feat($plugin-google-analytics): ga4(fix #2713)

packages/@vuepress/plugin-google-analytics/enhanceAppFileV4.js

@@ -0,0 +1,23 @@
+// Patch for Google Analytics 4
+
+/* global GM_ID */
+export default (_ctx) => {
+  // Google analytics integration
+  if (process.env.NODE_ENV === 'production' && GM_ID && typeof window !== 'undefined') {
+    (function (global, doc, tag, src, script, m) {
+      script = doc.createElement(tag)
+      m = doc.getElementsByTagName(tag)[0]
+      script.async = 1
+      script.src = src
+      m.parentNode.insertBefore(script, m)
+      global.dataLayer = global.dataLayer || []
+      if (!global.gtag) {
+        global.gtag = function gtag () {
+          global.dataLayer.push(arguments)
+        }
+        global.gtag('js', new Date())
+        global.gtag('config', GM_ID)
+      }
+    })(window, document, 'script', `https://www.googletagmanager.com/gtag/js?id=${GM_ID}`)
+  }
+}

packages/@vuepress/plugin-google-analytics/index.js

@@ -7,9 +7,15 @@ module.exports = (options = {}, context) => ({
   define () {
     const { siteConfig = {}} = context
     const ga = options.ga || siteConfig.ga
+    const gm = options.gm || siteConfig.gm
     const GA_ID = ga || false
-    return { GA_ID }
+    // GM_ID is the Google Analytics ID for GA4
+    const GM_ID = gm || false
+    return { GA_ID, GM_ID }
   },
 
-  enhanceAppFiles: path.resolve(__dirname, 'enhanceAppFile.js')
+  enhanceAppFiles: [
+    path.resolve(__dirname, 'enhanceAppFile.js'),
+    path.resolve(__dirname, 'enhanceAppFileV4.js')
+  ]
 })