"](),
+        script("""
+          window.dataLayer = window.dataLayer || [];
+          function gtag(){dataLayer.push(arguments);}
+          gtag('js', new Date());
+          gtag('config', '$(tracking_id)', {'page_path': location.pathname + location.search + location.hash});
+        """)
+    ]
+end
 
 function warning_script(src, ctx)
     if ctx.settings.warn_outdated